Technical and Diagnostic Performance of Rapid MRI for Evaluation of Appendicitis in a Pediatric Emergency Department

Abstract

Rationale MRI is increasingly used for diagnosis of pediatric appendicitis in theemergency care setting. Scan and room time are important to optimize workflow,especially in situations with limited MRI availability and accessibility. To describe our process to optimize and implement a rapid, non-contrast, free-breathing MRI protocol for appendicitis and to characterize the accuracy fordiagnosis. Initial MRI protocol implemented for suspected appendicitis included five respiratory-triggered axial and coronal single shot fast spin echo (SSFSE) and radialT2W sequences with and without fat suppression (FS). This protocol was reassessedbased on image quality. Subsequently, the coronal and axial T2W SSFSE FS sequence were removed. A three-sequence exam comprised the rapid MRI appendicitisprotocol used for the remainder of the study. All examinations were performed on a 1.5T scanner. For all examinations, the following information was obtained: scan time, diagnosis ofappendicitis (by radiology report), surgery and pathology reports, and alternativediagnoses documented in radiology reports. MRI examination scan durations werecompared between the five-sequence and three-sequence protocols, with Mann-Whitney U test, and proportions of false diagnoses were compared toFisher's exact test. 216 examinations were performed; 21 and 195 performed with five-and three-sequence protocol, respectively. The median duration of the five-sequence protocol was 20 (16.9-23.5) minutes vs.11 (9.5-13) minutes for the threesequence protocol (p<0.0001). The majority (n=157, 80.5% of 195) of examinations were performed in a goal time of<15min. 23 examinations took longer than 20min (n=12, n=11 for the three-and five-sequence protocols, respectively) were due to repeat sequences or addition of non-standardsequences (requested by interpreting radiologist). 27 (90%) of the 30 reported positive cases were confirmed by pathology. There were threefalse-positive diagnoses (all three-sequence protocol exams) and onefalse-negativediagnosis (five-sequence protocol exam). Alternative diagnoses, including pancreatitis,omental infarct, masses, and ovarian pathology, were made in 42 (19%) cases. A three-sequence, non-contrast, free- breathing MRI examination can beperformed in less than 15min in the emergency department and has highdiagnostic accuracy for acute appendicitis in children and young adults.