Comparison of conventional and simulated reduced-tube current MDCT for evaluation of suspected appendicitis in the pediatric population

摘要

OBJECTIVE. The purpose of this study was to compare CT with conventional and simulated reduced-tube current in the evaluation for acute appendicitis in children. MATERIALS AND METHODS. Validated noise-addition (tube current-reduction) software was used to create 50% and 75% tube current reductions in 60 CT examinations performed for suspected appendicitis, resulting in 180 image sets. Three blinded pediatric radiologists scored the randomized studies for the following factors: presence of the normal appendix or appendicitis (5-point scale; 1 = definitely absent and 5 = definitely present), presence of alternate diagnoses, and overall image quality (1 = nondiagnostic and 5 = excellent). Truth was defined by the interpretation of the conventional examination. RESULTS. For conventional examinations, the total number of reviews (60 cases × 3 readers = 180) in which the normal appendix was identified was 120 of 180 (66.7%), compared with 108 of 180 (60%) in the 50% (p = 0.19) and 91 of 180 (50.6%) in the 75% (p = 0.002) tube current-reduction groups. Appendicitis was identified in a total of 39 of 180 (21.7%), 38 of 180 (21.1%), and 37 of 180 (20.6%) examinations, respectively (p > 0.05). This translates to sensitivities of 97% and 95% for the 50% and 75% tube current-reduction groups, respectively. Alternate diagnoses were detected in 14%, 16%, and 13% of scans, respectively. Compared with conventional-tube current examinations, reader confidence and assessment of image quality were significantly decreased for both tube current-reduction groups. CONCLUSION. Simulated tube current-reduction technology provides for systematic evaluation of diagnostic thresholds. Application of this technology in the setting of suspected appendicitis shows that tube current can be reduced by at least 50% without significantly affecting diagnostic quality, despite a decrease in reader confidence and assessment of image quality.