2 2021 38 MAGNETIC RESONANCE IMAGING IN THE ASSESSMENT OF FETAL CENTRAL NERVOUS SYSTEM ANOMALIES MRI SAFETY AND MANAGEMENT OF PATIENTS WITH CARDIOVASCULAR IMPLANTABLE ELECTRONIC DEVICES: LITERATURE REVIEW AND CASE PRESENTATION DIAGNOSTIC REFERENCE LEVELS IN DENTAL RADIOLOGY A SYSTEMATIC REVIEW ISSN 2712-2492 print ISSN 2712-2492 online ISSN 2738-4012 Medical Imaging and Radiotherapy Journal Publisher / Izdajatelj: Slovenian Society of Radiographers Društvo radioloških inženirjev Slovenije Editor-in-chief / Glavni urednik: Nejc Mekiš nejc.mekis@zf.uni-lj.si Editorial board / Uredniški odbor: Erna Alukić Sašo Arnuga Marjeta Jelovčan Gašper Podobnik Sebastijan Rep Tina Starc Adnan Šehić Rok Us Nika Zalokar Valerija Žager Marciuš Editorial offi ce / Naslov uredništva: Zdravstvena pot 5 1000 Ljubljana Slovenia Tel.: 01/300-11-51 Fax: 01/300-11-19 E-mail: nejc.mekis@zf.uni-lj.si Proofreader of Slovenian version / Lektorica slovenskega jezika: Tina Kočevar Proofreader of English version / Lektor angleškega jezika: Tina Kočevar The articles are reviewed by external review / Članki so recenzirani z zunanjo recenzijo Reviews are anonymous / Recenzije so anonimne Number of copies / Naklada: 100 copies / 100 izvodov Cover design / Oblikovanje naslovnice: Ana Marija Štimulak Graphic design and print / Grafi čno oblikovanje in tisk: Tisk 24 d.o.o., 1000 Ljubljana, Slovenia The journal is published twice a year / Revija izhaja dvakrat letno Indexed and abstracted by / Revijo indeksira: CINAHL (Cumulative Index to Nursing and Allied Health Literature), COBISS (COBIB union bibliographic/catalogue database) and dLib (Digital Library of Slovenia) The authors are responsible for all statements in their manuscripts. / Avtorji so odgovorni za vse navedbe v svojih člankih. This journal is printed on acid-free paper / Revija je natisnjena na brezkislinski papir This is an offi cial journal of the Slovenian Society of Radiographers with external reviews. The purpose is to publish articles from all areas of diagnostic imaging (diagnostic radiologic technology, CT, MR, US and nuclear medicine), therapeutic radiologic technology and oncology. The articles are professional and scientifi c: results of research, technological assessments, descriptions of cases, etc. Medical Imaging and Radiotherapy Journal (MIRTJ) 38 (2) 3 content 5 15 Edina SALKIĆ, Fuad JULARDŽIJA, Adnan ŠEHIĆ, Merim JUSUFBEGOVIĆ, Amela SOFIĆ, Meris JUŠIĆ, Jasmina BAJROVIĆ MAGNETIC RESONANCE IMAGING IN THE ASSESSMENT OF FETAL CENTRAL NERVOUS SYSTEM ANOMALIES Matic GODEC, Jani IZLAKAR, Gašper PODOBNIK MRI SAFETY AND MANAGEMENT OF PATIENTS WITH CARDIOVASCULAR IMPLANTABLE ELECTRONIC DEVICES: LITERATURE REVIEW AND CASE PRESENTATION 22 Alenka MATJAŠIČ DIAGNOSTIC REFERENCE LEVELS IN DENTAL RADIOLOGY: A SYSTEMATIC REVIEW 4 Medical Imaging and Radiotherapy Journal (MIRTJ) 38 (2) Dear colleagues, We are introducing the second issue of the Medical Imaging and Radiotherapy journal, volume 38 (2021). The journal’s editorial board is proud and happy that good word about our journal was spread and that we are receiving manuscripts from diff erent countries and diff erent topics. The journal remains a free open- access journal available to all readers on the journal’s website and in the databases that index the journal. We invite you to view the journal’s website, which is available at http://mirtjournal.net/index.php/home. All the necessary information of how to prepare and submit the manuscripts can be found on the mentioned website. Besides that, a complete archive of the journal from its very beginning. Nejc Mekis Editor-in-chief of MIRTJ Spoštovane kolegice in kolegi! Pred Vami je druga številka revije Medical imaging and Radiotherapy journal, letnik 38 (leto izdaje 2021). V uredništvu nam je v veliko veselje, da se je dobro ime o naši reviji razširilo in da redno pridobivamo članke iz različnih držav na različne tematike. Revija še vedno ostaja brezplačna in prosto dostopna vsem bralcem na spletni strani revije in v bazah, ki revijo indeksirajo. Vabimo vas, da si ogledate spletno stran revije, ki je dostopna na povezavi http://mirtjournal.net/index.php/home. Na omenjeni spletni strani najdete vse potrebne informacije za pripravo in oddajo člankov in prav tako celotno bazo vseh objavljenih člankov od začetka izdaje revije. Nejc Mekiš Glavni urednik MIRTJ Medical Imaging and Radiotherapy Journal (MIRTJ) 38 (2) 5 Review article MAGNETIC RESONANCE IMAGING IN THE ASSESSMENT OF FETAL CENTRAL NERVOUS SYSTEM ANOMALIES Edina SALKIĆ1, Fuad JULARDŽIJA2,3*, Adnan ŠEHIĆ2,3, Merim JUSUFBEGOVIĆ2,4, Amela SOFIĆ5, Meris JUŠIĆ6, Jasmina BAJROVIĆ2,4 1 MSc student, Faculty of Health Studies, University of Sarajevo, Sarajevo, Bosnia and Herzegovina 2 Department of radiology technologies, Faculty of Health Studies, University of Sarajevo, Sarajevo, Bosnia and Herzegovina 3 Insitute for health development, Faculty of Health Studies, University of Sarajevo, Sarajevo, Bosnia and Herzegovina 4 Radiology clinic, Clinical center of Sarajevo University, Sarajevo, Bosnia and Herzegovina 5 Radiology department, General hospital “Prim. dr Abdulah Hakaš”, Sarajevo, Bosnia and Herzegovina 6 PhD student, Faculty of Health Studies, University of Sarajevo, Sarajevo, Bosnia and Herzegovina * Corresponding author: Fuad Julardžija, Department of radiology technologies, Faculty of Health Studies, University of Sarajevo, Stjepana Tomića 1, 71000 Sarajevo, Bosnia and Herzegovina e-mail: fuad.julardzija@fzs.unsa.ba Received: 22. 11. 2021 Accepted: 11. 1. 2022 https://doi.org/10.47724/MIRTJ.2021.i02.a001 Medical Imaging and Radiotherapy Journal (MIRTJ) 38 (2) ABSTRACT Introduction: Fetal central nervous system (CNS) anomalies are among the most severe and common anomalies, with an incidence of 1: 100 to 1: 500 in newborns. Depending on the type of anomaly, the diagnosis can only be made at specifi c periods of pregnancy. The prenatal ultrasound (US) is an eff ective primary imaging modality for depicting these anomalies, and magnetic resonance imaging (MRI) is a method that provides useful confi rmation and resolves any doubts regarding the diagnosis made on prenatal ultrasound. In situations where ultrasound examination is diffi cult, fetal MRI can provide superior information owing to its many advantages. The aim of this study was to determine the importance of prenatal MRI in making an accurate diagnosis and assessment of fetal CNS anomalies after neurosonographic doubt and in detecting additional anomalies that might have been overlooked on ultrasound, which infl uences clinical decision making and anomaly outcomes. Material and methods: For this research, which was designed as a systematic review of the primary scientifi c research literature, numerous articles were used, i.e.17 scientifi c research papers, published in relevant scientifi c research online databases such as PubMed, Medline, Google Scholar, and the same were published in English in the period from 2015 to 2021. Results: From the assessment of the quality of studies with a cohort design, most studies used in this systematic review are high-quality studies (11 in total) and a smaller number are medium-quality studies (6 in total). Out of 575 cases, MRI confi rmed the ultrasound diagnosis and agreed with it in 59.8% of cases, while in 20.2% of cases, it changed the diagnosis, i.e., in 16.5%, it rejected the ultrasound diagnosis. Additional anomalies detected only on MRI occurred in 236/1225 cases, which totals 19.3% of additional anomalies. Termination of pregnancy was reported in 82/317 cases, accounting for 25.9%, while in 176 cases, the pregnancy continued. A total of 11 cases of neonatal death were reported, and the number of stillbirths or deaths after birth was reported in 8 cases. Conclusion: MRI using T2W SSFSE sequences in 3 planes, T1W and DWI in the axial plane, is a complementary modality to prenatal ultrasound in making an accurate diagnosis and assessment of CNS anomalies and detecting associated anomalies previously overlooked on ultrasound. Keywords: fetal magnetic resonance imaging, fetal neurosonography, fetal central nervous system anomalies, prenatal diagnosis. 6 Medical Imaging and Radiotherapy Journal (MIRTJ) 38 (2) Salkić E. et al./ Magnetic resonance imaging in the assessment of fetal central nervous system anomalies INTRODUCTION Magnetic Resonance Imaging (MRI) of the fetus or prenatal MRI is a non-invasive imaging method that shows the anatomical structures of the fetus without using ionizing radiation (1). Due to a higher contrast resolution than ultrasound, fetal MRI allows better diff erentiation of normal and abnormal tissue, thus providing detailed imaging data on fetal structures, especially the brain (2). MRI of the fetus is not recommended in the fi rst trimester of pregnancy unless the fetus is life- threatening. The use of intravenous contrast agents is not recommended to reduce the potentially harmful eff ects on the fetus (3). The key function of fetal MRI is early detection of congenital anomalies incompatible with life that require termination of pregnancy or the detection of those anomalies that will undergo surgery (1). Although fetal ultrasound (US) is the fi rst and basic screening method and an eff ective primary imaging modality for a depiction of central nervous system (CNS) abnormalities, MRI is a recognized complementary method for identifying fetal CNS pathology. It can provide additional and diagnostically important information, thus adding security to ultrasound diagnosis and assisting in parent counseling (4,5). The CNS anomalies are among themselves the most severe and common anomalies, with an incidence of 1: 100 to 1: 500 in newborns (6). Depending on the type of anomaly, the diagnosis can only be made at certain periods of pregnancy. Half of the anomalies are such that they lead either to the death of the fetus or signifi cantly disrupt life after birth, which is why timely detection and treatment are of great importance (7). In situations where ultrasound examination is diffi cult, fetal MRI can provide superior information, owing to its advantages such as superior contrast resolution, increased visual fi eld, the ability to shoot smoothly due to ossifi ed skull, increased amounts of adipose tissue on the front abdominal wall, oligohydramnios, fetal bones, a small amount of amniotic fl uid, the movements themselves, and an unfavorable position of the fetus are cases where MRI is a method of choice (8,9,10). In addition, a complete examination of the fetal CNS in the three spatial planes is obtained more consistently in the second and third trimesters by MRI than by ultrasound only (11). Prenatal fetal imaging has several challenges that require sequences that can minimize the eff ects of fetal movement and maternal breathing. The quality and resolution of the image should be such that they can adequately display essentially small anatomical details, and the diff erences in low tissue contrast should be made as large as possible to adequately defi ne the brain parenchyma (12). The development of a fast retrieval sequence from a single image with refocused echo (T2 weighted) has revolutionized fetal MRI because it has a layer acquisition time of less than a second and allows for eff ective “freezing” of fetal movements (13). Typically, the fetal CNS assessment protocol includes T2 weighted images following three planes of the fetal head, axial and coronal T1 weighted images, axial diff usion images (DWI), and/or diff usion tensor images (DTI); and additional sequences are performed as needed (9). The aim of this study was to determine the importance of prenatal MRI in making an accurate diagnosis and assessment of fetal CNS anomalies after neurosonographic suspicion and in detecting additional anomalies missed on ultrasound, which infl uences clinical decision-making and anomaly outcomes. MATERIAL AND METHODS Numerous articles were used for this research, designed as a systematic review of the primary scientifi c research literature. There were 17 scientifi c research papers published in relevant scientifi c research online databases such as PubMed, Medline, Google Scholar, and the same were published in English. Based on them, an analysis was conducted, and the basic characteristics of the study were selected (country, author, year of publication, title, type, study objectives, research method, results, and study conclusion). The studies used in this paper were published from 2015 to 2021. Based on them, we compared the results of the two modalities (ultrasound and magnetic resonance). We tried to determine the advantage of magnetic resonance imaging in the accurate assessment of CNS anomalies and the detection of associated anomalies and their impact on decisions about further pregnancy. The criterion for inclusion in the study included those studies that included pregnant women who were diagnosed or suspected of certain CNS abnormalities on prenatal ultrasound diagnosis of the fetus and who were then subjected to magnetic resonance imaging. At the same time, the exclusion criterion included the omission of any inclusion criterion, studies published in the period before 2015, then studies involving other abnormalities outside the CNS, and cases with contraindications for performing magnetic resonance imaging, such as claustrophobia, implanted pacemakers, prostheses, etc. