Clinical usefulness of and problems with three-dimensional CT angiography for the evaluation of arteriosclerotic stenosis of the carotid artery: Comparison with conventional angiography, MRA, and ultrasound sonography

BACKGROUND Prevention of stroke is aided by determination of the degree of carotid artery stenosis and progression of arterial sclerosis. Three-dimens ional computed tomography (CT) angiography (SD-CTA) is a new method for eva luating the degree of arterial stenosis. The purpose of this study was to c ompare the accuracy of 3D-CTA with the "gold standard": conventional angiog raphy, magnetic resonance angiography (MRA), and ultrasound sonography (US) . METHODS A total of 128 carotid bifurcations in 64 patients (42 men and 22 w omen; mean age, 68.5 years) were examined by 3D-CTA because of symptoms of cerebral infarction, carotid bruit, or findings suggestive of arteriosclero tic carotid artery stenosis on MRA screening. The following were used to co mpare 3D-CTA with conventional angiography, MRA and US: 1) estimation of th e degree of stenosis; 2) depiction of irregularities in arterial walls, inc luding calcification, intimal thickening, ulcers and plaque; and 3) surgica l planning for carotid endarterectomy (CEA) and percutaneous transluminal a ngioplasty (PTA), and postoperative evaluation. RESULTS A strong correlation was found between the degrees of stenosis esti mated by conventional angiography and 3D-CTA MIP image (r = 0.987/p < 0.000 1). On the other hand, stenosis was generally overestimated by MRA, which, however, has the advantage of being able to scan the carotid siphon to the middle cerebral artery at one time. Calcification and ulceration of the art ery wall could be evaluated with 3D-CTA, whereas with US, progression of ar terial sclerosis could be evaluated by differentiation of homogenous and he terogenous plaque. The anatomical relationships between the site of stenosi s and the internal jugular vein and bony structures, which must be known be fore CEA, were confirmed by observation of rotated images using the shaded surface reconstruction (SSR) method. Because the hemodynamics of cross and collateral flows cannot be clearly imaged with 3D-CTA, standard angiography is needed to determine suitability for bypass surgery, CONCLUSIONS The current method used in our hospital for the diagnosis of st enosis of the internal carotid artery includes MRA or US for initial screen ing, 3D-CTA for evaluation of the degree of stenosis and for preoperative a nd postoperative evaluation of CEA and PTA, and conventional angiography fo r evaluation of hemodynamics and determination of the indications for a byp ass surgery. (C) 1999 by Elsevier Science Inc.