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

Rationale MRI is increasingly used for diagnosis of pediatric appendicitis in the emergency 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 for diagnosis.

Initial MRI protocol implemented for suspected appendicitis included five respiratory-triggered axial and coronal single shot fast spin echo (SSFSE) and radial T2W sequences with and without fat suppression (FS). This protocol was reassessed based on image quality. Subsequently, the coronal and axial T2W SSFSE FS sequence were removed. A three-sequence exam comprised the rapid MRI appendicitis protocol used for the remainder of the study. All examinations were performed on a 1.5 T scanner. For all examinations, the following information was obtained: scan time, diagnosis of appendicitis (by radiology report), surgery and pathology reports, and alternative diagnoses documented in radiology reports. MRI examination scan durations were compared between the five-sequence and three-sequence protocols, with Mann-Whitney U test, and proportions of false diagnoses were compared to Fisher'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 three sequence protocol (p < 0.0001). The majority (n = 157, 80.5% of 195) of examinations were performed in a goal time of< 15 min. 23 examinations took longer than 20 min (n = 12, n = 11 for the three- and five-sequence protocols, respectively) were due to repeat sequences or addition of non-standard sequences (requested by interpreting radiologist). 27 (90%) of the 30 reported positive cases were confirmed by pathology. There were three false-positive diagnoses (all three-sequence protocol exams) and one false-negative diagnosis (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 be performed in less than 15 min in the emergency department and has high diagnostic accuracy for acute appendicitis in children and young adults.