POWER DOPPLER IMAGING OF CAROTID-ARTERY STENOSIS - COMPARISON WITH COLOR DOPPLER FLOW IMAGING AND ANGIOGRAPHY

Background and Purpose Power Doppler imaging (PDI) is a new sonographi c technique that has recently been introduced for vascular application . Since the technical principles of PDI may provide increased sensitiv ity to visualize the continuity of blood flow in arterial stenoses, we investigated the diagnostic significance of PDI and the intermethod r elationship for the measurement and classification of internal carotid artery (ICA) stenosis in comparison with both color Doppler flow imag ing (CDFI) and angiography. Methods One hundred patients with a total of 128 ICA stenoses (50% to 69%, n=37; 70% to 79%, n=27; 80% to 99%, n =64) and 12 ICA occlusions were consecutively investigated by means of PDI, CDFI, and intra-arterial angiography (n=48). Reduction of the in trastenotic lumen was measured on longitudinal and transverse views of PDI and CDFI for the calculation of the degree of diameter and area s tenosis, respectively. Angiographic stenosis was determined with the u se of the North American Symptomatic Carotid Endarterectomy Trial (NAS CET), European Carotid Surgery Trial (ECST), and common carotid (CC) m ethods. Results PDI provided significantly more excellent or good (92% versus 79%; P<.01) displays of the intrastenotic lumen than CDFI, par ticularly in complicated high-grade stenosis. While linear regression analysis demonstrated a high overall correlation between PDI and CDFI for diameter (r=.88; P<.001) and area stenosis (r=.79 P<.001), categor ization of ICA stenosis revealed best agreement for 80% to 99% area st enoses. Since angiography frequently either underclassified (NASCET me thod) or overclassified (ECST, CC methods) the degree of ICA stenosis in comparison to both PDI and CDFI, the sonographic-angiographic corre lation was only moderate (regression coefficients ranged from .62 to . 70; P<.001). Conclusions PDI further improves the assessment of ICA st enosis by providing better visualization of the stenotic vascular lume n than CDFI. Sonographic imaging of the stenotic plaque on both PDI an d CDFI provided a direct measurement of the local degree of stenosis, while the angiographic grade of stenosis essentially depended on the m ethod used for evaluation.