Lower Extremity Peripheral Arterial Diseases:Applicable Study Of Multislice Spiral CT Angiography

PurposeTo evaluate the clinical application of multislice spiral CT angiographic technique for diagnosis and assessment of the lower limb peripheral arteries diseases Materials and methods1. Twenty patients with suspected peripheral arterial diseases underwent CT angiography(CTA). They were divided into two groups randomly. The spiral scans cover renal artery to the artery of the lower extremity. Bolus tracking was used to monitor the enhancement of the artery in order to determine the best delay time. On one group contrast media was injected at a rate of 3.0ml/sec, and on the other group, the rate was 4.0ml/sec. We used Siemens Wizard workstation for further three dimensional reconstruction. And we compared the axial images with post-processing images.2. Conventional digital subtraction angiography (DSA) was performed as a standard reference in 33 patients within 4 weeks before or after performance of CTA. Quantitative and qualitative analysis of the DSA and CTA data were compared. The bilateral peripheral arterial trees were divided into 11 segments and the degree of the arterial stenosis was evaluated with five-grading system. The sensitivity, specificity, and accuracy were calculated for the demonstration of stenosis degrees, which wereshowed by CTA. Kappa statistical analysis was used to determine the effect of CTA. Results1. The lower limb arterial enhancement effect and the quality of reconstruction images in the group which using injection rate 4.0 ml/sec is better than the group of 3.0 ml/sec.2. The quality of source and post-processing images are satisfactory in all 33 patients who underwent CTA examination. Of the 693 segments studied, 683 were assessable on both DSA and CTA. Using the DSA images as the standard reference, the sensitivity, specificity, and accuracy of CTA were 97.6% ( 95% CI, 94.9%-100.7%), 98.9% (95% CI, 98.0%-99.8%), 98.7% (95% CI, 97.9%-99.5%) for detecting the occluding segments. With the regard the detection of segments that had more than moderate stenosis, the sensitivity, specificity, and accuracy of CTA were 98.9%(95% CI, 97.4%-100.4%), 99.4%( 95% CI, 98.7%-100.1%), 99.3%(95% CI, 92.4%-99.9%).3. Kappa statistical analysis was used to compare the result between CTA and DSA (K=0.86, CI 0.80-0.91). The results of both CTA and DSA in detection of peripheral arterial stenosis with 5 grading system were showed no difference after kappa statistical analysis.Conclusion1. Comparing with DSA , CTA has the same effect in demonstrating the position and the degree of peripheral arterial stenosis.2. As a non-invasive, high accurate, fast-acquisition, high-resolution technique for vascular imaging, CTA can replace DSA to a certain extent.