Background: Multi-slice computed tomography (MSCT) scanners with retrospective ECG-gating permit visualization of the coronary arteries. Limited spatial and temporal resolution as well as breathing artefacts due to the scan time can cause poor distal vessel segment and side branch visualization. The latest MSCT generation with true 16-detector slices (Sensation 16), Siemens, Forchheim, Germany) provides furthermore improved temporal and spatial resolution, as well as significantly reduced scan time. To assess, whether this technical improvement has also an impact on image quality we conducted the following study.
Methods and material: Sixty-two consecutive patients (33 male, 29 female, mean age 63+/-8 [47-79] years, heart rate after beta-blockade 63+/-7 [45-86] bpm) with suspicion of coronary artery disease (CAD) were examined by cardiac MSCT. Parameter settings were: 0.75 mm collimation, 2.8mm table feed/rotation, caudocranial scan direction, 80 cc contrast media biphasic injection protocol, gantry rotation time 375 ms, temporal resolution 188 ms). Thirteen coronary segments (sgts) were evaluated in each patient (total number: 806 sgts). Image quality of each segment was determined as: excellent--free of motion artefacts, good--mild motion artefacts, relevant artefacts--still diagnostic value, severe calcification and insufficient image quality--not visualized segment.
Results: 301/806 (37%) sgts showed excellent and 294/806 (36%) sgts good image quality. Relevant artefacts were seen in 107/806 (13%) sgts, calcifications in 41/806 (5%) sgts. 63/806 (8%) sgts could not be visualized (34 of them (54%) either segment 9 or 10). Diagnostic image quality was achieved in 702/806 (87%) sgts.
Conclusions: Due to true 16-slice technology and faster gantry rotation time MSCT image quality could be improved and allows a visualization of the entire coronary tree. Larger, randomized, catheter-controlled studies have to be conducted to determine, whether this improved visualization also translates into better diagnostic accuracy.