Fig. 2.

CT angiography (CTA) acquisition: Effect of scan range length in CTA: With prospective protocols in third-generation dual-source CTA the collimation is adapted to the set scan length. In regular cardiac examinations, this helps to avoid overscanning and results in an interpatient variability of the coverage per stack. When scanning heart valves full heart coverage is not always necessary and a shorter range may be sufficient. Special care should be taken in planning the scan range, however, so the largest possible z coverage per stack is obtained to avoid stack artefacts at the valve level. A A short scan range consisting of two stacks will result in potential stack artefacts through the valve. B A slightly longer scan range will result in three thin collimate stacks with the valve in the middle of the mid stack. Heart motion and respiratory variability might still move the valve into the potential stack artefacts. C Opening the scan length to exactly 14 cm will result in three stacks with maximum stack coverage ensuring valve images without ECG stack artefacts