Power Doppler imaging: initial evaluation as a screening examination for carotid artery stenosis.

PURPOSE To evaluate power Doppler imaging as a possible screening examination for carotid artery stenosis. MATERIALS AND METHODS In the principal pilot study, a prospective, blinded comparison of power Doppler imaging with duplex Doppler imaging, the reference-standard method, was conducted in 100 consecutive patients routinely referred for carotid artery imaging at a large, private multispecialty clinic. In the validation pilot study, a prospective, blinded comparison of power Doppler imaging with digital subtraction angiography, the reference-standard method, was conducted in 20 consecutive patients routinely referred at a teaching hospital. Using conservative assumptions, the authors performed cost-effectiveness analysis. RESULTS Power Doppler imaging produced diagnostic-quality images in 89% of patients. When the images of the patients with nondiagnostic examinations were regarded as positive, power Doppler imaging had an area under the receiver operating characteristic curve, A(z), of 0.87, sensitivity of 70%, and specificity of 91%. The validation study results were very similar. The cost-effectiveness of screening and, as indicated, duplex Doppler imaging as the definitive diagnostic examination and endarterectomy was $47,000 per quality-adjusted life-year. CONCLUSION The A(z) value for power Doppler imaging compares well with that for mammography, a generally accepted screening examination, and with most other imaging examinations. Power Doppler imaging is likely to be a reasonably accurate and cost-effective screening examination for carotid artery stenosis in asymptomatic populations.