Comparison of Conventional and Simulated Reduced–Tube Current MDCT for Evaluation of Suspected Appendicitis in the Pediatric Population

Abstract

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.

Comparison of filtered back projection and iterative reconstruction in diagnosing appendicitis at 2-mSv CT

“…The dose-simulation technique, which simulates dose reduction at multiple levels with a single scan, can be a more favorable methodology free of clinical and ethical concerns. This technique has been introduced for a systematic exploration of reduced dose levels [43,44], but it has not yet been studied in conjunction with IR in clinical research. While we tested 2-mSv appendiceal CT and showed that IR did not exhibit any diagnostic advantage over FBP, our results can justify future studies exploring an even more dramatically reduced dose level (e.g., 1 mSv or sub-mSv) at which IR might truly benefit.…”

A Simulation Paradigm for Evaluation of Subtle Liver Lesions at Pediatric CT: Performance and Confidence

“…The development of noise addition paradigms and lesion insertion tools have allowed for investigations that use one set of patient scans to create multiple simulated data sets without additional radiation exposure (11). A validated lesion insertion software tool found that observers could not readily distinguish real liver lesions from simulated anthropomorphic liver lesions (12).…”

“…Although the primary outcome measure for dose reduction investigations is reader accuracy (11,13), other factors play into the clinical applications. For example, confidence levels and examination review times may relate to fatigue but do not necessarily affect performance.…”