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) fl ow diagram was used to document and report on all decisions made during the study selection process for this review paper, including the initial number of identifi ed studies, the number of excluded and included studies, and the reasons for their exclusion from the research (Diagram 1). The search keywords were: fetal magnetic resonance imaging, fetal neurosonography, central nervous system anomalies, prenatal diagnosis Medical Imaging and Radiotherapy Journal (MIRTJ) 38 (2) 7 Salkić E. et al./ Magnetic resonance imaging in the assessment of fetal central nervous system anomalies Total number of potential scientifi c research papers identifi ed by database search (n=291) Number of papers identifi ed after duplicate removal (n=261) Excluded papers (n = 145) Published before 2015 (n = 54) Other anatomical area outside CNS included (n = 18) Not in English (n = 13) Review papers / case reports, MERIDIAN studies / comments (n = 53) Pediatric population (n = 4) Not available for review (n = 3) Full text papers excluded (n=99): Abstract only / without full text (n = 25) No comparison of ultrasound and MRI / no data on ultrasound and / or MRI (n = 28) No data on CNS anomalies and / or additional CNS anomalies / present anomalies outside the CNS (n = 21) Not relevant (n = 25) Papers reviewed by title and abstract (n = 261) Full text papers considered suitable for research (n=116) Studies included in the systematic review (n=17) Id en tifi c at io n PRISMA model Sc re en in g In cl ud ed Diagram 1. PRISMA model RESULTS The quality assessment of the included cohort design studies (Table 1) was made according to the quality assessment tools developed by the National Heart, Lung and Blood Institute (NHLBI) in 2013 (14). Studies in which all or nearly all criteria are met and the weaknesses of the study cannot change, the study's fi ndings are qualifi ed as high-quality studies. Furthermore, medium- quality studies are considered to be those studies in which some of the criteria from the checklist are not met or if the criteria are not satisfactorily described. However, it is assumed that there is little chance that the weaknesses could have changed the study's fi ndings. In addition, there are inadequate/low- quality studies that include those studies that meet several or no criteria from the checklist and in such studies, weaknesses may mean that the conclusion of the study is wrong (14) 8 Medical Imaging and Radiotherapy Journal (MIRTJ) 38 (2) Salkić E. et al./ Magnetic resonance imaging in the assessment of fetal central nervous system anomalies Table 1. Quality assessment of included studies with a cohort design Main author, year, country, title 1 2 3 4 5 6 7 8 9 10 11 12 Total assessment quality The ENSO Working Group, 2020, Italy, Role of prenatal magnetic resonance imaging in fetuses with isolated mild or moderate ventriculomegaly in the era of neurosonography: an international multicenter study Y Y Y Y Y Y N Y Y Y N Y Medium quality Tanacan A. et al., 2020, Turkey, Prenatal diagnosis of central nervous system abnormalities: Neurosonography versus fetal magnetic resonance imaging Y Y Y Y Y Y U Y Y Y Y Y High quality Sefi dbakht S. et al., 2016, Iran, Fetal Central Nervous System Anomalies Detected by Magnetic Resonance Imaging: A Two- Year Experience Y Y Y Y N Y U Y Y Y Y Y Medium quality Mazor MM. et al., 2018, Israel, Added Value of Fetal MRI in the Evaluation of Fetal Anomalies of the Corpus Callosum: A Retrospective Analysis of 78 Cases Y Y Y Y Y Y N Y Y Y Y Y High quality Raafat RME. et al., 2020, Egypt, The prevalence and the adding value of fetal MRI imaging in midline cerebral anomalies Y Y Y Y Y Y Y Y Y Y Y Y High quality Turkyilmaz G. et al., 2019, Turkey, Utilization of neurosonography for evaluation of the corpus callosum malformations in the era of fetal magnetic resonance imaging Y Y Y Y Y Y U Y Y Y Y Y High quality Irwin K. et al., 2016, Australia, Utility of fetal MRI for workup of fetal central nervous system anomalies in an Australian maternal-fetal medicine cohort Y Y Y Y U Y U Y Y Y Y Y High quality Linh LT. et al., 2021, Vietnam, Detecting Fetal Central Nervous System Anomalies Using Magnetic Resonance Imaging and Ultrasound Y Y Y U Y N N Y Y Y Y Y Medium quality Raafat M. et al., 2021, Egypt, Fetal brain MRI: how it added to ultrasound diagnosis of fetal CNS anomalies-1 year experience Y Y Y Y Y Y U Y Y Y Y Y High quality Jarre A. et al., 2017, Spain, Value of brain MRI when sonography raises suspicion of agenesis of the corpus callosum in fetuses Y Y Y Y Y Y N Y Y Y Y Y High quality Kandula T. et al., 2015, Australia, Isolated ventriculomegaly on prenatal ultrasound: what does fetal MRI add? Y Y Y Y Y Y N Y Y Y Y Y High quality Mahmod M. et al., 2021, Egypt, The impact of adding fetal MRI to sonographically diagnosed intrauterine ventriculomegaly: a prospective cohort study Y Y Y U Y U U Y Y Y Y Y Medium quality Yilmaz E. et al., 2018, Turkey, Additional Findings from Fetal Magnetic Resonance Imaging for Prenatal Sonographic Diagnosis of Central Nervous System Abnormalities Y Y Y Y Y Y U Y Y Y Y Y High quality Ziaulhaq P. et al. 2020, India, The comparative study of antenatal magnetic resonance imaging and ultrasound in the evaluation of fetal central nervous system abnormalities Y Y Y Y N U N Y Y Y Y Y Medium quality Velipaşaoğlu M. et al. 2018, Turkey, Assessment of the Additional Value of Fetal Magnetic Resonance Imaging to Prenatal Ultrasound in a Single Institution Y Y Y Y N U N Y Y Y Y Y Medium quality Katz JA. et al. 2018, USA, Utility of prenatal MRI in the evaluation and management of fetal ventriculomegaly Y Y Y Y Y U U Y Y Y Y Y High quality Frick N. et al. 2015, Austria, The Reliability of Fetal MRI in the Assessment of Brain Malformations Y Y Y Y Y U U Y Y Y Y Y High quality Checklist for cohorts studies (1) Is the purpose of the study formulated? (2) Were subjects recruited for the cohort satisfactorily? (3) Was the exposure accurately measured? (4) Was the outcome accurately measured? (5) Have the authors identifi ed and/or taken into account all- important/known possible confounders in the design and analysis of the study? (6) Were any of the people in the cohort followed up? (7) Were the people followed up long enough? (8) What is the result of this study? (9) Do you trust the results? (10) Can the results be transferred to practice? (11) Do the results of this study fi t with the results of other available studies? (12) What are the implications of this study for practice? (Answers Yes: Y; No: N; Unclear: U) Medical Imaging and Radiotherapy Journal (MIRTJ) 38 (2) 9 Salkić E. et al./ Magnetic resonance imaging in the assessment of fetal central nervous system anomalies From the above assessment of the quality of studies with cohort design, it can be concluded that most of the studies used in this systematic review are in the category of high- quality studies (11 in total), with a smaller number of medium- quality studies (6 in total). Table 2 determines the importance of prenatal magnetic resonance imaging in making an accurate diagnosis and assessment of CNS anomalies after neurosonographically determined suspicions. Signifi cance was observed through several cases in which prenatal magnetic resonance imaging confi rmed the diagnosis of previously established suspicion on ultrasound. Even more signifi cant is the number of cases in which MRI changed the ultrasound diagnosis and thus established a fi nal, accurate diagnosis. It also ruled out certain cases of CNS anomalies and declared them a normal fi nding without the presence of anomalies. Also, the total percentage (%) for each group of the cases mentioned above is shown. Table 2. Signifi cance of prenatal magnetic resonance imaging in making an accurate diagnosis and assessment of central nervous system anomalies after neurosonographically determined suspicion Main author/ year of publication MRI confi rmed ultrasound diagnosis (n/%) MRI changed ultrasound diagnosis or added information (n/%) MRI ruled out ultrasound diagnosis (normal fi ndings) (n/%) UZ provided additional information for MRI (n/%) Tanacan A.et al./2020. 59/110 (53,6%) 13/110 (11,8%) 38/110 (34,6%) 0 Mazor MM. et al./2018. 50/78 (64,1%) 9/78 (11,5%) 19/78 (24,4%) 0 Raafat RME. et al./2020. 21/37 (56,8%) 16/37 (43,2%) ND 3/37 (8,1%) Turkyilmaz G. et al./2019. 33/36 (91,7%) 3/36 (8,3%) ND 0 Irwin K. et al./2016. 26/57 (45,6%) 31/57 (54,4%) 6/57 (10,5%) 0 Raafat M. et al./2021. 23/40 (57,5%) 6/40 (15%) NP 0 Jarre A. et al./2017. 38/78 (48,7%) 12/78 (15,4%) 28/78 (35,9%) 0 Mahmod M. et al./2021. 45/60 (75%) 1/60 (1,6%) ND 0 Ziaulhaq P. et al./2020. 9/23 (39,1%) 11/23 (47,8%) 2/23 (8,7%) ND 1/23 (4,4%) Frick N. et al./2015. 40/56 (71%) 12/56 (21,4%) 4/56 (7,1%) 0 Total percentage (%) 59,8% 20,2% 16,5% 0,8% (Notes and abbreviations (since several cases from these studies were used in Table 3, the total percentage in this table is below 100%; ND- no data) Sequence protocols on which the success of MRI detection itself depends and the importance of magnetic resonance imaging in making an accurate and precise diagnosis of CNS anomalies were also analyzed. Table 3 lists the primary data (magnetic fi eld strength, type of MRI device, sequences used, and sequence parameters) relevant to each study used in this review and related to magnetic resonance imaging of the fetal CNS. 10 Medical Imaging and Radiotherapy Journal (MIRTJ) 38 (2) Salkić E. et al./ Magnetic resonance imaging in the assessment of fetal central nervous system anomalies Table 3. Technical parameters based on which magnetic resonance imaging was performed Main author/year of publication Magnetic fi eld strength/ type of MRI device Sequence protocol The ENSO Group/2020. ND ND Tanacan A.et al./2020. 1,5 T Siemens T2W HASTE (TR/TE 2290/185ms, thickness 3mm); T1 FLASH (TR/TE 140/2,4; FA=70º); DWI (TR/TE 4800/116ms; bmax 600s/mm2 Sefi dbakht S.et al./2016. 1,5 T Siemens Avanto T2W HASTE and TRUFI SP (thickness 4-6mm); T1 FLASH Mazor MM. et al./2018. 1,5 T GE Optima T2W SSFSE (TR/TE 1298/90ms; matrix 320x224; FOV 24-30cm; thickness/ gap 3-4/0mm); spoiled T1 GRE(TR/TE 160/2,3ms; FOV 40cm; thickness/ gap 4/0,5mm); DWI (b= 0 and 1000 or 700s/mm2) Raafat RME. et al./2020. 1,5 T Philips Achieva XR T2W SSFSE; SSTSE; spoiled T1 GRE Turkyilmaz G. et al./2019. 1,5 T GE- Explorer T2W SSFSE (thickness 2-3mm); T1 WI Irwin K. et al./2016. 1,5 T Siemens Avanto T1, T2 (HASTE, FLASH), DWI (thickness 3-5mm) Linh LT. et al./2021. 1,5 T GE Signa HD T2W SSFSE in 3 planes; axial T1W and DWI Raafat M. et al./2021. 1,5 T Philips T2W B-FFE (TR/TE 3,5/1,7ms; matrix 256x256; FOV 300-400mm; thickness/ gap 5/0mm; FA=80º); T2W SSFSE (TR/TE 1500/120ms; matrix 169x256; FOV 200-300mm; thickness/gap 3-4/0,5mm; FA=90º); T1W (TR/TE 120/4ms; matrix 166x256; FOV 300mm; thickness/gap 5/0,5mm; FA=70º) Jarre A. et al./2017. 1,5 T Siemens Avanto1,5 T GE Signa Excite T2W FSE (HASTE/SSFSE) (thickness/gap 3/0,3mm); True Fisp/FIESTA (thickness/gap 4/0,4mm; FOV 260-320mm); EPI DWI (b=600s/mm2) Kandula T. et al./2015. 1,5 T Siemens Avanto T2W HASTE Mahmod M. et al./2021. 1,5 T Philips ND Yilmaz E. et al./2018. 1,5 T Siemens T2W HASTE (TR/TE 1200/91ms; matrix 192x256; thickness 3mm, FOV 207x100; FA 150º); axial T1 FLASH(TR/TE 199/4ms; matrix 134x256; thickness 4mm; FOV 300x75; FA 70º); sag and cor T1 FLASH in suspected bleeding and parenchymal lesions Ziaulhaq P. et al./2020. 3T Siemens Skyra T2W SSFSE; DWI (b=0-600s/mm2) Velipaşaoğlu M. et al./2018. 3T GE SSFSE (CUBE) sequence (ND) Katz JA. et al./2018. 1,5T and 3T GE T2W SSFSE sequence in 3 planes (ND) Frick N. Et al/2015. 1,0T Siemens 1,5T Ingenia Philips 3T Achiva Philips T2W SSFSE (TR/TE 2100/90ms; thickness 5mm; FOV 330x300mm; matrix 138x256; acquisition time 40s); T1W axial; TRUFI SP-sag; DWI; FLASH; FLAIR (rarely used sequences) Abbreviations: T (Tesla); DWI (diff usion weighted imaging); W (weighted); HASTE (Half-Fourier Acquired Single-shot Turbo spin Echo); FLASH (fast low angle shot); SSFSE (single shot fast spin-echo); TR/TE (time to repeat/time to echo); TRUFI SP (True FISP); FOV (Field of view); FA ( fl ip angle); GE (General Electric); GRE (gradient echo); SSTSE (single shot turbo spin-echo); B-FFE (Balanced Fast Field Echo); FIESTA (Fast Imaging Employing Steady-state Acquisition); EPI (Echo-planar imaging); WI (weighted imaging); sag (sagital); cor (coronal); FLAIR (fl uid attenuated inversion recovery ); ND (no data) Then, if additional anomalies detected only by magnetic resonance are considered, Table 4 was created for this purpose in which the incidence of fetal CNS anomalies missed on ultrasound imaging and diagnosed on magnetic resonance imaging was analyzed. Relevant data from 12 studies were used for this analysis, which off ered the exact number of cases in which MRI revealed additional anomalies missed on prenatal ultrasound. For easier analysis, in addition to the number of cases of additional anomalies, the table also lists the initial ultrasound suspicions or diagnoses and, most often, additional anomalies detected within each study by magnetic resonance Medical Imaging and Radiotherapy Journal (MIRTJ) 38 (2) 11 Salkić E. et al./ Magnetic resonance imaging in the assessment of fetal central nervous system anomalies Table 4. Anomalies of the central nervous system missed on ultrasound and detected by prenatal magnetic resonance imaging Main author/year of publication Initial ultrasound suspicion/ diagnosis Additional anomalies were identifi ed on MRI and missed on ultrasound (n / N /%) Most common additional anomalies (n) The ENSO Group/2020. Isolated mild or moderate VM 30/556; 5,4% ICH (8); polymicrogyria (6); lissencephaly (4); hypoplasia of CC (2) Sefi dbakht S.et al./2016. Suspicion of CNS anomalies / the most common indication of isolated VM 18/107; 16,82% DW variants (3); Chiari II malformation (3); PACC, CACC, aqueductal stenosis (2) Mazor MM. et al./2018. Suspicion of corpus callosum anomalies 22/78; 28,2% Calpocephaly (13); intrahemispheric cysts (4); ventricular asymmetry and gyration disorder (2) Turkyilmaz G. et al./2019. Suspicion of corpus callosum anomalies 3/36; 8,1% PFA (1); cortical malformations (2) Linh LT et al./2021. Suspicion of CNS anomalies 8/66; 12,1% Intracranial hemorrhage (6); vascular malformations (2) Raafat M. et al./2021. Suspicion of CNS anomalies 11/40; 27,5% Meningocele (4); polymicrogyria (2); PACC (2); vermian hypoplasia (2) Jarre A. et al./2017. Suspected agenesis of the corpus callosum 28/45; 62,2% VM (22); cortical malformations (15); PFA (7); midline malformations (3) Kandula T. et al./2015. Bilateral or unilateral VM 10/59; 17% ICH; lesions of the corpus callosum; periventricular anomalies; CSP anomalies (1) Mahmod M. et al./2021. Isolated ventriculomegaly 14/60; 23% CC and CSP lesions (29%); PFA (28%); cortical malformations (21%) Yilmaz E. et al./2018. Suspicion of CNS anomalies / the most common indication of VM 22/54; 40% Subependymal nodules (2); cortical tuber (2) Velipaşaoğlu M. et al./2018. The most common indication is isolated ventriculomegaly 12/50; 24% Posterior fossa defects (36,4%) Katz JA. et al./2018. All cases of ventriculomegaly 58/74; 78% Cortical anomalies; PFA; midline; additional vascular anomalies Total percentage (%) 19,3% Abbreviations: UZ (ultrasound), MRI (magnetic resonance imaging), CNS (central nervous system), VM (ventriculomegaly), ICH (intracranial hemorrhage), CC (corpus callosum), CSP (cavum septum pellucid), PFA (posterior fossa anomalies), DW (Dandy-Walker), CACC/PACC (complete/partial agenesis of corpus callosum) Finally, Table 5 depicts an analysis of the impact of prenatal magnetic resonance imaging on clinical decision-making and outcomes of central nervous system anomalies. Data from 7 studies were used for this analysis, which provided information on the number of cases of termination and continuation of pregnancy and data on neonatal death and the number of stillbirths. In several studies, some cases were lost for follow- up. In contrast, in others, postnatal MRI was not available, so only certain studies could compare their data with postnatal MRI data and provide information on the outcome of the anomalies. 