Assessment of 1 mSv Urinary Tract Stone CT With Model-Based Iterative Reconstruction

OBJECTIVE. The purpose of this study was to evaluate stone detection, assessment of secondary signs of stone disease, and diagnostic confidence utilizing submillisievert CT with model-based iterative reconstruction (MBIR) in a North American population with diverse body habitus. MATERIALS AND METHODS. Fifty-two adults underwent stone CT using a split-dose protocol; weight-based projected volume CT dose index (CTDIvol) and dose-length product (DLP) were divided into two separate acquisitions at 80% and 20% dose levels. Images were reconstructed with MBIR. Five blinded readers counted stones in three size categories and rated “overall diagnostic confidence” and “detectability of secondary signs of stone disease” on a 0–4 scale at both dose levels. Effective dose (ED) in mSv was calculated as DLP multiplied by conversion coefficient, k, equal to 0.017. RESULTS. Mean ED (80%, 3.90 ± 1.44 mSv; vs 20%, 0.97 ± 0.34 mSv [p < 0.001]) and number of stones detected (80%, 193.6 ± 25.0; vs 20%, 154.4 ± 15.4 [p = 0.03]...