CT angiography of various superficial femoral artery stents: An in vitro phantom study

Purpose: To evaluate CT reconstruction parameters to improve stent lumen visualization in vitro. Material and methods: 12 latest superficial femoral artery (SFA) stents were placed in a vessel phantom (diameter 4.7 mm, intravascular attenuation 250 HU, extravascular density 50 HU). Stents were imaged with a 128-slice scanner (SOMATOM Definition Flash, Siemens, Germany) with standard parameters: 120 kV, 200 mAs, collimation 128 mm x 0.6 mm. Different reconstruction parameters were evaluated: B26f, B30f, B45f, B46f and B60f kernel; slice thickness of 0.6, 2.0 and 5.0 mm. To measure visualization characteristics, stent lumen diameter and intraluminal attenuation were assessed. Results: Best stent lumen visualization could be obtained using the B46f kernel (p < 0.001). The visible stent lumen ranged from 66.4% to 83.3% with a mean diameter of 77.7 +/- 4.6%. Nitinol stents showed a significant improved lumen visibility compared to the cobalt-chromium stent (p = 0.02). The most realistic lumen attenuation was achieved using the B46f kernel with a mean attenuation of 259.3 +/- 8.9 HU. The visible lumen diameter in protocols with 5 mm slice thickness was significantly lower (70.0 +/- 4.9%) compared to thinner slices (p < 0.001). Conclusion: CTA of SFA stents should be reconstructed with a slice thickness of 2.0 mm and a B46f kernel to achieve best image quality and to become more sensitive to exclude instent restenosis. (C) 2011 Elsevier Ireland Ltd. All rights reserved.