Clinical impact and cost-effectiveness of noncontrast MRI in the evaluation of suspected appendiceal abscesses in children.

BACKGROUND

Noncontrast MRI has been shown to be feasible in children with postappendectomy abscesses and helps guide clinical management, but its role in preoperative appendiceal abscesses is unclear.

PURPOSE: To determine the cost-effectiveness and impact on clinical management of noncontrast MRI in pediatric patients with suspected appendiceal abscess, both pre- and postappendectomy.

STUDY TYPE: Retrospective cohort study.

POPULATION: In all, 82 children under the age of 18 years with suspected appendiceal abscess on ultrasound.

FIELD STRENGTH/SEQUENCE: Diffusion-weighted imaging and T2 -weighted single-shot fast spin-echo imaging of the abdomen and pelvis at 1.5T and 3T.

ASSESSMENT: The presence, location, size, and apparent diffusion coefficient (ADC) of fluid collections and the presence of a drainage path was noted by three pediatric radiologists. Imaging time, completeness of the exam, and impact on clinical management was recorded. The incremental cost-effectiveness ratio was calculated for MRI relative to CT, taking into account hospital charges, radiation exposure, and risk of adverse reaction to iodinated contrast.

STATISTICAL TESTS: Descriptive statistics were used. Intraclass correlation coefficient and Fleiss' kappa were used to assess interobserver variation. Proportions were compared using Fisher's exact test (statistical significance at P < 0.05).

RESULTS

MRI confirmed the presence of collections in most cases, with alternative diagnosis established in 10 patients (Tubo-ovarian abscess n = 7, Crohn's disease, ileal anastomotic leak, and Birkitts lymphoma each n = 1). MRI showed the presence of a safe drainage pathway in 92-97% of pelvic abscesses and 86-98% of abdominal abscesses compared with 7-10% and 75-81%, respectively, for ultrasound. MR was cost-effective compared with CT, taking into account the direct charges, risk of radiation induced cancer, and adverse reaction to iodinated contrast.

DATA

CONCLUSION

Noncontrast MR is cost-effective and affects clinical management in a significant proportion of children with suspected appendiceal abscesses.

LEVEL OF EVIDENCE: 5 Technical Efficacy: Stage 6 J. Magn. Reson. Imaging 2019.