Diagnosis of arterial disease of the lower extremities with duplex scanning: a validation study.

Background: While standard x-ray arteriography remains the traditional gold standard for peripheral arterial imaging, it has obvious limitations and is associated with significant local and systemic complications. Technological advances in duplex ultrasonography have allowed lower-extremity arterial mapping, primarily of the femoropopliteal segment, based on morphological and hemodynamic parameters. However, inadequate sonographic visualization of the infrapopliteal arteries is seen as a major limiting factor for the liberal use of duplex ultrasonography as a sole preoperative imaging modality. Others have documented the feasibility and reliability of infrapopliteal duplex ultrasound arterial mapping. These divergent results may be partially explained by the operator-dependent nature of this exam and different types of scanners utilized by various investigators. To date, there has been no validation study done in the Philippine Heart Center on the duplex sonographic evaluation of the peripheral arteries in patients suspected of having peripheral arterial occlusive disease. This study was conducted to determine the diagnostic accuracy of duplexscanning in patients suspected of having peripheral arterial disease.

Methods: This was a cross-sectional validation study involving duplex ultrasonography studies of femoral arterial segments of patients suspected of peripheral arterial disease. The results of these were compared to the results obtained using subtraction angiography. Each segment was graded as normal, <50% stenosis, > 50% stenosis, near total-occlusion, and total occlusion. The duplex scan results were evaluated independently by two vascular specialists while the arteriogram result was evaluated by an experienced interventional cardiologist. The Kappa statistic was used to examine the level of agreement between angiography and ultrasound.

Results: The Kappa level (95% confidence interval) of agreement between ultrasound and angiographic assessments for distinguishing hemodynamically significant (>50%) stenosis was 0.55. Poorest agreement was observed from ultrasound assessments of the popliteal artery as compared to the other arterial segments studied.

Conclusion: It has been demonstrated that Duplex ultrasonography produces satisfactory agreement with arteriography for the diagnosis of peripheral arterial occlusive disease, and this technique can even limit the need for arteriography in assessing this subset of patients.