Objective To investigate the clinical value of multi-slice CT angiography (MSCTA) of lower limbs in patients with peripheral arterial occlusive disease (PAOD) using the test-bolus technique.Methods Forty-four patients with PAOD were enrolled consecutively in the study.In group I, 18 subjects underwent CTA by bolus triggering method and in group 2, 26 subjects underwent CTA by test-bolus technique.During scanning procedure in group 2 subjects, the bolus transit time to aorta ( TAO ), popliteal arteries (Tpop ) and aorto-popliteal bolus transit time (T,) were calculated through dynamic acquisition at their respective level and the delay time were immediately set as TAO and scan time as double Tt.Two independent senior attending physicians with training experience in interpreting CTA determined the quality of each arterial segment visualization based on 5 parameters (1.visible farthest branch, 2.clarity of vessels border, 3.presence of venous contamination, 4.grading of stenosis, 5.CT value at 4 arterial segments).Inter-observer agreement on imaging quality between readers was evaluated using Cohen's k statistic by calculating K values.X2 test and t test were used to compare the quality of images in both groups.Results In group 2 patients,a larger individual variation in transit time of the contrast to reach aorta was obserued [ TAO = ( 17.1 ± 2.6) s with a range of 12.0—22.0 s ] and aorto-popliteal transit time [ Tt = ( 14.8 ± 5.5 ) s with a range of 8.0—24.0 s ].CTA of group 2 patients demonstrated bettor quality over group I patients' CTA, especifieally in the infra-pop|iteal and foot area arteries. There was an excellent inter-observer agreement for group 2 patients ( K ＞ 0.80 ) whereas in group 1 agreement in infra-popliteal segments for venous contamination ( K value 0.60 ) and stenosis degree ( K value 0.50 ) were not satisfactory enough.Group 1 patients were reported to have more severe stonosis in infra-popliteal and foot arteries( X2 = 30.55 and22.41,P＜0.01).Conclusion There was a wide interindividual variation in transit time for contrast medium to reach aorta and pollteal artery. Adaptive method by using two low-dose test bolus injection determined interindividual variation in delay time and scan time and thus above parameters was able to produce better quality images than using bolus triggering technique in below knee and foot region arteries.