Cardiac imaging with retrospectively ECG-gated fast multi-slice spiral CT

Purpose: In this paper a method for cardiac imaging with fast multi-slice C T and retrospectively EGG-gated spiral acquisition is presented. Methods: A fast multi-slice CT system with 4 simultaneously acquired slices and 0.5 s rotation time is used (Siemens Somatom VolumeZoom). Continuous s piral data of the entire heart volume is acquired together with the patient 's ECG and reconstructed with dedicated spiral algorithms providing 250 ms temporal resolution. Three-dimensional image data sets are built up from ov erlapping slices that are reconstructed in an arbitrary, user-defined phase of the heart cycle (e.g. diastolic phase). To evaluate the capability of t he method for functional imaging complete three-dimensional image volumes a re reconstructed from the same spiral data set in different phases of the h eart cycle. Results: A spiral data set of the entire heart volume may be acquired withi n a single breath-hold. Typical scan times for standard examinations with 3 mm slice width are 10-15 s, and for high-resolution CT angiographies of th e coronary arteries with 1.25 mm slice width about 30-35 s. Motion-free rec onstruction of the heart and coronary arteries with high spatial resolution is possible in the diastolic phase of the heart cycle. Multi-phase reconst ructions from the same spiral scan data set are possible, however, motion a rtifacts in heart phases with fast cardiac motion may not be completely avo ided. Conclusion: Fast multi-slice spiral CT with retrospectively EGG-gated spira l reconstruction is well suited for th ree-dimensional and functional imagi ng of the heart, especially for high-resolution imaging of calcified corona ry plaques and CT-angiography of the coronary arteries.