12 Medical Imaging and Radiotherapy Journal (MIRTJ) 38 (2) Salkić E. et al./ Magnetic resonance imaging in the assessment of fetal central nervous system anomalies Table 5. The impact of prenatal magnetic resonance imaging on clinical decision making and outcomes of central nervous system anomalies Clinical outcomes ACCEPTABLE STUDIES Ta na ca n A . e t a l./ 20 20 . Tu rk yi lm az G . e t a l./ 20 19 . Irw in K . e t a l./ 20 16 . Ra af at M . e t a l./ 20 21 . Ja rr e A . e t a l./ 20 17 . Ka nd ul a T. e t a l./ 20 15 . Zi au lh aq P . e t a l. /2 02 0. Termination of pregnancy 14/72 12,7% 18/36 50% 11/57 19% 7/40 17,5% 21/30 47,7% 4/59 6,8% 7/23 30,4% Continuation of pregnancy ND 17/36 47,2% 46/57 81% 33/40 82,5% 9/30 20,5% 55/59 93,2% 16/23 69,6% Neonatal death 3/72 2,7% ND 1/46 2,2% 4/40 10% ND 3/55 5,5% ND Stillborn 2/72 1,8% 1/36 2,8% 2/46 4,3% 2/40 5% 1/9 11% ND ND Characteristics of the study Termination of pregnancy in 50% of cases of ACC Normal neurodevelopment in 8 cases and developmental delay expected in the remaining 8 cases Developmental delay in 14/43 cases; childbirth (33%) 27/40 (67.5%) studies resulted in childbirth In 8 live births, postnatal MRI confi rmed the prenatal diagnosis of ACC Greater MRI specifi city results in additional important information that can help advise parents on the clinical outcome, the likelihood of recurrence The study did not provide data on postnatal imaging and follow-up of patients Abbreviations: ND (No data), ACC (agenesis of corpus callosum), MRI (magnetic resonance imaging) DISCUSSION In the 10 studies applied in Table 2 and 575 cases, MRI confi rmed the ultrasound diagnosis in 59.8% of cases. In contrast, in 20.2% of cases, it changed the diagnosis established on ultrasound, or in 16.5% of cases in which ultrasound established the diagnosis, MRI confi rmed the normal fi nding. Our results are consistent with the results of the study conducted by Jarvis D. and colleagues (32), who in their meta-analysis confi rmed the agreement of ultrasound and magnetic resonance imaging in 55% of cases; discrepancy in 23% of cases and 25% of cases in which ultrasound established the diagnosis, MRI confi rmed the normal fi nding. Also, Van Doorn M. and colleagues (33) noted in 65% of cases the agreement of these two modalities; in 26% of cases, MRI provided additional or diff erent pathology, and 12% rejected ultrasound diagnosis. In our study, only 2/10 of the studies, conducted by Raafat RME et al., and Ziaulhaq P. et al. (19,28), provided data in which ultrasound provided additional information to magnetic resonance imaging. These rates were 8.1% (19) and 4.3% (28) and mainly related to facial abnormalities and restriction of intrauterine growth, which can be explained as technological advances in ultrasound and the skills of the radiologist performing the examination. While Rossi AC. and colleagues (34) in their study recorded only 2% of cases in which ultrasound was more accurate than MRI. Consequently, based on the data from Table 3, it is possible to conclude that a 1.5T MRI device was most often used to record the fetal CNS, while 3T devices were used in our work in only 4/17 studies. As the best protocol based on the data off ered by our studies, we can accept the one that contains the fi rst SSFSE (HASTE) T2 weighted sequences in the sagittal, coronal and axial planes, as they are key to reducing fetal movement (thus reducing artifacts). In addition, most studies as additional sequences, and depending on the indications themselves, most often used T1 weighted sequences (FLASH, GRE) in the axial plane, which proved to be the best for detecting bleeding, fat and calcifi cations or myelin; and DWI sequences in the axial plane which, as an advanced technique, enable the distinction between developmental and destructive pathologies. Based on our results in Table 4, anomalies missed on ultrasound and detected on MRI occurred in 236/1225 cases, totaling 19.3% of additional anomalies. The most common additional anomalies were: intracranial hemorrhage; cortical anomalies, medial anomalies; and PFA. This rate of additional Medical Imaging and Radiotherapy Journal (MIRTJ) 38 (2) 13 Salkić E. et al./ Magnetic resonance imaging in the assessment of fetal central nervous system anomalies anomalies in the study conducted by Reda AM. and colleagues (35) was slightly higher, 22.5%. Also, studies conducted by Jarvis D. and colleagues and Rossi AC. and colleagues (32,34) were reported additional information provided by MRI in 15% and 22.1% of cases, respectively. Most authors claim that the risk of fi nding additional CNS abnormalities in fetuses with isolated ventriculomegaly is high and that it increases with the increasing severity of ventriculomegaly (36,37). This confi rms that in 7/12 of the studies used in Table 4, with a signifi cant incidence of associated anomalies, the initial suspicion or diagnosis on ultrasound was precisely ventriculomegaly. This is also supported by the study results conducted by Di Mascio D. and colleagues (37), who reported 3.5% and 22.6% of associated anomalies detected on MRI and missed on ultrasound in fetuses with isolated mild, that is, moderate ventriculomegaly. The detection of these additional anomalies by MRI indicates its importance in making clinical decisions and enabling parents to make a more conscious decision about their pregnancy. All of our 7 studies from Table 5 were provided information on the number of terminations of pregnancy that occurred in 82/317 cases, accounting for 25.9%. One study that was used did not provide data on the continuation of pregnancy, so based on the remaining studies, the pregnancy was continued in a total of 176 cases. Data on neonatal deaths were not available in the 3 studies used, and 11 cases of neonatal death were recorded in other studies. The number of stillbirths or deaths after birth was reported in 8 cases, as 2 studies did not provide data. Di Mascio D. and colleagues (37) sought to determine whether the detection of associated anomalies by MRI led to a change in prenatal management of pregnancy due to a higher risk of abnormal neurodevelopment outcomes. They proved that 4.6% of fetuses who had an isolated VM on ultrasound and then an additional anomaly on MRI had a signifi cant change in perinatal treatment (mostly termination of pregnancy at the parents' request). Furthermore, in their study Mazor MM. and colleagues (18) state that MRI contributed to a change in management of pregnancy for 28 fetuses (35.9%), of which 25 fetuses (32.1%) are in favor of preserving pregnancy. CONCLUSION Ultrasound is the standard way of recording anomalies in the second and third trimesters. Still, MRI using T2W SSFSE sequences in 3 planes, T1W and DWI in the axial plane, is a complementary modality to prenatal ultrasound in making an accurate diagnosis and assessment of CNS anomalies off ering a signifi cant percentage of change cases or complete exclusion of previously established ultrasound suspicion. The incidence of additional detected CNS anomalies on magnetic resonance imaging, which were previously missed on ultrasound, indicates the benefi t of performing the same in cases when ultrasound examination is unclear or incomplete and when these additional anomalies are far beyond the range and ability of ultrasound to diagnose them. Finally, prenatal MRI with the diagnosis of associated / additional CNS abnormalities may infl uence clinical decision-making regarding the continuation or termination of pregnancy and, fi nally, the preparation of family and clinicians for postnatal care depending on the presence or absence of abnormal neurodevelopmental outcomes. LITERATURE 1. Vegar-Zubović S, Behmen A, Bektesević H, Prevljak S, Džananović A, Bukvić M. et al. Magnetic Resonance Imaging in the Diagnosis of Fetal Pathology. Acta Inform Med. 2019;27(1):50-53. 2. Werner H, Gasparetto TD, Daltro P, Gasparetto EL, et Júnior EA. Typical lesions in the fetal nervous system: correlations between fetal magnetic resonance imaging and obstetric ultrasonography fi ndings. Ultrasonography. 2018;37(3):261–274. 3. Verburg B, Fink AM, Reidy K, Palma-Dias R. The Contribution of MRI after Fetal Anomalies Have Been Diagnosed by Ultrasound: Correlation with Postnatal Outcome. Fetal Diagnosis and Therapy 2015;38(3):186-194. 4. Schneider JF. Case series: Fetal* MR imaging of the brain at 3T. Clinical fetal imaging. MAGNETOM Flash. 2011;100- 104. [accessed 02.10.2021]. Available from: http:// www. siemens. com/magnetom-world. 5. Cater SW, Boyd BK, Ghate SV. Abnormalities of the Fetal Central Nervous System: Prenatal US Diagnosis with Postnatal Correlation. Radiographics. 2020;40(5):1458- 1472. 6. Stamenković J. Poremećaji fetalnog rasta i razvoja: Mogućnosti ultrazvučne dijagnostike u proceni postnatalnog ishoda anomalija centralnog nervnog sistema. Udruženje za fetalnu i neonatalnu medicinu. Beograd. 2016;8-13. 7. Novakov-Mikić A, Ljubić A. Razvijanje regionalnog prekograničnog sistema dijagnostičkih centara za prenatalnu dijagnostiku fetalnih malformacija na području Temišvara i Vršca. Vršac: Opšta bolnica Vršac. 2014;5-8. 8. Tee LMF, Kan EYL, Cheung JCY, Leung WC. Magnetic resonance imaging of the fetal brain. Hong Kong Med J. 2016; 22(3):270–278. 9. Girard N, Chaumoitre K. Prenatal Diagnosis by Fetal Magnetic Resonance Imaging. Genetic Disorders and the fetus. 2015;660-680. 10. Reith W, Haussmann A. et Yilmaz U. Fetal Magnetresonanztomographie. Der Radiologe. 2018;58(7);668-672. 11. Jokhi RP, Whitby EH. Magnetic resonance imaging of the fetus. Developmental Medicine and Child Neurology. 2010;53(1):18-28. 12. Jarvis D.A, Griffi ths P.D. Current State of MRI of the Fetal Brain In Utero. Journal of Magnetic Resonance Imaging. 2019;49:632–646. 13. Julardžija F, Šehić A, Hasanbegović A, Voloder E, Nikšić M, Merhemić Z. Magnetna rezonanca u ranom otkrivanju anomalija centralnog nervnog sistema. Radiološke tehnologije. 2011;4:35-37. 14 Medical Imaging and Radiotherapy Journal (MIRTJ) 38 (2) Salkić E. et al./ Magnetic resonance imaging in the assessment of fetal central nervous system anomalies 14. National Heart, Lung, and Blood Institute (NHLBI). Study Quality Assessment Tools. [internet]. 2013 [accessed 02.10.2021]. Available at: https://www.nhlbi.nih.gov/ health-topics/study-quality-assessment-tools 15. The ENSO Working Group. Role of prenatal magnetic resonance imaging in fetuses with isolated mild or moderate ventriculomegaly in the era of neurosonography: international multicenter study. Ultrasound Obstet Gynecol. 2020;56(3):340-347. 16. Tanacan A, Ozgen B, Fadiloglu E, Unal C., Oguz K.K., Beksac M.S. Prenatal diagnosis of central nervous system abnormalities: Neurosonography versus fetal magnetic resonance imaging. Eur J Obstet Gynecol Reprod Biol. 2020.;250:195-202. 17. Sefi dbakht S, Dehghani S, Safari M, Vafaei H, Kasraeian M. Fetal Central Nervous System Anomalies Detected by Magnetic Resonance Imaging: A Two-Year Experience. Iranian Journal of pediatrics. 2016; 26 (4):e4589. 18. Mazor MM, Brenner AW, Yosef OB, Hoff mann C, Mazor RD, Mosheva M. et al. Added Value of Fetal MRI in the Evaluation of Fetal Anomalies of the Corpus Callosum: A Retrospective Analysis of 78 Cases. Ultraschall Med. 2018;39(5):513-525. 19. Raafat RME, Abdelrahman TM, Hafez MAF. The prevalence and the adding value of fetal MRI imaging in midline cerebral anomalies. Egyptian Journal of Radiology and Nuclear Medicine. 2020;51:31. 20. Turkyilmaz G, Sivrikoz TS, Erturk E, Ozcan N, Tatlı B, Karaman B. et al. Utilization of neurosonography for evaluation of the corpus callosum malformations in the era of fetal magnetic resonance imaging. J Obstet Gynaecol Res. 2019;45(8):1472-1478. 21. Irwin K, Henry A, Gopikrishna S, Taylor J, Welsh AW. Utility of fetal MRI for workup of fetal central nervous system anomalies in an Australian maternal-fetal medicine cohort. Aust N Z J Obstet Gynaecol. 2016;56(3):267-73. 22. Linh LT, Duc NM, Nhung N-TH, My T-TT, Luu DT, Lenh B.V. Detecting Fetal Central Nervous System Anomalies Using Magnetic Resonance Imaging and Ultrasound Med Arch. 2021; 75 (1):45-49. 23. Raafat M, Alalfy M, Nagy O, Saraya S. Fetal brain MRI: how it added to ultrasound diagnosis of fetal CNS anomalies-1 year experience. Egypt J Radiol Nucl Med. 2021; 85(52). 24. Jarre A, Salvador RL, Fornas GM, Filardi AM. Value of brain MRI when sonography raises suspicion of agenesis of the corpus callosum in fetuses. Radiologia. 2017; 59 (3):226- 231. 25. Kandula T, Fahey M, Chalmers R, Edwards A, Shekleton P, Teoh M. et al. Isolated ventriculomegaly on prenatal ultrasound: what does fetal MRI add?. J Med Imaging Radiat Oncol. 2015; 59(2):154-62. 26. Mahmod M, Ragaee SM, Hamed ST., Abbas A., Mourad MA. The impact of adding fetal MRI to sonographically diagnosed intrauterine ventriculomegaly: a prospective cohort study. Proc Obstet Gynecol. 2021;10(2):13. 27. Yilmaz E, Bakir B, Kalelioglu HI, Yuksel A, Has R, Tatli B. et al. Additional Findings from Fetal Magnetic Resonance Imaging for Prenatal Sonographic Diagnosis of Central Nervous System Abnormalities. Eurasian Journal of Medicine and Investigation EJMI 2018;2(3):111–117. 28. Ziaulhaq P, Khan NA, Banday S. The comparative study of antenatal magnetic resonance imaging and ultrasound in the evaluation of fetal central nervous system abnormalities. CHRISMED J Health Res 2020;7(3):188-192. 