AJR:195, September 2010
Jonathon Leipsic, Troy M. LaBounty, Brett Heilbron, James K. Min, G. B.John Mancini, Fay Y.Lin, Carolyn Taylor, Allison Dunning, James P. Earls
OBJECTIVE. The purpose of our study was to determine the effect of Adaptive Statisti-cal Iterative Reconstruction (ASIR) on cardiac CT angiography (CTA) signal, noise, and im¬age quality.
MATERIALS AND METHODS. We evaluated 62 consecutive patients at three sites who underwent clinically indicated cardiac CTA using an ASIR-capable 64-MDCT scanner and a low-dose cardiac CTA technique. Studies were reconstructed using filtered back pro¬jection (FBP), ASIR-FBP composites using 20-80% ASIR, and 100% ASIR. The signal and noise were measured in the aortic root and each of the four coronary arteries. Two blinded readers graded image quality on a 5-point Likert scale and determined the proportion of in-terpretable segments. All segments were included for analysis regardless of size.
RESULTS. In comparison with FBP (0% ASIR), the use of 20%, 40%, 60%, 80%, and 100% ASIR resulted in reduced image noise between groups (-7%, -17%, -26%, -35%, and -43%, respectively; p < 0.001) without difference in signal (p = 0.60). There were signifi¬cant differences between groups (0%, 20%, 40%, 60%, 80%, and 100% ASIR) in the Likert scores (1.5, 2.1, 3.7, 3.8, 2.0, and 1.1, respectively; p < 0.001) and proportion of interpretable segments (88.7%, 89.3%, 90.5%, 90.4%, 88.0%, and 87.3%, respectively;p < 0.001). Recon-struction using 40% and 60% ASIR had the highest Likert scores and largest proportion of in-terpretable segments. In comparison with FBP, each was associated with higher Likert scores and increased interpretable segments (p < 0.001 for all).
CONCLUSION. ASIR resulted in noise reduction and significantly impacted image quality. When using a low tube current technique, cardiac CTA reconstruction using 40% or 60% ASIR significantly improved image quality and the proportion of interpretable segments compared with FBP reconstruction.