A COMPARISON BETWEEN COLOR DUPLEX ULTRASONOGRAPHY AND ARTERIOGRAPHY FOR IMAGING INFRAPOPLITEAL ARTERIAL LESIONS

Objective: To investigate the agreement between colour duplex ultrason ography and digital subtraction arteriography of the infrapopliteal ar teries. Design: Retrospective, blinded study. Setting: Vascular labora tory and Radiology Department, University Hospital. Methods: The infra popliteal vasculature was examined in a total of 51 limbs by both colo ur duplex ultrasound and digital subtraction angiography. By examining all arteries from the distal popliteal to the pedal arteries, a total of 204 individual arterial segments were available for analysis. Each segment was graded as 0-49%, 50-99% diameter reduced or occluded by b oth modalities. Using ultrasound, classification of stenoses was achie ved by observing peak systolic velocity ratios; a doubling of peak sys tolic velocity indicating a greater than or equal to 50% diameter redu cing stenosis. Where no Doppler signal could be obtained, the vessel w as assumed to be occluded. From angiographic studies, two radiologists separately and blindly assessed the extent of disease for each infrap opliteal artery noting areas of greater than or equal to 50% diameter reduction and occlusion. The Kappa statistic was used to examine the l evel of agreement between angiography and ultrasound as well as betwee n both radiologists. Results: The Kappa level (95% confidence interval ) of agreement between ultrasound and angiographic assessments for dis tinguishing patent from occluded segments was 0.61 (0.49-0.74) for all segments. The equivalent agreement between radiologists was 0.80 (0.7 0-0.89). Poorest agreement was observed from ultrasound assessments of the peroneal and tibio-peroneal trunk arterial segments. Conclusion: Since agreement between colour duplex scanning and angiography never f ell significantly below levels achieved between two radiologists, we c onclude that colour duplex ultrasound can be used to assess infrapopli teal artery patency.