29. Velipaşaoğlu M, Şaylısoy S, Öcal E, Tanır H. Assessment of the Additional Value of Fetal Magnetic Resonance Imaging to Prenatal Ultrasound in a Single Institution. Osmangazi Tıp Dergisi. 2018;40(2):47-52. 30. Katz JA, Chock VY, Davis AS, Blumenfeld YJ, Hahn JS, Barnes P. Utility of prenatal MRI in the evaluation and management of fetal ventriculomegaly. Journal of Perinatology. 2018;38 (11):1444-1452. 31. Frick N, Fazelnia C, Kanzian K, Hitzl W, Fischer T, Forstner R. et al. The Reliability of Fetal MRI in the Assessment of Brain Malformations. Fetal Diagnosis and Therapy. 2015; 37(2):93–101. 32. Jarvis D, Mooney C, Cohen J, Papaioannou D, Bradburn M, Sutton A, et al. A systematic review and meta-analysis to determine the contribution of mr imaging to the diagnosis of foetal brain abnormalities In Utero. European Radiology. 2016;27 (6):2367-2380. 33. Van Doorn M, Rengerink KO, Newsum EA, Reneman L, Majoie CB, Pajkrt E. Added value of fetal MRI in fetuses with suspected brain abnormalities on neurosonography: a systematic review and meta-analysis, The Journal of Maternal-Fetal & Neonatal Medicine. 2015;1-13. 34. Rossi AC, Prefumo F. Additional value of fetal magnetic resonance imaging in the prenatal diagnosis of central nervous system anomalies: a systematic review of the literature. Ultrasound Obstet Gynecol 2014;44:388–393. 35. Reda AM, Ali REM, Salem HAA, El-Shafey KE. Added Value of Fetal Magnetic Resonance Imaging in Diagnosis of Central Nervous System Congenital Anomalies in Egyptian Population. International Journal of Medical Imaging. 2018;6(4):40-48. 36. Yazbek S, Grant PE. Fetal Brain MRI: Patterned Approach and Review. Neurographics. 2015;5(5):181-191 37. Di Mascio D, Sileo FG, Khalil A, Rizzo G, Persico N, Brunelli R. et al. Systematic review and meta-analysis on the role of prenatal magnetic resonance imaging in the era of fetal neurosonography: mild and moderate ventriculomegaly. Ultrasound in obstetrics and gynecology. 2018;1-10 Medical Imaging and Radiotherapy Journal (MIRTJ) 38 (2) 15 Review article MRI SAFETY AND MANAGEMENT OF PATIENTS WITH CARDIOVASCULAR IMPLANTABLE ELECTRONIC DEVICES: LITERATURE REVIEW AND CASE PRESENTATION MAGNETNORESONANČNA VARNOST IN OBRAVNAVA PACIENTOV Z VSTAVLJENIMI KARDIOVASKULARNIMI ELEKTRONSKIMI NAPRAVAMI: PREGLED LITERATURE IN ŠTUDIJA PRIMERA Matic GODEC*, Jani IZLAKAR, Gašper PODOBNIK * Corresponding author: matgodec@onko-i.si Received: 30. 12. 2021 Accepted: 26. 7. 2022 https://doi.org/10.47724/MIRTJ.2021.i02.a002 Medical Imaging and Radiotherapy Journal (MIRTJ) 38 (2) ABSTRACT Introduction: MRI has long been contraindicated in patients with CIED devices due to the risk of adverse eff ects through electromagnetic interference. Recent developments in engineering have led to the introduction of MRI conditional CIED devices that do not cause signifi cant clinical harm to patients undergoing MRI, when specifi c imaging conditions are met. Safe access to MRI has become a crucial need for patients with CIED devices. Aim: The purpose of this paper is to present an overview of how to manage patients with implanted CIED devices and to present a case report of a patient with CIED undergoing prostate MRI examination. Methods: This paper explores MRI Safety and the management of patients with implanted CIED devices through an extensive literature review and case presentation. The literature search was conducted using medical scientifi c electronic databases such as PubMed, Cinahl, Wiley Online Library and ScienceDirect. We examined a patient with a CIED device undergoing a prostate MRI examination. Results and discussion: We performed an examination of the described patient in accordance to the guidelines presented in this paper. The MR conditionality status was determined using the device identifi cation card and the manufacturer’s technical manual. The MRI examination of the patient was completed without complications; therefore, no adverse eff ects were reported. The MRI images were without artefacts. Conclusion: Recent clinical studies and published guidelines suggest that MRI of the patients with either an MRI conditional or MRI non-conditional CIED device is relatively safe under specifi c conditions. Multidisciplinary pre-procedure planning, a strict screening process, monitoring and device evaluation protocols are of key importance for ensuring safe MRI imaging in patients with CIED. IZVLEČEK Uvod: Magnetna resonanca je dolgo časa veljala za absolutno kontraindikacijo pri MR preiskavah pacientov z vstavljenimi CIED napravami. Tehnološki napredek na področju razvoja CIED naprav je doprinesel k uveljavitvi MR pogojno varnih kardiovaskularnih elektronskih naprav v kliničnem okolju. MR pogojno varne CIED naprave ne predstavljajo kliničnega tveganja za paciente s tovrstnimi napravami, če so upoštevani specifi čni pogoji uporabe. Varna izvedba MR slikanja je postala ključnega pomena pri zdravljenju tovrstnih pacientov. Namen: Namen te raziskave je predstaviti pregled področja obravnave pacienta z vstavljeno CIED napravo med MR slikanjem in predstaviti primer MR slikanja prostate pri pacientu s CIED napravo. Metode: V študiji smo predstavili pregled literature na področju MR varnosti in obravnave pacientov z vstavljenimi CIED napravami. Predstavili smo tudi primer obravnave MR slikanja prostate pri pacientu s CIED napravo. Literaturo smo zbirali s pomočjo elektronskih podatkovnih baz PubMed, Cinahl, Wiley Online Library in ScienceDirect. Rezultati in razprava: Preiskavo smo izvedli v skladu s priporočili, predstavljenimi v tem dokumentu. MR status naprave smo ugotovili na podlagi pregleda identifi kacijske kartice naprave in proizvajalčevih priporočil o uporabi naprave v MR okolju. Preiskava je bila opravljena brez kliničnih zapletov. Na MR slikah ni bilo prisotnih popačenj zaradi prisotnosti CIED naprave. Zaključek: Najnovejše klinične študije in izdana priporočila ugotavljajo, da je MR slikanje pacientov s CIED napravami relativno varno v specifi čnih pogojih ne glede na to, ali gre za MR pogojno varne naprave ali ne. Ključnega pomena pri zagotavljanju varnosti pri MR preiskavah tovrstnih pacientov je predhodno multidisciplinarno načrtovanje preiskave, natančen varnostni pregled/screening pacienta, kakovosten nadzor nad pacientom med preiskavo in ocena delovanja naprave po preiskavi. 16 Medical Imaging and Radiotherapy Journal (MIRTJ) 38 (2) Godec M. et al./ MRI safety and management of patients with cardiovascular implantable electronic device ... INTRODUCTION Magnetic Resonance Imaging (MRI) is a non-ionizing radiation dependant imaging modality that provides excellent soft tissue spatial resolution. MRI has long been contraindicated in patients with cardiovascular implantable electronic devices (CIED) due to the risk of adverse eff ects through electromagnetic interference (1). Recent developments in engineering have led to the introduction of MRI conditional CIED devices that do not cause signifi cant clinical harm to patients undergoing MRI when specifi c imaging conditions are met (2). Classifi cation of CIED CIED is a term that comprises pacemakers (PPM), implantable cardioverter defi brillators (ICD) and cardiac resynchronization therapy devices (CRT). CIED system traditionally consist of two components – the pulse generator and thin insulated wires called leads (3). These devices have proven to be an invaluable tool in the practice of cardiology and treatment of a variety of cardiac arrhythmias. They can be divided further based on the functionality of the device and lead placement in the human heart. Therefore, we diff erentiate among single chamber CIED devices, dual chamber devices and biventricular (triple chamber) devices (4). Single chamber devices consist of a single lead that attaches either to the right atrium or right ventricle. Dual chamber devices use two leads that are placed in the right atrium and right ventricle. Biventricular CIED devices are divided into two groups: CRT-P devices, which stands for Cardiac Resynchronization Therapy Pacemaker and CRT-D devices, that stands for Cardiac Resynchronization Therapy Defi brillator. Biventricular devices deliver small electrical impulses to the left and right ventricle. Leads are placed into the right atrium, right ventricle and coronary sinus. The latter delivers electrical impulses to the left ventricle (3,5). Recently a new type of CIED device has been introduced for clinical use. Leadless pacemakers were designed to eliminate some of the complications associated with transvenous pacemakers and leads: pocket infection, hematoma, lead dislodgement and lead fracture. The device is 90% smaller than the transvenous system and it consists of a small cylindrical capsule that contains a battery, an electronic control unit and a single tip electrode. The leadless pacemaker is implanted into the right ventricle myocardium via a femoral vein transcatheter approach. The downside of this device is that it provides only single-chamber ventricular pacing and lacks defi brillation capacity (3,6,7). MRI Safety Labelling of CIED Safe access to MRI has become a crucial need for patients with CIED devices. An estimated 50-75% of these patients may have a clinical indication to undergo MRI after the implantation over their lifetime. For this reason, new generations of cardiovascular implantable electronic devices have been designed to allow such patients to safely undergo MRI provided that specifi c conditions are met during the scan (8). CIED devices that are labelled as MRI conditional need to be tested in a specifi c MRI environment, including induced torque and force, current induction, RF heating and potential electromagnetic interference. MRI conditional labelling for CIED devices generally includes requirements for static magnetic fi eld strength, maximum spatial fi eld gradient, maximum gradient slew rate, maximum specifi c absorption rate-SAR or an alternative RF exposure parameter such as B1+RMS (root mean square of the fl ip angle). The conditions of safe use also specify the confi guration of the device, allowed implant locations, device reprogramming requirements during the scan, exclusion zones, specifi c patient monitoring demands and required staff for device programming and monitoring. Cardiovascular implantable electronic devices that do not meet the criteria for MRI conditional labelling are considered as non-MRI-conditional. This classifi cation includes CIED devices that have one system component labelled as MR Conditional and the other component as non-MR conditional. For example, a system that has a pulse generator labelled as MRI conditional and pacing leads that do not have MRI- conditional labelling is considered as non-MRI-conditional (2,9). Interactions of MRI environment with CIED The interaction of the MRI environment with CIED systems has been the root cause of a historical contraindication to the presence of a cardiovascular implantable electronic device in patients undergoing MRI. These interactions include translational attraction or torque on device components due to the spatial magnetic fi eld gradient (8). The magnitude of the translational force will vary based on the position of the device in the MRI scanner. Stronger translational forces are exerted on the device just outside the scanner bore. However, torque is strongest in the isocenter of the MRI scanner (10). Figure 1: The schematic of excerted translational forces and torque on a CIED relative to the position in the scanner (10). Radiofrequency pulses can cause ohmic heating via tissue absorption of the energy. This is measured using the specifi c absorption rate-SAR or an alternative method referred to as the root mean square of the fl ip angle B1+RMS. SAR is a measure of the amount of RF energy the MR scanner produces and that may be absorbed by the tissue. The American Food and Drug Administration approves two SAR levels during an MRI examination; normal operating mode (≤ 2 W/kg whole-body SAR) and fi rst-level mode (≤ 4 W/kg whole-body SAR). The specifi c absorption rate is a patient dependant measurement of RF energy deposit and SAR calculations vary between diff erent MRI scanner vendors. The alternative method for estimating the applied RF energy is the time-averaged RF magnetic fi eld measurement called root-mean-square or B1+RMS. Root-mean-square is solely dependent on the MRI exam parameters and not patient specifi c parameters such Medical Imaging and Radiotherapy Journal (MIRTJ) 38 (2) 17 Godec M. et al./ MRI safety and management of patients with cardiovascular implantable electronic device ... as height, weight, age and gender. It is calibrated by the MR system software during the pre-scan phase or measurements. Pacemaker leads can concentrate RF energy at their tip and potentially cause excessive heating, which can lead to damage of the local myocardium. In the literature, this occurrence is referred to as the antenna eff ect, where continual rotation of RF in a polarized magnetic fi eld generates an electric fi eld by Faraday’s law of induction. This leads to the concentration of RF energy at the tip of the pacemaker lead. Gradient magnetic fi elds can induce a current in electrically conductive wires by turning on and off , which can result in myocardial stimulation (9-13). Potential hazards to the patient with CIED Initial reports of deaths in patients with CIED who were undergoing MRI are related to the absence of appropriate screening, reprogramming and patient monitoring. These reports, dating back to the late 1980s and early 2000s, contributed to the theory that CIEDs and the MRI environment were not compatible, and, therefore, were contraindicated. Other signifi cant adverse events commemorated in early experience reports are dislodgements or movement of the device, radiofrequency heating of the hardware and surrounding tissue, activation of tachycardia therapies and increased pacing thresholds (14,15,16). Over the past two decades, CIEDs have been designed to reduce the potential risks associated with MRI. Preclinical and clinical studies of newer generation devices show that many issues noted with older devices are no longer present. Modern devices contain less ferromagnetic materials and better electromagnetic interference protection, resulting in a signifi cantly lower rate of adverse events during the MRI examination (14,17). The European Heart Rhythm Association consensus on the prevention and management of