Wieland H. Sommer MD, Presenter: Nothing to Disclose

Andreas Helck MD, Abstract Co-Author: Nothing to Disclose

Thorsten R.C. Johnson MD, Abstract Co-Author: Speakers Bureau, Siemens AG Research grant, Bayer AG

Maximilian F. Reiser MD, Abstract Co-Author: Nothing to Disclose

Hans-Christoph Richard F. Becker MD, Abstract Co-Author: Nothing to Disclose

Konstantin Nikolaou MD, Abstract Co-Author: Nothing to Disclose

To evaluate the accuracy of time-resolved CT-angiography (TR-CTA) of the lower leg in patients with peripheral arterial disease (PAD).

60 patients with known or suspected PAD underwent standard peripheral run-off CTA (120kV, 1mm slice thickness, scan range: 130 cm, 100 ml Imeron400, Bracco, Italy) and an additional TR-CTA of the lower leg. TR-CTA was performed on a 128-slice CT-Scanner (Somatom Definition AS+, Siemens Healthcare) with a continuous bidirectional table movement for time-resolved imaging. 12 low dose phases of the lower leg were recorded (scan range: 27 cm, scanning time 30 s, temporal resolution, 2.5s, 80kVp, 120 mAs, mean effective dose: 0.18 mSv, 60ml contrast medium). Both in TR-CTA and standard-CTA, arterial enhancement and confidence of diagnosis were assessed on a 3-point-scale (1-3, 1=best). Additionally, presence of significant stenoses (>50%) was evaluated. All assessments were performed separately for 7 segments of each lower leg (total of 840 segments). In 20 of 60 patients reference imaging (MRA and/or DSA) was available for diagnostic comparison.

Selecting the best out of 12 phases, TR-CTA showed a better arterial enhancement than standard-CTA (TR-CTA: 1.24±0.50; standard-CTA: 1.60±0.66; p<0.0001). Diagnostic confidence was higher in TR-CTA (TR-CTA: 1.33±0.50; standard-CTA: 1.72±0.66; p<0.0001). In the 20 patients available for diagnostic comparison, 139 of 280 segments showed significant disease. Diagnostic accuracy for TR-CTA and standard-CTA of the lower leg was 96% and 88%, respectively.

TR-CTA of the lower leg leads to advantages of arterial contrast enhancement and avoids problems like venous overlay and early data acquisition before arrival of contrast agent. Furthermore, diagnostic accuracy and diagnostic confidence is improved as compared to standard-CTA.

Standard-CTA of lower leg arteries is especially limited in patients with severe PAD. These limitations can in part be overcome by TR-CTA of the lower leg.

Sommer, W, Helck, A, Johnson, T, Reiser, M, Becker, H, Nikolaou, K, Time-Resolved CT Angiography of the Lower Leg in the Diagnosis of Peripheral Arterial Disease.  Radiological Society of North America 2009 Scientific Assembly and Annual Meeting, November 29 - December 4, 2009 ,Chicago IL. http://archive.rsna.org/2009/8014909.html