Usefulness of Three-dimensional CT Angiography (3D-CTA) for the Evaluation of Carotid Artery Stenosis

Helical CT scanning is a new technique that can continuously generate a volume of data. The data thus aquired with contrast medium is reconstructed for three-dimensional CT angiography (3D-CTA), including 3D-angiographic image using the volume rendering method, 2D-MIP image using maximum intensity projection method and 3D-endoscopic image using the surface rendering method.Nineteen cervical carotid artery stenoses in II patients were studied with 3D-CTA. Nine lesions in 7 patients of these cases underwent carotid endarterectomy (CEA). These 3D-CTA findings were compared qualitatively to DSA (digital subtraction angiography) findings and endarterectomy specimens.3D-angiographic image clearly visualizes severe stenosis and occlusion of carotid artery without calcification. Carotid artery stenosis with extensive calcification is not always demonstrated such as the stenotic change of the carotid artery. 3D-endoscopic image shows vessel lumen and the inner surface of plaque bulgings and strictures, simulating angioscope. But this image is also modified by calcification. Therefore, an MIP image is useful to detect calcification in the stenotic lesion. A superimposed image of angiographic image and MIP image or endoscopic image and MIP image is more useful.Although this technique requires further development and clinical evaluation, 3D-CTA is very valuable for the evaluation of carotid artery stenosis.