interference due to medical procedures in patients with CIEDs has listed the possible eff ects of electromagnetic interference on these devices. Possible eff ects include inappropriate automatic mode switching, modifi cation of measured pacing/sensing thresholds, over-sensing related adverse events, sudden battery depletion and power-on reset (16). Power-on reset is a specifi c type of reprogramming that reverts the device to the factory default settings when the battery voltage falls below a critical level (15). Recent clinical studies evaluated the safety of MRI examinations in patients with CIEDs according to the incidence of the mentioned possible eff ects. The MagnaSafe Registry was a prospective, multicentre study that was established to determine the frequency of cardiac- related clinical events and device setting changes among patients with non-MRI-conditional devices who underwent nonthoracic MRI at 1.5T magnetic fi eld strength. It is the largest published registry that examined the outcomes of 1,500 patients with non-MRI-conditional CIEDs. Substantial changes in the device setting were infrequent and did not result in clinically adverse events; moreover, no device or lead failure was reported (18,19). Similar fi ndings are presented in the systematic review and meta-analysis done by Munawar et al., that included 35 studies of non-conditional CIEDs in the MRI environment. The rate of adverse events was the highest in regards to signifi cant changes in pacing lead impedance (incidence of 4.8%) and battery voltage (incidence of 2.2%). Findings of this meta-analysis are in accordance with the growing number of studies (1,11,15,18-25) demonstrating that comparatively minor device alterations such as a slightly depleted battery or altered pacing thresholds do not result in signifi cant adverse outcomes. While there is a growing body of evidence supporting the safety of MRI in patients with conditional and non-MRI- conditional devices, the evidence base supporting the safety of thoracic MRI examinations in such patients is limited to few single-centre studies (26-28). These studies demonstrate that with adherence to a standardized protocol and established exclusion criteria, thoracic MRI examinations in patients with CIEDs can safely be performed without clinically signifi cant changes of device functions or adverse outcomes. Recommendations for the management of patients with implanted MRI-conditional devices undergoing MRI (2,9,16,29). 1. Confi rm the need for MRI: evaluate the risk-benefi t ratio before making the decision to perform MRI on a patient with a CIED device. Factors that infl uence the risk-benefi t ratio should be identifi ed and discussed with the team of electrophysiologists and radiologists. 2. Determine whether the CIED system meets the MRI conditionality requirements. CIED systems that combine individual MR conditional leads and other device components from diff erent manufacturers should be regarded as non-MRI-conditional. Another indicator of a non-MRI-conditional system is the presence of abandoned leads, extenders or adaptors, lead remnants or fractured leads. 3. Identify the manufacturer’s specifi c instructions for safe use in the MRI environment. Manufacturer’s instructions include a full evaluation of the CIED and leads. Conditions of safe use can include the region being scanned and associated exclusion zones, scanning parameter restrictions and active reprogramming of the device before and after the scan. In general, the majority of devices have been approved for scanning with 1.5T, gradient slew rate≤200 T/m/s, a maximal SAR ≤2 W/kg or alternative RF exposure parameter (B1+RMS), and a limited number and length of imaging sequences. 4. Reprogramme the CIED system to one of the available company-specifi c pre-programmed settings. Pacing should be programmed to an asynchronous mode (VOO/DOO). Anti-tachycardia therapies and automated specialized algorithms must be switched off for all types of devices (16,29). 5. Monitor the patient using continuous real-time ECG and pulse oximetry. Device reprogramming can potentially impact the patient’s rhythm status. For example, untreated tachyarrhythmia or absence of bradycardia pacing can occur. Therefore, it is recommended that ECG and pulse oximetry monitoring is continued until clinically appropriate CIED settings are restored. During the scan, professional oversight should be sought for the duration of time that the patient’s device is reprogrammed. This professional oversight should be performed by personnel with the skill to perform advanced cardiac life support, including expertise in the performance of CPR, arrhythmia recognition, defi brillation, and transcutaneous pacing (2,29). 18 Medical Imaging and Radiotherapy Journal (MIRTJ) 38 (2) Godec M. et al./ MRI safety and management of patients with cardiovascular implantable electronic device ... Recommended guidelines for non-MRI-conditional systems (2,9,16,29) 1. Confi rm the need for an MRI scan. 2. Identify the MRI conditional status of the implanted device. Mind the presence of any abandoned, fractured or temporary pacing leads. 3. Determine whether the patient is pacing dependant or not. Patient pacing dependency is defi ned by the intrinsic heart rate. Pacing dependant patients are defi ned by an intrinsic heart rate below 50 beats per minute or by hemodynamic instability or symptoms of presyncope with device turndown (16,20). Reprogramming of the device should be based on this information. 4. Interrogate and reprogramme the device. Device interrogation include measures of lead impedance, pacing threshold, sensing amplitude and P- and R-wave amplitude. Pre and post MRI measures of this device parameters should not alternate. The cardiac electrophysiology team should determine the appropriate pacing mode for the patient. For patients who are not pacing dependant, it is required to reprogramme the device to either a nonpacing mode (ODO/OVO/OAO) or an inhibited mode (DDI/VVI/ AAI). For patients that are pacing dependant, the required pacing mode will most likely be an ansynchronous mode (DOO/VOO/AOO) that does not compete with the intrinsic rate. Anti-tachycardia therapies and automated specialized algorithms must be switched off for all types of devices (2,29,30). 5. MRI is limited to 1.5T, using Normal Operating Mode for SAR. Local transmit/receive coils may only be used if they are not positioned directly over the CIED device. The gradient magnetic fi eld slew rate is limited to ≤ 200T/m/s, the root mean square of the fl ip angle must not exceed 2.8μT (B1+RMS ≤ 2.8μT). The number and length of sequences should be minimized. 6. Monitor the patient using continuous real-time ECG and pulse oximetry. It is recommended that ECG and pulse oximetry monitoring is continued until clinically appropriate CIED settings are restored (2,29). 7. The CIED device should be reprogrammed to its original settings. Evaluate the device parameters as listed above (section 4). All changes in the device parameters and any adverse events, if observed, should be documented in the patient’s medical record. Implementation notes: A. Patient monitoring hardware: It should be noted that although continuous monitoring of the cardiac rhythm is the primary objective, the electrocardiogram (ECG) might not be interpretable during the use of many MRI sequences. ECG and peripheral gating waveforms displayed on the MRI console are not suffi cient for robust physiologic monitoring. Therefore, a dedicated MRI conditional patient monitoring system is likely required. Transcutaneous pulse oximetry which is relatively unaff ected during MRI sequences can confi rm a change in pulse rate in the absence of a technically adequate ECG signal (2,9,16,29). B. Personnel requirements: Personnel who perform the interrogation of the CIED device prior and post scan, the evaluation of the patient and monitoring of the patient during the scan are required to complete basic and advanced life support training (BLS and ACLS). An external defi brillator should be located just outside Zone III. The institution must have a written plan for managing the patient, including immediate evacuation to this location in the event of a cardiac emergency. For patients that require higher level monitoring (pacing dependant patients) it is recommended that a cardiac electrophysiologist is present during the MRI study (2,9). C. Presence of abandoned leads: Signifi cantly higher heating in abandoned leads compared with leads terminated at the pulse generator have been discovered in some phantom studies. Currently, available guidelines do not provide specifi c recommendations for abandoned leads (2,16,29). However, the 2017 Heart Rhythm Society consensus does not exclude imaging of these patients when the clinical indication exists (29). D. Pacing modes: Cardiovascular implantable electronic device pacing modes are denoted with a three-letter code. The fi rst letter describes which area/chamber is being paced and the second letter stands for the area/chamber being sensed. The third letter describes how the device responds when a beat is being sensed. For example, in VOO (asynchronous mode) pacing, the ventricle is paced at the fi xed rate with no device sensing. Therefore, the device paces at the programmed rate regardless of the intrinsic electrical activity of the heart (31). Figure 2: Types of pacing modes for CIED. AIM The purpose of this paper is to present an overview of the literature-based management of patients with CIED devices and to present a case of a patient with a CIED with exclusion zone requirement during a prostate MRI examination at our institution. METHODS This paper explores the MRI safety and managing of patients with implanted CIED devices through an extensive literature review and case presentation. The study was approved by the ethics committee of the Oncology Institute Ljubljana, Slovenia (research permission number: ERIDNPVO-0058/2022). The literature search was conducted using medical scientifi c electronic databases such as PubMed, Cinahl, Wiley Online Library and ScienceDirect during the period from January to Medical Imaging and Radiotherapy Journal (MIRTJ) 38 (2) 19 Godec M. et al./ MRI safety and management of patients with cardiovascular implantable electronic device ... April 2022. The search used keywords of “magnetic resonance imaging” AND “pacemaker” OR “implantable cardioverter defi brillator” OR “cardiac resynchronization therapy” OR “CIED”. The search was limited to articles in the English language and human studies. Published studies were reviewed manually for proposed diagnostic pathways/protocols, practice recommendations, guidelines and published manuals on MRI safety of CIED devices. Clinical studies were included if the following criteria were met: enrolment of patients with conditional and non-conditional CIEDs undergoing MRI, assessment of device alterations and adverse outcomes. Articles published before 2010 and clinical studies that included fewer than 10 patients were excluded from the review. The BIOTRONIK ProMRI technical manual was acquired using the Magresource online database that stores the MRI safety status of the implantable medical devices. Case presentation We examined a 52-year-old patient with a CIED device undergoing a classic prostate MRI examination. The scan was performed with a GE Optima™ MR450w 1.5T scanner using an anterior phased array for the pelvic region. The implanted device was a combination of a triple chamber pacemaker model called Entovis HF non-US and a lead model Solia S 53. The Biotronik ProMRI technical manual labelled this combination as MR conditional, under specifi c conditions. The permissible positioning zone had to be maintained during the MRI scan, denoting that the isocenter of the high-frequency coil had to be at the level of the greater trochanter for the duration of the scan. Other specifi c conditions included the limitation of the mean specifi c absorption rate to 2W/kg, limitation of the maximum slew rate (<200T/m/s) and use of a clinical MRI scanner with a closed bore, cylindrical magnets, and a static magnetic fi eld strength of 1.5 T. RESULTS AND DISCUSSION We performed the examination of the described patient in accordance with the guidelines presented in this paper. The need for an MRI examination for this particular patient was confi rmed by the referring physician, radiologists and anaesthesiology team at our institution. The pacemaker identifi cation card was examined in order to acquire information about the type of device and attached leads. The presence of any abandoned leads, extenders or adaptors, lead remnants or fractured leads was not identifi ed. The MRI conditionality status was determined using the device identifi cation card and the manufacturer’s technical manual. The latter was acquired using the Magresource database. The combination of the device (Entovis non-US) and pacemaker leads (Solia S53) was identifi ed as MRI conditional under specifi c conditions that include the use of an exclusion zone. On the examination day, the patient was fi rst appointed to the pacemaker clinic where the anaesthesiology team interrogated the functionality of the device and patient device dependency. They discovered that the patient is not pacemaker dependant and in accordance with this, the CIED system was reprogrammed to the asynchronous mode DOO. Device parameters, capture threshold, lead impedance, sensing amplitude and battery status were measured. Measurements were in the normal range for all parameters. After the device interrogation and reprogramming, the patient was appointed to the MRI department where we performed the standard MR safety screening process. MRI scanner conditions were adjusted according to the Biotronik ProMRI technical manual. The technical manual allows the use of a clinical MRI scanner with a closed bore and a static magnetic Figure 3: Combinations of device types and pacemaker leads that require an exclusion zone at 1.5T according to the Biotronik ProMRI technical manual. Figure 4: Defi ned isocenter levels and exclusion zones for CIED. 20 Medical Imaging and Radiotherapy Journal (MIRTJ) 38 (2) Godec M. et al./ MRI safety and management of patients with cardiovascular implantable electronic device ... fi eld strength of 1.5T for this particular device. The maximum