AJR:215, November 2020 1 Unenhanced MRI of the Abdomen and Pelvis in the Comprehensive Evaluation of Acute Atraumatic Abdominal Pain in Children Joshua Warner 1 Sarah Desoky Hina Arif Tiwari Frank Morello Dorothy Gilbertson Unni Udayasankar Warner J, Desoky S, Tiwari HA, Morello F, Gilbert- son D, Udayasankar U 1 All authors: Department of Medical Imaging, University of Arizona College of Medicine, Banner University Medical Center, 1501 N Campbell Ave, PO Box 245067, Tucson, AZ 85724-5067. Address correspondence to U. Udayasankar (unniu@radiology.arizona.edu). Pediatric Imaging • Review AJR 2020; 215:1–11 ISSN-L 0361–803X/20/2155–1 © American Roentgen Ray Society Keywords: abdominal pain, appendicitis, MRI, pyelonephritis, torsion doi.org/10.2214/AJR.19.22577 Received November 17, 2019; accepted after revision March 9, 2020. Based on a presentation at the ARRS 2019 Annual Meeting, Los Angeles, CA. MRI as a frst-line imaging protocol in this clinical setting [17, 18]. On the basis of fnd- ings in the body of literature and our own ex- perience, we conclude that gadolinium-based contrast is not required to sustain high diag- nostic performance, which avoids recently posed concerns about gadolinium deposition [17, 19]. Effciency and examination compli- ance are increased because there is no need to obtain and protect IV access or administer en- teric contrast medium. Use of MRI for the evaluation of acute atraumatic abdominal pain in pediatric pa- tients is on the rise [20]. However, the litera- ture and the American College of Radiology guidelines are mostly focused on appendici- tis; there is incomplete guidance available for atypical presentations and for instanc- es in which fndings from examination and overall clinical assessment are equivocal. For children with certain well-established disorders and for those with specifc clinical scenarios, MRI has been extensively used to identify intraabdominal abnormalities or disease complications. A specialized MRI protocol is often used for these patients, in- cluding MRCP for the evaluation of biliary abnormalities, MR enterography for the set- ting of acute fare-up of infammatory bowel disease, and a pelvic protocol for suspected cases of ovarian torsion. Our protocol was created to address the common clinical sce- nario of needing to assess nonspecifc acute abdominal pain in children who do not have a preexisting disease process by using one A cute atraumatic emergent abdomi- nal pain is a challenging presenta- tion in pediatric patients, having many potential underlying causes [1–5]. The diagnosis and management of these patients is further complicated by variable pa- tient cooperation and interaction with evaluat- ing providers who are increasingly reliant on imaging for diagnosis and management [6]. Acute appendicitis is the most common cause of abdominal pain requiring surgical consulta- tion, but it represents only a small number of presentations overall. There is also variation in the prevalence of appendicitis related to age and sex [7–9], with negative appendectomy rates holding steady at approximately 5%, de- spite the availability of modern imaging tech- niques. The only American College of Radiol- ogy Appropriateness Criteria available to guide pediatric abdominal imaging in the emergent setting are for suspected appendicitis [10]. De- pending on the severity of the presentation and suspicion for complications, ultrasound is cur- rently recommended for initial assessment [10, 11], although more advanced imaging may be considered for defnitive assessment. Regarding cross-sectional imaging per- formed in the setting of acute atraumatic emergent abdominal pain, multiple prior stud- ies and meta-analyses comparing unenhanced MRI versus CT for the detection of appendi- citis revealed similar excellent diagnostic per- formance, with MRI having the obvious ad- vantage of not requiring ionizing radiation [12–16]. Multiple institutions described using OBJECTIVE. The purpose of this study is to show the utility of rapid unenhanced MRI in the comprehensive assessment of acute atraumatic abdominal pain in children, including ap- pendicitis and alternate diagnoses, and to review the MRI features of common acute abdomi- nal and pelvic conditions in a large, single-institution cohort. CONCLUSION. Rapid unenhanced MRI is an excellent option for the initial, compre- hensive evaluation of acute abdominal emergencies in pediatric patients because it can diag- nose the full range of presenting abnormalities, including causes of abdominal pain warrant- ing surgical and nonsurgical management. Warner et al. Unenhanced MRI for Abdominopelvic Pain in Children Pediatric Imaging Review American Journal of Roentgenology