MR Imaging evaluation of the normal appendix in children and adolescents

Purpose: To evaluate asymptomatic children and adolescents to determine the rate of detection of the normal appendix at unenhanced magnetic resonance (MR) imaging. Materials and Methods: This study was approved by the medical ethics committees of the authors' institutions, and informed consent was obtained from participants' parents or guardians. Forty asymptomatic volunteers underwent MR imaging to detect the appendix. Mean age (+/- standard deviation) for the 18 boys was 12.8 years +/- 2.4 (range, 9-17 years) and for the 22 girls was 12.7 years +/- 2.7 (range, 8-17 years). The MR imaging protocol consisted of axial T1-weighted fast spin-echo (SE), axial and coronal T2-weighted fast SE, and axial T2-weighted fat-saturated fast SE sequences. Two observers interpreted results independently, and K coefficients were calculated to evaluate agreement. The rate of detection was defined as the percentage of times that the appendix was visualized with at least one sequence. Body mass index was recorded for all participants. Results: The normal appendix was detected by one observer in 19 cases (48%) and by the other in 20 cases (50%). The rate of appendix detection after observers reached a consensus was 48% (95% confidence interval: 32%, 64%). Interobserver agreement for appendix detection was good for most sequences analyzed. The greatest rate of normal appendix detection was found with the axial T2-weighted fast SE sequence (48%). Conclusion: The rate of normal appendix detection in children and adolescents at unenhanced MR imaging was 48%, which is similar to computed tomographic but lower than ultrasonographic detection rates. (c) RSNA, 2008.