slew rate of the gradient fi elds was limited to 200T/m/s and the mean specifi c absorption rate did not exceed 2W/kg. For this combination of the pacemaker model and attached leads, the permissible positioning zone must always be maintained for the duration of the MRI scan. In accordance with the manufacturer’s technical manual, we adjusted the isocenter of the high frequency coil to the level of the greater trochanter as presented in Figure 4. Patient monitoring was performed and maintained by the anaesthesiology team for the duration of the MRI examination. We used continuous real-time ECG monitoring and pulse oximetry consulting the technical manual and recommendations for the management of patients with implanted MR conditional devices presented in this paper. ECG monitoring was performed with the Invivo MRI Patient Monitoring System, Model 865214 that is compatible with the strong magnetic fi elds in the MRI environment. Monitoring was continued until the patient was removed from the MRI Scanner. The patient was appointed back to the pacemaker clinic where the anaesthesiology team reprogrammed the device to its original settings and interrogated the functionality of the device and possible changes in device parameters. No changes of device parameters were discovered. The MRI examination of the patient was completed without complications; therefore, no adverse eff ects were reported. MRI images were without artefacts. CONCLUSION In the past decades, cardiovascular implantable electronic devices shifted from being a complete contraindication in the MRI environment to not presenting a signifi cant risk for MR conditional devices in controlled situations. This step forward was enabled by the advances in engineering to limit interactions between the device and MRI magnetic fi elds. Interactions were minimized with the use of optimised imaging and screening protocols for patients with a CIED undergoing MRI examinations. Recent clinical studies and published guidelines suggest that MRI of patients with either MRI conditional or non-MRI-conditional CIED devices are relatively safe under specifi c conditions. Multidisciplinary pre- procedure planning, strict screening process, monitoring and device evaluation protocols are of key importance for ensuring safe MR imaging in patients with a CIED. Multidisciplinary management requires cooperation between the referring physician, radiologist, radiographer and the cardiac electrophysiology team. The screening process and device evaluation protocols must determine the MRI conditionality of the device and patient device dependency status. Based on this information, appropriate device reprogramming should be performed. The MRI protocol for imaging MRI conditional CIED devices must be in compliance with manufacturer’s technical manual recommendations. Some device models require the use of exclusion zones denoting that the isocenter of the high frequency coil must not be placed over this anatomic area (usually the thorax region). Recommendations for imaging MR non-conditional CIED devices include the limitation of a static magnetic fi eld to 1.5T, limitation of the maximum gradient fi eld slew rate to ≤ 200T/m/s and use of the Normal Operating Mode for specifi c absorption rate (<2W/ kg). Patient monitoring must be performed using continuous real-time ECG and pulse oximetry. It is recommended that ECG and pulse oximetry monitoring is continued until clinically appropriate CIED settings are restored. REFERENCES 1. Bauer Rudolf W, Lau D, Wollmann C, McGavigan A, Mansourati J, Reiter T, et al. Clinical safety of ProMRI implantable cardioverter-defi brillator systems during head and lower lumbar magnetic resonance imaging at 1.5 Tesla. Sci Rep. [Internet] 2019 [cited 2022 Feb 25]; 9:1-11. Available from: https://www.nature.com/articles/ s41598-019-54342-4 DOI: 10.1038/s41598-019-54342-4 2. Vigen K, Reeder S, Hood M, Steckner M, Leiner T, Dombroski D, et al. Recommendations for Imaging Patients With Cardiac Implantable Electronic Devices (CIEDs). JMRI. 2020; 52: 1311-17. 3. Verma N, Knight B. Update in Cardiac Pacing. Arrhythm Electrophysiol Rev. [Internet] 2019 [cited 2022 Feb 24]; 8(3): 228-33. Available from: https:// www.ncbi.nlm.nih.gov/pmc/articles/PMC6702597/ DOI: 10.15420/aer.2019.15.3 4. Abi-Samra F. Cardiac Implantable Electrical Devices: Bioethics and Management Issues Near the End of Life. Ochsner J. 2011; 11(4): 342-47. 5. Wilkoff B, Cantillon D. Device Therapy in Heart Failure. In: Mann D, editors. Heart Failure: A Companion to Braunwald’s Heart Disease. 2nd ed. Philadelphia: Saunders; 2011. p. 694-793. 6. Blessberger H, Kiblboeck D, Reiter C, Lambert T, Kellermair J, Schmit P, et al. Monocenter Investigation Micra MRI study (MIMICRY): feasibility study of the magnetic resonance imaging compatibility of a leadless pacemaker system. EP Europace. 2018; 21(1): 137-41. 7. Groner A, Grippe K. The leadless pacemaker: An innovative design to enhance pacemaking capabilities. JAAPA 2019;32:48-50. 8. Schaller R, Brunker T, Riley M, Marchlinski F, Nazarian S, Litt H. Magnetic Resonance Imaging in Patients With Cardiac Implantable Electronic Devices With Abandoned Leads. JAMA Cardiol. 2021; 6(5): 549-56. 9. Deshpande S, Kella D, Padmanabhan. MRI in patients with cardiac implantable electronic devices: A comprehensive review. Pacing Clin Electrophysiol. 2020; 44(2): 360-72. 10. Martinez J, Ennis D. MRI of Patients with Cardiac Implantable Electronic Devices. Curr Cardiovasc Imaging Rep. 2019; 12(27): 1-9. 11. Shinbane J, Colleti P, Shellock F. Magnetic resonance imaging in patients with cardiac pacemakers: era of “MR Conditional” designs. J Cardiovasc Magn Reson. 2011; 13(63): 1-13. Medical Imaging and Radiotherapy Journal (MIRTJ) 38 (2) 21 Godec M. et al./ MRI safety and management of patients with cardiovascular implantable electronic device ... 12. Santini L, Forleo G, Santini M. Implantable devices in the electromagnetic environment. J Arrhythm. 2013; 29(6): 325-33. 13. Kalb B, Indik J, Ott P, Martin D. MRI of patients with implanted cardiac devices. J Magn Reson Imaging. 2017; 47(3): 595-603. 14. Munawar D, Chan J, Emami M, Kadhim K, Khokhar K, O’Shea C, et al. Magnetic resonance imaging in non- conditional pacemakers and implantable cardioverter- defi brillators: a systematic review and meta-analysis. Europace. 2020; 22(2): 288-98. 15. Muthalaly R, Nerlekar N, Ge Y, Kwong R, Nasis A. MRI in Patients with Cardiac Implantable Electronic Devices. Radiology. 2018; 289(2): 281-92. 16. Stühlinger M, Burri H, Vernooy K, Garcia R, Lenarczyk R, Sultan A, et al. EHRA consensus on prevention and management of interference due to medical procedures in patients with cardiac implantable electronic devices. Europace. 2022. 17. Yang E, Suzuki M, Nazarian S, Helperin H. Magnetic resonance imaging safety in patients with cardiac implantable electronic devices. Trends Cardiovasc. Med. 2021; 7(4): 1-7. 18. Mason S, Osborn J, Dhar R, Tonkin A, Ethington J, Benuzillo J, et al. Real world MRI experience with nonconditional and conditional cardiac rhythm devices after MagnaSafe. J Cardiovasc Electrophysiol. 2017; 28(12): 1468-74. 19. Russo R, Costa H, Silva P, Anderson J, Arshad A, Biederman R, et al. Assessing the Risks Associated with MRI in Patients with a Pacemaker or Defi brillator. N Engl J Med. 2017; 376: 755-64. 20. Dahiya G, Wetzel A, Kyvernitakis A, Gevenosky L, Williams R, Shah M, et al. Impact of magnetic resonance imaging on functional integrity of non-conditional cardiovascular implantable electronic devices. Pacing Clin Electrophysiol. [Internet] 2021 [cited 2022 Feb 25]; 44(8):1312-19. Available from: https://onlinelibrary-wiley-com.nukweb. nuk.uni-lj.si/doi/full/10.1111/pace.14298 DOI: 10.1111/ pace.14298. 21. Camacho J, Moreno Coursey C, Shah A, Mittal P, Mengistu A, Lloyd M, et al. Safety and Quality of 1.5-T MRI in Patients with Conventional and MRI-Conditional Cardiac Implantable Electronic Devices After Implementation of a Standardized Protocol. Am J Roentgenol. 2016; 207(3): 599-604. 22. Yadava M, Nugent M, Krebsbach A, Minnier J, Jessel P, Henrikson C. Magnetic resonance imaging in patients with cardiac implantable electronic devices: a single- center prospective study. J Interv Card Electrophysiol. 2017; 50: 95-104. 23. Strom J, Whelan J, Shen C, Zheng S, Mortele K, Kramer D, et al. Safety and utility of magnetic resonance imaging in patients with cardiac implantable electronic devices. Heart Rhythm. 2017; 14(8): 1138-44. 24. Horwood l, Attili A, Luba F, Ibrahim E, Parmar H, Stojanovska J, et al. Magnetic resonance imaging in patients with cardiac implanted electronic devices: focus on contraindications to magnetic resonance imaging protocols. Europace. 2017; 19(5): 812-17. 25. Maass A, Hemels M, Allaart C. Magnetic resonance imaging in patients with cardiac implantable electronic devices. Neth Heart J, 2018; 26: 584-90. 26. Seewöster T, Löbe S, Hilbert S, Bollmann A, Sommer P, Lindemann F, et al. Cardiovascular magnetic resonance imaging in patients with cardiac implantable electronic devices: best practice and real-world experience. Europace. 2019; 21(8): 1220-28. 27. Nyotowidjojo I, Skinner K, Shah A, Bisla J, Singh S, Khoubyari R, et al. Thoracic versus nonthoracic MR imaging for patients with an MR nonconditional cardiac implantable electronic device. Pacing Clin Electrophysiol. 2018; 41(6): 589-96. 28. Dandamudi S, Collins J, Carr J, Lin A, Passman R, Knight B, et al. The Safety of Cardiac and Thoracic Magnetic Resonance Imaging in Patients with Cardiac Implantable Electronic Devices. Acad Radiol. 2016; 23(12): 1498-1505. 29. Indik J, Gimbel R, Abe H, Verma A, Wilkoff B, Woodard P, et al. 2017 HRS expert consensus statement on magnetic resonance imaging and radiation exposure in patients with cardiovascular implantable electronic devices. Heart Rhythm. 2017; 14(7): 97-117. 30. Poh Ghim P, Liew C, Yeo C, Chong Roy L, Tan A, Poh A. Cardiovascular implantable electronic devices: a review of the dangers and diffi culties in MR scanning and attempts to improve safety. Insights Imaging. [Internet]. 2017 [cited 2022 Feb 24]; 8(4): 405-18. Available from: https:// www.ncbi.nlm.nih.gov/pmc/articles/PMC5519496/ DOI: 10.1007/s13244-017-0556-3 31. Korutz A, Obajuluwa A, Lester M, McComb E, Hijaz T, Collins J, et al. Pacemakers in MRI for the Neuroradiologist. AJNR Am J Neuroradiol. 2017; 38(12): 2222-30. 22 Medical Imaging and Radiotherapy Journal (MIRTJ) 38 (2) Medical Imaging and Radiotherapy Journal (MIRTJ) 38 (1) Review article DIAGNOSTIC REFERENCE LEVELS IN DENTAL RADIOLOGY: A SYSTEMATIC REVIEW Diagnostične referenčne ravni v dentalni radiologiji - Sistematični pregled literature Alenka MATJAŠIČ University of Ljubljana, Faculty of health sciences, Medical imaging and radiotherapy department, Zdravstvena pot 5, 1000 Ljubljana, Slovenia * Corresponding author: alenka.matjasic@zf.uni-lj.si Received: 20. 8. 2021 Accepted: 9. 2. 2022 https://doi.org/10.47724/MIRTJ.2021.i02.a003 ABSTRACT Purpose: The purpose of this work was to review published articles in the fi eld of diagnostic reference levels in dental radiology, and to determine which areas have not been covered yet and require further scientifi c studies. The aim was also to determine if there are any dose optimization procedures suggested after DRL establishment. Materials and methods: A systematic review was performed using the Science Direct, PubMed, CINAHL (via EBSCOhost) and Dentistry & Oral Sciences Source (via EBSCOhost) databases, following the Cochrane Network study design guidelines. Articles were analysed and presented by author, year of publication, country of origin, technology (e.g. digital radiography, computed radiography and fi lm-screen), radiographic type (e.g. intraoral, panoramic and CBCT), units of measurement and main conclusions for each study. Results: Thirteen scientifi c articles on dose reference values in dental radiology were evaluated. Full-access articles published between 2001 and 2021 were used, and both reviews and original research articles were included. The studies address the defi nition or analysis of DRLs in intraoral and panoramic dental imaging and in dental CBCT imaging. Many studies report results based on diff erent image-receiving systems (e.g. DR, CR and fi lm-screen). The fi lm-screen system yielded the highest dose values of all three systems. All studies reviewed describe DRLs for the adult population, while only four also describe paediatric DRLs. Conclusion: Most EU countries have not yet set national DRLs for dental radiology. Most studies set or revise DRLs at the national level and compare them with guidelines from literature and from similar studies conducted in other countries. Most of these studies observed DRLs in the adult population. DRLs should also be set in the fi eld of dental CBCT imaging, as the use of this technology is rapidly increasing and the dose levels are incomparably higher than in general dental radiography. Keywords: dental radiography, diagnostic reference levels, intraoral imaging, panoramic dental imaging. IZVLEČEK Namen: Namen tega dela je pregledati objavljene članke s področja diagnostičnih referenčnih ravni v dentalni radiologiji, določiti področja znotraj slednje, ki še niso bila obravnavana in ki zahtevajo nadaljnje raziskave, pa tudi raziskati, ali po vzpostavitvi diagnostičnih referenčnih ravni študije predlagajo katero od oblik optimizacije doze. Materiali in metode: Izvedli smo sistematični pregled literature z uporabo podatkovnih baz Science Direct, PubMed, CINAHL (preko EBSCOhost) ter Dentistry & Oral Sciences (preko EBSCOhost). Pri zasnovi študije smo delno sledili smernicam Cochrane omrežja. Članke smo analizirali in razvrstili glede na avtorje, leto objave, državo nastanka, tehnologijo (digitalna radiografi ja, računalniška radiografi ja, sistem folija-fi lm), vrsto slikanja (intraoralno, panoramsko, CBCT) in uporabljene merske enote, za vsako študijo pa smo zapisali glavne ugotovitve.  Rezultati: Trinajst znanstvenih člankov, ki obravnavajo diagnostične referenčne ravni v dentalni radiolografi ji, smo analizirali in ocenili. Uporabili smo članke s polnim dostopom, objavljene med leti 2001 in 2021. Upoštevali smo tako izvirne kot pregledne znanstvene članke. Raziskave obravnavajo vzpostavitev ali analizo DRR-jev pri intraoralnem, panoramskem in zobnem CBCT slikanju. Velik delež raziskav poroča in ločuje rezultate glede na slikovni sprejemnik (DR, CR, folija-fi lm). Sistem folija-fi lm se je izkazal kot sistem z najvišjimi doznimi vrednostmi. Vse analizirane raziskave obravnavajo odraslo populacijo, le 4 opisujejo tudi DRR-je za pediatrijo.   