To assess the performance of a motion map algorithm to automatically determine the optimal systolic and
diastolic reconstruction window for coronary CT Angiography using Dual Source CT.
Materials and Methods:
Dual Source coronary CT angiography data sets (Somatom Definition, Siemens Medical Solutions) from 50
consecutive patients were included in the analysis. Optimal systolic and diastolic reconstruction windows were
determined using a motion map algorithm (BestPhase, Siemens Medical Solutions). Additionally data sets were
reconstructed in 5% steps throughout the RR-interval. For each major vessel (RCA, LAD and LCX) an optimal
systolic and diastolic reconstruction window was manually determined by two independent readers using volume
rendering displays. Image quality was rated using a five-point scale (1 = no motion artifacts, 5 = severe motion
artifacts over entire length of the vessel).
The mean heart rate during the scan was 72.4bpm (±15.8bpm). Median systolic and diastolic reconstruction
windows using the BestPhase algorithm were at 37% and 73% RR. The median manually selected systolic
reconstruction window was 35 %, 30% and 35% for RCA, LAD, and LCX. For all vessels the median observer
selected diastolic reconstruction window was 75%. Mean image quality using the BestPhase algorithm was 2.4
±0.9 for systolic reconstructions and 1.9 ±1.1 for diastolic reconstructions. Using the manual approach, the mean
image quality was 1.9 ±0.5 and 1.7 ±0.8 respectively. There was a significant difference in image quality
between automatically and manually determined systolic reconstructions (p<0.01) but there was no significant
difference in image quality in diastolic reconstructions.
Automatic determination of the optimal reconstruction interval using the BestPhase algorithm is feasible and
yields reconstruction windows similar to observer selected reconstruction windows. In diastolic reconstructions
overall image quality is similar to the image quality in manually selected reconstruction windows.