Performance characteristics of magnetic resonance imaging without contrast agents or sedation in pediatric appendicitis

• Published in: Pediatric radiology Vol. 47; no. 10; pp. 1312 - 1320
• Main Authors: Didier, Ryne A., Hopkins, Katharine L., Coakley, Fergus V., Krishnaswami, Sanjay, Spiro, David M., Foster, Bryan R.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.09.2017; Springer Nature B.V
• Subjects: Adolescent; Age; Anesthesia; Appendicitis; Appendicitis - diagnostic imaging; Appendix; Child; Child, Preschool; Contrast agents; Criteria; Diagnosis; Diagnosis, Differential; Diagnostic systems; Female; Humans; Imaging; Magnetic resonance imaging; Magnetic Resonance Imaging - methods; Male; Medicine; Medicine & Public Health; Neuroradiology; NMR; Nuclear magnetic resonance; Nuclear Medicine; Oncology; Optimization; Original Article; Pediatrics; Predictive Value of Tests; Radiology; Resonance; Sensitivity; Ultrasound; Wall thickness; Gastrointestinal radiology; Children; Magnetic resonance imaging; Appendicitis; Appendix
• ISSN: 0301-0449; 1432-1998
• DOI: 10.1007/s00247-017-3897-7

Background Magnetic resonance imaging (MRI) has emerged as a promising modality for evaluating pediatric appendicitis. However optimal imaging protocols, including roles of contrast agents and sedation, have not been established and diagnostic criteria have not been fully evaluated. Objective To investigate performance characteristics of rapid MRI without contrast agents or sedation in the diagnosis of pediatric appendicitis. Materials and methods We included patients ages 4–18 years with suspicion of appendicitis who underwent rapid MRI between October 2013 and March 2015 without contrast agent or sedation. After two-radiologist review, we determined performance characteristics of individual diagnostic criteria and aggregate diagnostic criteria by comparing MRI results to clinical outcomes. We used receiver operating characteristic (ROC) curves to determine cut-points for appendiceal diameter and wall thickness for optimization of predictive power, and we calculated area under the curve (AUC) as a measure of test accuracy. Results Ninety-eight MRI examinations were performed in 97 subjects. Overall, MRI had a 94% sensitivity, 95% specificity, 91% positive predictive value and 97% negative predictive value. Optimal cut-points for appendiceal diameter and wall thickness were ≥7 mm and ≥2 mm, respectively. Independently, those cut-points produced sensitivities of 91% and 84% and specificities of 84% and 43%. Presence of intraluminal fluid (30/33) or localized periappendiceal fluid (32/33) showed a significant association with acute appendicitis ( P <0.01), with sensitivities of 91% and 97% and specificities of 60% and 50%. For examinations in which the appendix was not identified by one or both reviewers (23/98), the clinical outcome was negative. Conclusion Rapid MRI without contrast agents or sedation is accurate for diagnosis of pediatric appendicitis when multiple diagnostic criteria are considered in aggregate. Individual diagnostic criteria including optimized cut-points of ≥7 mm for diameter and ≥2 mm for wall thickness demonstrate high sensitivities but relatively low specificities. Nonvisualization of the appendix favors a negative diagnosis.