Abstract 21243: Evaluation of Heavily Calcified Vessels with Coronary CT Angiography: Comparison of Iterative and Filtered Back Projection Image Reconstruction Techniques
Introduction: Heavy calcifications remain a limitation of coronary CT angiography (cCTA) and decrease the accuracy of this test for stenosis detection. Hypothesis We assessed the hypothesis that the novel iterative image reconstruction technique allows for more precise delineation of calcified plaques at cCTA in comparison to traditional filtered back projection (FBP).
Methods: Dual source cCTA studies of 30 patients (18men; 57±11 years) with Agatston scores of >400 were included prospectively. Image reconstruction was performed with FBP and with iterative reconstruction in image space (IRIS) using corresponding vascular algorithms. Image noise was evaluated in a region of interest in the aortic root. To compare the two reconstruction techniques regarding calcified plaque delineation, the volume of heavy coronary artery calcifications was measured using a threshold based volumetry tool. Two experienced, blinded observers subjectively rated image quality on a 5-point scale and interpreted both, FBP and IRIS series for significant (>50%) stenosis using the AHA 17-segment model. Results were compared with cardiac catheterization.
Results: Image quality of IRIS studies was rated significantly (p=0.04) higher than that of FBP reconstructions. Mean image noise was significantly lower with IRIS (26.8±11.1) than with FBP (33.4±10.6, p<0.01). Calcifications measured significantly lower in studies that were reconstructed with IRIS compared to FBP reconstructed studies (34.1±25.0mm3 versus 39.0±25.9mm3, p=0.04). There was incremental improvement in stenosis detection with IRIS (accuracy 96%, sensitivity 90%, specificity 96%, NPV 98%, PPV 76%) over FBP (accuracy 93%, sensitivity 85%, specificity 95%, NPV 97%, PPV 75%) when compared with cardiac catheter.
Conclusions: In conclusion, use of IRIS instead of FBP increases the accuracy of stenosis detection with cCTA in heavily calcified vessels by enabling a more precise delineation of calcified vessel segments.
- © 2010 by American Heart Association, Inc.