CT-angiography of the carotid artery: First results with a novel 16-slice-spiral-CT scanner

Purpose: To evaluate a novel multislice CT system (16-slice-spiral-CT scanner) for the diagnosis of carotid artery stenosis. Material and Methods: Five patients with symptomatic atherosclerotic disease of the carotid arteries were examined with a 16-slice-spiral-CT scanner. Collimation was 16x0.75mm, table speed 36 mm/s (pitch of 1.5), rotation time 0.5 s, tube current was 160 eff.mAs at 120 kV. 60 ml of contrast material were injected with a power injector followed by a saline flush. The start delay was measured with test bolus method (20 ml CM). Interactive multiplanar reformation (iMPR) and thin slab MIP as well as volume rendering were used for image evaluation and presentation. Results: Scan time was 9 s for a range of 300 mm. This allowed imaging the whole length of the carotid artery (aortic arch to circle of Willis) in a true arterial phase. Pulsation artefacts did not impair the evaluation of the vessels at the level of the aortic arch. Overall image quality of both "source images" and 3D-reconstructions was excellent, due to a reduced voxel size of 0.03 mm(3). Image evaluation and postprocessing (iMPR, MIP) was done within 15 min. iMPR was highly accurate for demonstrating plaque morphology and determining the percentage of the stenosis. Conclusion: For the first time, true arterial phase images of the entire carotid artery with high spatial resolution could be acquired using a 16-slice-spiral-CT scanner. This method offers the potential to replace catheter angiography in the evaluation of carotid artery stenosis.