Wieland H. Sommer MD, Presenter: Nothing to Disclose

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

Fabian Bamberg 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

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

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

25 patients with known advanced PAOD underwent both Digital subtraction angiography of both lower legs (DSA) and a dedicated peripheral run-off CTA protocol, consisting of two contrast injections: A standard run-off from the diaphragm to the toes (120kV, 1mm slice thickness, scan range: 130 cm, 100 ml Imeron400, Bracco, Italy) was followed by an additional TR-CTA of the lower leg. TR-CTA was performed on a 128-slice CT-Scanner (Somatom Flash, Siemens Healthcare) with a continuous bidirectional table movement for time-resolved imaging. 8 low dose phases of the lower leg were recorded (scan range: 48 cm, temporal resolution: 3.5s/scan, total scan time: 28s, 80kVp, 120 mAs, mean effective dose: 0.26 mSv, 50ml 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, stenoses (<50%; 50-99%; occlusion) were rated in both CT datasets, separately for 7 segments of each lower leg (total, 350 segments), using DSA as gold standard.

Selecting the best out of 8 phases, TR-CTA showed a higher mean arterial enhancement than standard-CTA (TR-CTA: 1.36±0.54; standard-CTA: 1.58±0.58; p<0.0001). According to DSA serving as the diagnostic standard of reference, 129 of 350 segments (37%) showed significant disease (>50% stenosis). Diagnostic accuracy for stenosis rating (3-point-scale) was 89.7% for standard-CTA and 93.7% for TR-CTA (p<0.05). Sensitivity/Specificity for the detection of significant stenosis (>50%; present yes/no) were 93.5%/91.6% for standard CTA and 96.1%/96.8% for TR-CTA, respectively (p<0.05).

TR-CTA provides better arterial contrast enhancement in patients with advanced PAOD. The dynamic information leads to a higher diagnostic accuracy in the assessment of significant stenoses, as compared to a standard, single-phase run-off CTA.

Standard-CTA of lower leg arteries can be of limited image quality and diagnostic value in patients with advanced stages of PAOD. These limitations can partially be overcome by a dynamic CTA.

Sommer, W, Helck, A, Bamberg, F, Johnson, T, Reiser, M, Nikolaou, K, Diagnostic Accuracy of Dynamic CT Angiography of the Lower Leg in Patients with Advanced Peripheral Arterial Occlusive Disease.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9008886.html