A new approach for prospectively gated cardiac rotational angiography

Cardiac rotational angiography (RA) is well suited for 3-D cardiac imaging during catheter based interventions but remained limited to static images or was characterized by high dose patient radiation dose. We present a new prospective imaging technique that is capable of imaging the dynamics of the cardiac cavities in a single C-arm run during the intervention with a relatively low dose. By combining slow atrial pacing to obtain a stable heart rhythm and a single C-arm rotation with imaging at a regular imaging interval, a prospective 4DRA is established. Pacing interval and imaging framerate can be adapted such that a single cardiac phase is imaged multiple times and a motion free state is imaged from different equiangular positions. A practical implementation of this technique was realized in which the cardiac cavities are imaged while pacing at 105 bpm (574 msec) and imaging at approximately 15 fps. A number of animal experiments were conducted in which the technique was applied and MR imaging was performed subsequently. Quantitative comparison was made by manual contouring of the left ventricle in the RA and MR images of both end-systolic and end-diastolic phases. Reconstructed images of the individual cardiac phases showed all four chambers and important vessels in spite of substantial image noise. 4DRA and MR absolute surface distance errors amounted to 2:8 ± 0:7 mm, which is acceptable. Further, no systematic difference could be identified. Finally, it is expected that the effective dose of a clinical protocol with 381 images will be lower than the current retrospective gated RA protocols.