Zaključek: Večina držav Evropske unije še nima vzpostavljenih DRR-jev na nacionalnih ravneh za področje dentalne radiologije. Večina obravnavanih raziskav vzpostavlja DRR-je na nacionalni ravni in jih primerja s smernicami iz literature ali s podobnimi študijami, izvedenimi v drugih državah. Večina raziskav obravnava odrasle paciente. Pojavlja se pomanjkanje raziskav s področja DRR-jev za dentalno CBCT slikanje, saj je uporaba te tehnologije v strmem porastu, dozne ravni zanjo pa so občutno višje v primerjavi s splošno dentalno radiologijo.  Ključne besede: dentalna radiografi ja, diagnostične referenčne ravni, intraoralno slikanje, panoramsko slikanje Medical Imaging and Radiotherapy Journal (MIRTJ) 38 (2) 23 Matjašič A. / Diagnostic reference levels in dental radiology: a systematic review Introduction Technological development in dental radiology began after 1919, when adequate electrical insulation made it possible to safely perform intraoral imaging techniques. Panoramic dental imaging was developed and introduced for general use in the 1960s, while computed tomography has been used since the 1970s (1). The newest technology in dental radiology is cone beam computed tomography (CBCT), the use of which is rapidly increasing. It was developed for the maxillofacial region in 1995 and has been available for commercial use since 1999. Its use is popular primarily because it is a low-cost diagnostic technology that enables treatment planning and image- guided surgical and operative procedures (2). Ionizing radiation exposure in dental radiology contributes to approximately 2.5% of the eff ective dose received during medical examinations. The average adult eff ective dose for intraoral radiographs is 0.005 mSv for panoramic radiographs 0.01 mSv, and 0.011 to 1.073 mSv for dental computed tomography (3). According to the European guidelines for radiation protection in dental radiology, 96 to 449 dental radiological examinations are performed per 1,000 inhabitants in the countries of the European Union that have provided such data (4). Because of the large number of professionals performing such procedures and because many examinations in dentistry involve the use of ionizing radiation, certain radiation protection measures must be considered for patients exposed to a certain dose of ionizing radiation during these imaging examinations. One way to ensure optimal performance by a healthcare provider when using ionizing radiation is to determine diagnostic reference levels (DRLs) DRLs are usually easy to measure and are directly related to the radiation dose received by the patient (5). DRLs are the dose levels for ionizing radiation in diagnostic radiologic procedures that should not be exceeded if the procedure is optimized. They are determined using measured dose levels for patients undergoing a specifi c diagnostic examination. It is recommended that they be measured on as many x-ray machines as possible. The DRL is determined by the value of the third quartile of all doses received (6). Diagnostic reference values for radiological procedures in adults have been established for 72% of the 36 European countries. According to the European Commission report, the specifi c DRL values for dental radiology have only been applied at the national level in Finland and France (7). The European guidelines for radiation protection in dental radiology also state that few countries have conducted national or similar studies to determine DRLs and that there are no published DRLs for dental radiography at the European level (4). The establishment of national and local DRLs is proposed by the International Atomic Energy Agency for all medical examinations and procedures, for all clinical indications and for all patient groups (adults and size-dependent groups of children) (8). Because of the aforementioned large number of radiologic procedures performed annually in dentistry, the establishment of DRLs for this profession is of great importance. Specifi cally, for CBCT imaging, there is also a great need to establish DRLs, as the doses of ionizing radiation received in this technology are considerably higher than those received in intraoral or panoramic dental imaging and are comparable to those received by the patient during radiographs of the pelvis or abdomen (7). We use diff erent units of measurement to determine DRL values. In general radiography, air kerma product (KAP or PKA) and entrance surface air kerma (Ke) are commonly used. CTDIvol (computed tomography dose index) or dose length product (DLP) are used in computed tomography, while the received dose is considered in terms of activity delivered to the patient or activity per kilogram of body weight in nuclear medicine. Literature recommends using incident air kerma (Ki) for intraoral dental imaging and PKA for dental panoramic imaging (8). The authors of the articles discussed in this paper also use the unit PED (patient entrance dose) instead of ESD (entrance skin/surface dose). It is defi ned as the absorbed dose in air measured at the end of the spacer 'cone' for typical examinations without backscatter from the patient (9). Aim of the study The aim of this systematic review was to investigate how many countries, health facilities or radiology departments have already established diagnostic reference values for dental radiology. The aim was also to determine which areas of dental radiology (intraoral, panoramic or CBCT imaging) these DRLs cover and whether their establishment has suggested dose optimization for patients. Methods We performed a systematic review of literature. We relied in part on the guidelines of the Cochrane network when designing our study (10). Sources The Science Direct, PubMed in CINAHL (via EBSCOhost) and Dentistry & Oral Sciences Source (via EBSCOhost) scientifi c databases (11–14) were used to perform the search via the University of Ljubljana's and Central Medical Library's remote access. Inclusion and exclusion criteria A search algorithm based on a combination of keywords and logical operators was used in this review and is described in Table 1. No exclusion criteria in the fi rst search (for example the use of logical operator NOT) were applied. In the next step of the process, other conditions were set: full access articles, not older than 10 years (published between 2001 and 2021), and the inclusion of reviews as well as original research articles. After the initial search, which yielded 134 documents, exclusion criteria were applied and, at the end of the process, 13 articles were considered for inclusion in this review. The step-by-step process of document selection is shown in Figure 1. The results of the review were then presented in Table 2. Studies were listed by author, year of publication, country of origin, technology (e.g. digital radiography, computed 24 Medical Imaging and Radiotherapy Journal (MIRTJ) 38 (2) Matjašič A. / Diagnostic reference levels in dental radiology: a systematic review radiography and fi lm-screen), type of radiography (e.g. intraoral, panoramic and CBCT), units of measurement, and main conclusions for each study. Results By using search terms and exclusion criteria described earlier and after further analysis of titles and abstracts, 13 studies were eligible for inclusion in this systematic review and are presented in Table 2. This systematic review analysed 13 scientifi c articles from 10 diff erent countries that address the area of diagnostic reference values in dental radiology. Most of them deal with the establishment and/or analysis of DRLs in general radiography (intraoral and panoramic dental imaging), while only two studies deal with CBCT imaging (17, 21). The DRLs are considered at the national level, while the authors performed comparisons between institutions and a larger number of radiographic units. Only Izawa et al (20) specify local DRLs and a comparison of three units at an institution with the aim of optimising and standardising the institution's imaging protocols. The authors of studies also frequently reported results on diff erent image-receiving systems (e.g. DR, CR and fi lm- screen). In all studies that made such a comparison, the fi lm- screen system was found to have the highest dose levels of all three systems. All studies reviewed describe DRL values for the adult population, while only four studies (9, 19, 22, 25) also describe paediatric DRL values. The importance of the latter is particularly emphasised in Holroyd's study, as it describes cephalometric imaging and the associated dose burden. Since cephalometric imaging is most commonly used in orthodontics and the patients are mostly children, special attention should be paid to optimal (as low as possible) dose exposure in this type of dental radiology, since children are more sensitive to ionising radiation, which can cause more damage in children than in adults (19). Discussion All articles studied report specifi c DRL values, i.e. the value of the 3rd quartile of measured doses from their data. The values are then compared with literature, with guidelines or, as in the study by Manousaridis et al. (23), with previous studies from the same country. This shows the importance of national DRL facilities everywhere, including Slovenia. Some authors emphasise the legal reasons for conducting these types of studies. For example, Alcaraz et al (15) mention the legal status of mandatory annual DRL reviews as part of the quality assurance programme in Spain. This may serve as a reason for conducting such studies. These reviews are mandatory in most European countries, but not all countries specify the time frame for their implementation. For example, Slovenian legislation does not specify how often a DRL review should be performed, but does states that the institution responsible for radiation protection should set DRL values based on systematic reviews of patient exposure and that it should follow European and other international recommendations in this area (27). Considering the small number of studies performed in CBCT imaging DRLs, this area of radiology seems very suitable for further research. The use of this technology is rapidly increasing, but dose levels can be up to 26 times higher than in dental panoramic imaging (18). Dose optimization for specifi c imaging modalities should always be considered. This applies to exposure parameters for general radiography, as well as FOV and resolution (these two can be controlled by the user) for CBCT imaging. It is especially important to establish and regularly revise DRLs, as they are one of the key factors that guide all parties involved in the process (dentists, radiographers, radiologists, medical physicists and service technicians) toward a high-quality work process that causes the least possible harm to patients. Limitations The fact that there are signifi cantly fewer studies in the fi eld of dental radiology compared to general radiography (X-ray or computed tomography) is the reason why this systematic review has limitations. When the sample is larger, the results are easier to interpret. In our case, we can only compare them in terms of their main results and derive some guidelines for possible further research, for example, the recommendation to extend the research to the fi eld of CBCT imaging and the associated dose burden. Another problem that appears in our review is the problem of comparing the studies correctly because they do not all use the same units of measurement. Some even suggest the use of new units of measurement, although literature recommends using Ki for intraoral and PKA for panoramic images. Table 1: Keywords and logical operators 1st keyword Logical operator 2nd keyword Logical operator 3rd keyword dental OR dentistry OR oral Logical operator: AND x- ray OR radiology OR radiography Logical operator: AND DRL OR diagnostic reference levels Medical Imaging and Radiotherapy Journal (MIRTJ) 38 (2) 25 Ta bl e 2: R ev ie w o f s tu di es A ut ho r Ye ar Co un tr y Sa m pl e Te ch no lo gy Ra di og ra ph y ty pe U ni ts o f m ea su re m en t M ai n co nc lu si on s A lc ar az e t a l. (1 5) 20 12 Sp ai n 16 17 5 offi c ia l re po rt s, ga th er ed be tw ee n 20 02 an d 20 09 D R, C R, fi l m -s cr ee n In tr ao ra l ES D Ei gh t- ye ar -lo ng o bs er va tio n (2 00 2– 20 09 ). D RL v al ue in 2 00 9 w as 3. 1 m G y (w hi ch is 3 5. 4 % le ss th an in 2 00 2 w he n th e va lu e w as 4 .8 m G y) . E U g ui de lin es fo r i nt ra or al im ag in g in 2 00 4 re co m m en de d a va lu e of 4 m G y; 8 3. 4 % o f i ns tit ut io ns a re b el ow th is v al ue . D RL va lu es a ls o ch an ge w hi ch e ac h sy st em u se d (D R ha s th e lo w es t, w hi le fi lm -s cr ee n ha s th e hi gh es t o ne ). Re gu la r r ev is io ns a re su gg es te d, a t l ea st e ve ry th re e ye ar s (S pa ni sh le gi sl at io n ev en re qu ire s th em e ve ry y ea r) a s pa rt o f t he Q A p ro gr am m e in d en ta l offi c es . L im ita tio n: th er e is n o da ta o n ho w m an y ex po si tio ns w er e re pe at ed . A lc ar az e t a l. (1 6) 20 15 Sp ai n 34 14 3 offi c ia l re po rt s ga th er ed be tw ee n 19 97 an d 20 14 D R, C R, fi l m -s cr ee n In tr ao ra l ES D D RR o bs er va tio n fr om 2 00 2– 20 14 . I n 20 14 , t he v al ue w as 2 .8 m G y (4 1. 7 % le ss th an in 2 00 2 w he n th e va lu e w as 4 .8 m G y) . I n th e la st th re e ye ar s si nc e th ei r l as t s tu dy , D RL v al ue s st ab ili se d. It is a ss um ed th at th is h ap pe ne d be ca us e of th e st ab ili sa tio n in te ch no lo gy s ys te m c ha ng es a nd th e es ta bl is hm en t o f d ig ita l sy st em s. Fo r e ve ry x -r ay m ac hi ne , 1 0 ex po su re s w er e m ad e, m ea su re d in m G y, fo r u pp er s ec on d m ol ar . Ch ris to fi d es et a l. (9 ) 20 16 Cy pr us 20 m ac hi ne s Fi lm -s cr ee n In tr ao ra l D A P Th ey s tr es s th e im po rt an ce o f D RL e st ab lis hm en t f or a ll ag e gr ou ps (t hi s st ud y al so in cl ud ed c hi ld re n) a nd th e ca lc ul at io n of P ED v al ue . D RL s ar e be tw ee n 7. 