Clinical Implications of Power Doppler Three-Dimensional Ultrasonography

Abstract

Power Doppler ultrasonography displays an estimate of the entire power contained in that part of the received radiofrequency ultrasound signal for which a phase shift corresponding to the motion of the target is detected. In contrast, conventional color Doppler imaging displays Doppler frequency shift information. Few reports have been published on the clinical utility of three-dimensional power Doppler ultrasonography in vascular patients. This study analyzed our experience of the clinical utility of this technology. Fifty-three patients selected out of 281 who were referred to our vascular laboratory underwent both conventional color duplex ultrasonography and power Doppler ultrasonography for the following indications: the question of subtotal versus total arterial occlusion, tortuous artery with limited imaging on color duplex ultrasonography, the presence of significant disease by Doppler ultrasonography with limited imaging, deep-lying arteries with an obscure orifice (e.g., renal artery), and heavily calcified arteries. The power Doppler ultrasonography portion of the examination was considered of positive diagnostic value if the final impression was different from that of conventional color duplex ultrasonography. A positive diagnostic value was achieved in 22 of 29 (76%) carotid artery examinations, 10 of 14 (71%) peripheral artery examinations, 4 of 5 (80%) renal artery examinations, and 3 of 5 (60%) aortoiliac examinations. Overall, positive diagnostic value was achieved by adding power Doppler ultrasonography in 39 of 53 patients (74%). Five of six patients (83%) who were felt to have carotid occlusion by color duplex ultrasonography were confirmed to have subtotal occlusion by power Doppler ultrasonography. Similarly, 6 of 8 patients (75%) with questionable subtotal versus total peripheral arterial occlusion by color duplex ultrasonography were confirmed to have subtotal occlusion by power Doppler ultrasonography. Four of five patients' (80%) renal examinations had a positive diagnostic value, which included three patients in whom the orifice of renal arteries was not seen by color duplex ultrasonography. Three-dimensional power Doppler ultrasonography can be more readily applied to clinical practice. Power Doppler ultrasonography is capable of defining the severity or extent of vascular disease, particularly in differentiating subtotal from total arterial occlusion.