Quantitative and qualitative evaluation of the influence of different table feeds on visualization of peripheral arteries in CT angiography of aortoiliac and lower extremity arteries

The influence of different table feeds (TF) on vascular enhancement and image quality in patients undergoing lower extremity runoff-CTA for peripheral artery occlusive disease (PAOD), acute ischemia (AI) or abdominal aortic aneurysm (AAA) with PAOD was investigated retrospectively. One hundred eighty-five patients (PAOD: n=132; AI: n=40; AAA: n=13) underwent 16-detector runoff-CTA (120 kV; 140 mAs; rotation time 0.5 s, collimation 16 x 1.5 mm) using different TF (30 mm/s: n=25; 40 mm/s: n=91; 48 mm/s: n=36; 56 mm/s: n=33). Vascular enhancement of the large arteries was measured every 10cm along the z-axis from the upper abdomen to the toe. Arterial enhancement in the distal lower leg was compared (ANOVA, Bonferroni post-test). Qualitative assessment of bolus timing was performed independently by two radiologists. The study was IRB approved. In patients with PAOD or AI, enhancement of calf arteries using a TF of 48 mm/s (278±79 HU) was significantly higher in comparison to two slower TF (30 mm/s: 201±70 HU, P<0.001; 40 mm/s: 251±79 HU, P<0.05; 56 mm/s: 261±57 HU, NS) and the fewest noninterpretable arterial segments below the knee were observed with a TF of 48 mm/s (reader 1: 5/12=4.1%; reader 2: 4/121=3.3%). In patients with AAA, the fewest nondiagnostic segments occurred with a TF of 30 mm/s (2/12=17%, both readers) and 40 mm/s (4/24=17%, both readers). A TF of 48 mm/s provided the best synchronization of CT data acquisition and contrast bolus propagation and thus the best image quality in patients with PAOD and AI. In patients with AAA, a slower TF of 30 mm/s provided better image quality than faster CT protocols. (orig.)