23 m G y (u pp er m ol ar , a du lts ) a nd 1 .8 8 m G y (lo w er in ci so r, ch ild re n) . T he D RL s ar e sl ig ht ly h ig he r t ha n th os e of EU g ui de lin es , a lth ou gh th os e ar e ex pr es se d as E SD v al ue s, w hi le th e on es fr om th is s tu dy a re in P ED v al ue , w hi ch d oe s no t i nc lu de ba ck sc at te r r ad ia tio n. Th er e ar e si gn ifi ca nt d iff er en ce s be tw ee n th e 20 lo ca tio ns (x -r ay m ac hi ne s) . D os e va lu e st an da rd is at io n an d re du ct io n ar e su pp os ed to b e ac hi ev ed in th e fu tu re , p rim ar ily b y tr an si tio ni ng to di gi ta l r ec ei ve rs . D el eu e t a l. (1 7) 20 20 Sw itz er la nd 22 7 m ac hi ne s D R CB C T P K A , C TD I vo l Be si de s D RL e st ab lis hm en t, th e st ud y al so s ug ge st s th e es ta bl is hm en t o f c er ta in g ui de lin es a nd re co m m en da tio ns o n FO V (fi el d of v ie w ) s iz es , e ve n th ou gh th ei r r es ul ts s ho w ed th at m os tly sm al l s iz e FO V ar e us ed (a ve ra ge a re a 25 c m 2 , w hi ch m ea ns th is as pe ct o f d os e re du ct io n is a lre ad y co ns id er ed a nd in u se ). Th e su gg es te d D RL s in th is s tu dy a re n or m al iz ed to th e FO V di m en si on . H ea d an d ne ck C BC Ts w er e al so c on si de re d in th is s tu dy , n ot o nl y de nt al , a lth ou gh th e in di ca tio ns s til l m os tly re qu ire d en ta l C BC Ts , so th e es ta bl is hm en t o f D RL s in th is a re a is e sp ec ia lly im po rt an t. Matjašič A. / Diagnostic reference levels in dental radiology: a systematic review 26 Medical Imaging and Radiotherapy Journal (MIRTJ) 38 (2) A ut ho r Ye ar Co un tr y Sa m pl e Te ch no lo gy Ra di og ra ph y ty pe U ni ts o f m ea su re m en t M ai n co nc lu si on s H an e t a l. (1 8) 20 11 So ut h Ko re a 12 9 m ac hi ne s D R In tr ao ra l, pa no ra m ic , ce ph al om et ric , CB C T D A P Th e m ea su re d va lu es fo r i nt ra or al e xa m in at io ns a re 5 5. 5; 4 6 an d 36 .5 m G y* cm 2 ( fo r u pp er m ol ar , p re m ol ar a nd in ci so r, re sp ec tiv el y) an d 12 0. 3; 1 46 a nd 3 ,2 03 m G y* cm 2 f or e xt ra or al e xa m in at io ns (fo r p an or am ic , c ep ha lo m et ric a nd C BC T im ag in g, re sp ec tiv el y) . In in tr ao ra l d en ta l i m ag in g, th e D A P va lu e re la te s to tu be c ur re nt an d ex po su re ti m e pr od uc t ( m A s) , w hi le th e CB C T im ag in g’ s D A P is m or e cl os el y lin ke d to th e FO V. T he re a re s om e di ff e re nc es in th e m ea su re d do se v al ue s be tw ee n pr iv at e cl in ic s an d un iv er si ty ho sp ita ls . H ol ro yd e t a l. (1 9) 20 11 G re at B rit ai n 42 m ac hi ne s D R, C R, fi l m -s cr ee n Ce ph al om et ric D A P A p ha nt om s tu dy . D A P va lu es fo r a du lts : 4 0 m G y* cm 2 f or d ig ita l sy st em s an d 42 m G y* cm 2 f or s cr ee n- fi l m . F or c hi ld re n: 2 5 m G y* cm 2 . Iz aw a et a l. (2 0) 20 17 Ja pa n 3 m ac hi ne s (lo ca l D RL s) Fi lm -s cr ee n In tr ao ra l P K A , P ED Lo ca l D RL s w er e es ta bl is he d ta ki ng in to a cc ou nt a p os si bl e di ff e re nc e be tw ee n ge nd er s. Th e do se v al ue s ar e sl ig ht ly lo w er in w om en , w hi ch is s up po se d to b e a co ns eq ue nc e of th e di ff e re nc e in s iz e, s in ce w om en a e us ua lly s m al le r, so th e op er at or s ho ul d ad ju st e xp os ur e pa ra m et er s. PE D v al ue s ar e 1. 56 ± 0 .2 7, 1 .0 9 ± 0. 31 , 1 .9 2 ± 0. 38 , m G y fo r u pp er in ci so rs , p re m ol ar s an d m ol ar s, re sp ec tiv el y, a nd 1 .2 7 ± 0. 22 , 2 .4 2 ± 0. 33 in 1 .5 9 ± 0. 20 m G y fo r lo w er in ci so rs , p re m ol ar s an d m ol ar s, re sp ec tiv el y. Ki m e t a l. (2 1) 20 12 So ut h Ko re a 12 6 (1 04 co ns id er ed in th e st ud y) m ac hi ne s D R, C R, fi l m -s cr ee n in tr ao ra l D A P, PE D Th e st ud y re co m m en ds D RL v al ue s fo r S ou th K or ea : 3 .1 m G y (P ED ) an d 87 .4 m G y* cm 2 ( D A P) fo r l ow er m ol ar fo r a du lts . T hi s st ud y al so sh ow s lo w er d os e va lu es in d ig ita l s ys te m s co m pa re d to th os e in fi l m -s cr ee n sy st em s. Th ey a ls o co ns id er ed th e in st al la tio n du ra tio n of th e m ac hi ne (< 5 ye ar s in > 6 ye ar s) a nd th e ty pe o f d en ta l x -r ay m ac hi ne (e .g . w al l-m ou nt ed fi xe d ty pe a nd h an d- he ld p or ta bl e ty pe ). Th er e w er e no s ta tis tic al ly s ig ni fi c an t d iff er en ce s w ith re sp ec t t o eq ui pm en t i ns ta lla tio n du ra tio n an d ty pe o f d en ta l X -r ay sy st em . M an ou sa rid is et a l.( 22 ) 20 15 G re ec e 51 9 m ac hi ne s D R, C R fi l m -s cr ee n pa no ra m ic K i Th re e ca te go rie s w er e an al ys ed : c hi ld re n, p et ite a du lts a nd av er ag e ad ul ts . R ec om m en de d D RL s w er e 2. 2; 3 .3 a nd 4 .1 m G y, re sp ec tiv el y. T hr ee s ys te m s w er e co m pa re d as w el l ( D R, C R an d fi l m -s cr ee n) , w ith d os e va lu es a t t he 3 rd q ua rt ile o f 3 .5 ; 4 .2 a nd 3. 7 m G y, re sp ec tiv el y. A s w e ca n se e, th e hi gh es t d os e va lu e is re co rd ed w ith th e CR s ys te m . Matjašič A. / Diagnostic reference levels in dental radiology: a systematic review Medical Imaging and Radiotherapy Journal (MIRTJ) 38 (2) 27 A ut ho r Ye ar Co un tr y Sa m pl e Te ch no lo gy Ra di og ra ph y ty pe U ni ts o f m ea su re m en t M ai n co nc lu si on s M an ou sa rid is et a l. (2 3) 20 13 G re ec e 52 9 m ac hi ne s D R, C R, fi l m -s cr ee n In tr ao ra l K i D RL v al ue fo r u pp er m ol ar is s et a t 0 .9 5 m G y fo r d ig ita l s ys te m s an d 2. 90 m G y fo r fi lm -s cr ee n, w hi ch is c om pa ra bl e to o r e ve n lo w er th an in th os e co un tr ie s th at a t t he ti m e of th is s tu dy p ro vi de d su ch da ta (S pa in , U SA , R om an ia , G re at B rit ai n an d pr ev io us s tu di es in G re ec e) . Pr as ka lo e t a l. (2 4) 20 20 Bo sn ia a nd H er ze go vi na 41 m ac hi ne s D R, fi l m -s cr ee n In tr ao ra l K i , P KA N ew D RL s fo r t he fi lm -s cr ee n sy st em (3 .5 m G y) a nd fo r d ig ita l re ce iv er s (1 .2 m G y) a re re co m m en de d an d ar e si gn ifi ca nt ly lo w er th an th os e es ta bl is he d un til n ow a t t he n at io na l l ev el w ith a D RL v al ue o f 7 m G y. T hi s va lu e w as ta ke n fr om li te ra tu re a nd n ot es ta bl is he d as a re su lt of a n at io na l s tu dy . T he re a re c on si de ra bl y lo w er d os es fo r d ig ita l r ec ei ve rs . Su lim an , A bd el ga di r (2 5) 20 18 Su da n 14 m ac hi ne s D R, fi l m -s cr ee n In tr ao ra l, pa no ra m ic K i , P KA Th e st ud y re co m m en ds n ew D RL s fo r i nt ra or al im ag in g: 1 .4 5 m G y (D R) , 4 .4 5 m G y (fi lm -s cr ee n) a nd 3 .0 1 m G y (c om bi ne d) . Fo r p an or am ic d en ta l i m ag in g, o nl y av er ag e va lu es a re s ta te d (a nd n ot th e 3r d qu ar til e, w hi ch is s pe ci fi c fo r D RL s) : 7 0. 4 m G y* cm 2 fo r c hi ld re n an d 10 3. 4 m G y* cm 2 f or a du lts . T he s tu dy d es cr ib es si gn ifi ca nt d iff er en ce s be tw ee n ho sp ita ls . T hi s sh ow s th e th er e is a lo t o f r oo m fo r p ro to co l o pt im is at io n. W al ke r e t a l. (2 6) 20 10 Ire la nd 83 m ac hi ne s da ta un av ai la bl e In tr ao ra l, pa no ra m ic ES D , D W P (d os e w id th pr od uc t) Su gg es te d D RL s fr om th is s tu dy a re 2 .4 m G y fo r l ow er m ol ar fo r in tr ao ra l i m ag in g an d 60 m G y m m fo r p an or am ic im ag in g of ad ul ts . T he s tu dy a ls o re co m m en ds th e in tr od uc tio n of a n ew re fe re nc e qu an tit y 1 m G y/ m A s, w hi ch c on si de rs d os e as w el l a s ex po su re ti m e. T he re co m m en de d D RL fo r i nt ra or al im ag in g w ith th is n ew u ni t i s 1. 03 m G y/ m A s. D RL s ar e co m pa ra bl e to li te ra tu re , so m et im es e ve n lo w er d ue to n ew te ch no lo gi es . Matjašič A. / Diagnostic reference levels in dental radiology: a systematic review 28 Medical Imaging and Radiotherapy Journal (MIRTJ) 38 (2) Conclusion As stated in the introduction from the European Commission Guidelines for Radiation Protection in Dental Radiology, most EU countries have not yet established national DRLs for dental radiology. In this systematic review, 13 original research articles on local or national DRLs in dental radiology for the EU and other countries were discussed. Most of these studies focus on intraoral and panoramic dental imaging, with only a few on CBCT imaging. This implies that there is room for further research in this area. Most studies set or revise DRLs at the national level and compare them with guidelines from literature and from similar studies conducted in other countries. Only one study is the result of local DRL establishment with the goal of protocol optimization. In our selection of articles, DRLs are mostly set for the adult population, and only in four cases for paediatric patients, although they require special consideration in terms of dose optimization. In the future, DRLs should also be set in the fi eld of dental CBCT imaging, as the use of this technology is rapidly increasing, and dose levels are incomparably higher than for general dental radiography. All EU countries should set DRLs for radiographs and for dental CBCT imaging, as suggested in guidelines or recommendations issued by European institutions responsible for radiation protection. References 1. Thomson E, Johnson O. Essentials of Dental Radiography for Dental Assistants and Hygienists. New Yersey: Pearson Education, Inc.; 2012. 2. Scarfe WC, Li Z, Aboelmaaty W, Scott SA, Farman AG. Maxillofacial cone beam computed tomography: Essence, elements and steps to interpretation. Aust Dent J. 2012;57:46–60. 3. American Dental Association. X-rays/Radiographs [Internet]. 2019. Available from: https://www.ada.org/en/ member-center/oral-health-topics/x-rays 4. Commission E. Radiation Protection 136. 2004. 5. European Alara Network. The Diagnostic Reference Levels (DRLs) in Europe. 2007. 6. ZVD Zavod za varstvo pri delu d.d. Določanje obsevanosti pacientov zaradi rentgenskih preiskav v Republiki Sloveniji Poročilo o izvedbi projekta. 2002. 7. Commission E. Diagnostic Reference Levels in Thirty-six European Countries (Part 2/2). 2014;1–73. 8. IAEA. Diagnostic Reference Levels (DRLs) in medical imaging. 9. Christofi des S, Pitri E, Lampaskis M, Papaefstathiou C. Local diagnostic reference levels for intraoral dental radiography in the public hospitals of Cyprus. Phys Medica [Internet]. 2016;32(11):1437–43. Available from: http://dx.doi.org/10.1016/j.ejmp.2016.10.014 10. Higgins J, Thomas J, Chandler J, Cumpston M, Li T, Page M, et al., editors. Cochrane Handbook for Systematic Reviews of Interventions. 2nd ed. 2021. 11. ScienceDirect [Internet]. Available from: https://www. sciencedirect.com/ 12. PubMed [Internet]. Available from: https://pubmed.ncbi. nlm.nih.gov/ 13. EBSCO CINAHL with Full Text [Internet]. Available from: http://web.a.ebscohost.com/ehost/search/ b a s i c ? v i d = 0 & s i d = e 7 b 3 f 3 6 0 - 3 e f c - 4 6 f 7 - 9 8 c 2 - 9ed6fb0330a3%40sessionmgr4006 14. EBSCO Dentistry & Oral Sciences Source [Internet]. Available from: http://cmk-proxy.mf.uni-lj.si:2989/ehost/ search/basic?vid=0&sid=e1627cdd-d2f1-4a9c-bda9- 1ebba86debde%40pdc-v-sessmgr01 15. Alcaraz M, Velasco F, Martínez-Beneyto Y, Alcaraz-Saura M, Velasco E, Achel GD, et al. Evolution of diagnostic reference levels in Spanish intraoral radiology. Radiat Prot Dosimetry. 2012;151(1):166–71. 16. Alcaraz M, Velasco F, Olivares A, Velasco E, Canteras M. Dose reference levels in Spanish intraoral dental radiology: Stabilisation of the incorporation of digital systems in dental clinical practices. Radiat Prot Dosimetry. 2016;172(4):422–7. 17. Deleu M, Dagassan D, Berg I, Bize J, Dula K, Lenoir V, et al. Establishment of national diagnostic reference levels in dental cone beam computed tomography in switzerland. Dentomaxillofacial Radiol. 2020;49(6). 18. Han S, Lee B, Shin G, Choi J, Kim J, Park C, et al. Dose area product measurement for diagnostic reference levels and analysis of patient dose in dental radiography. Radiat Prot Dosimetry. 2012;150(4):523–31. 19. Holroyd JR. National reference doses for dental cephalometric radiography. Br J Radiol. 2011;84(1008):1121–4. 20. Izawa M, Harata Y, Shiba N, Koizumi N, Ozawa T, Takahashi N, et al. Establishment of local diagnostic reference levels for quality control in intraoral radiography. Oral Radiol. 2017;33(1):38–44. 21. Kim EK, Han WJ, Choi JW, Jung YH, Yoon SJ, Lee JS. Diagnostic reference levels in intraoral dental radiography in Korea. Imaging Sci Dent. 2012;42(4):237–42. 22. Manousaridis G, Koukorava C, Hourdakis CJ, Kamenopoulou V, Yakoumakis E, Tsiklakis K. Establishment of diagnostic reference levels for dental panoramic radiography in Greece. Radiat Prot Dosimetry. 2015;165(1–4):111–4. 23. Manousaridis G, Koukorava C, Hourdakis CJ, Kamenopoulou V, Yakoumakis E, Tsiklakis K. Establishment of diagnostic reference levels for dental intraoral radiography. Radiat Prot Dosimetry. 2013;156(4):455–7. Matjašič A. / Diagnostic reference levels in dental radiology: a systematic review Medical Imaging and Radiotherapy Journal (MIRTJ) 38 (2) 29 24. Praskalo J, Beganović A, Milanović J, Stanković K. Intraoral dental x-ray radiography in bosnia and herzegovina: study for revising diagnostic reference level value. Radiat Prot Dosimetry. 2020;190(1):90–9. 25. Suliman II, Abdelgadir AH. Patient radiation doses in intraoral and panoramic X-ray examinations in Sudan. Phys Medica [Internet]. 2018;46(February):148–52. Available from: https://doi.org/10.1016/j.ejmp.2018.01.017 26. Walker C, van der Putten W. Patient dosimetry and a novel approach to establishing Diagnostic Reference Levels in dental radiology. Phys Medica [Internet]. 2012;28(1):7– 12. Available from: http://dx.doi.org/10.1016/j. ejmp.2010.12.003 27. Uradni list Republike Slovenije. Zakon o varstvu pred ionizirajočimi sevanji in jedrski varnosti [Internet]. 2018. Available from: http://www.pisrs.si/Pis.web/ pregledPredpisa?id=ZAKO7385 28. Page MJ, McKenzie JE, Bossuyt PM, Boutron I, Hoff mann TC, Mulrow CD, et al. The PRISMA 2020 statement: an updated guideline for reporting systematic reviews. BMJ 2021;372:n71. doi: 10.1136/bmj.n71 Matjašič A. / Diagnostic reference levels in dental radiology: a systematic review 30 Medical Imaging and Radiotherapy Journal (MIRTJ) 38 (2)