CT angiography in the evaluation of acute stroke.

PURPOSE To determine the worth of CT angiography of the circle of Willis as a supplement to routine CT in the examination of patients with symptoms of acute stroke in terms of its depiction of the number and distribution of arterial stenoses or occlusions. We also sought to compare the accuracy of CT angiography with MR angiography and/or digital subtraction angiography (DSA). METHODS One hundred forty-five patients with symptoms of acute stroke were examined with routine head CT and CT angiography of the circle of Willis. MR angiography was also performed in 27 patients and DSA in 28 patients. CT and MR angiograms and DSAs were reviewed for stenoses or occlusions involving the vessels about the circle of Willis. MR and CT angiograms were also evaluated for image quality, and the corresponding routine CT and MR studies were evaluated for the presence of arterial infarction. RESULTS CT angiograms were rated good or excellent in 89% of cases whereas MR angiograms were rated good or excellent in 92% of cases. Arterial stenoses or occlusions were present on 43% of CT angiograms, 48% of MR angiograms, and 21% of DSAs. Findings were in agreement in 98% of the vessels analyzed by CT angiography and MR angiography. Similarly, there was overall agreement of findings in 99% of vessels analyzed by CT angiography and DSA. None of the patients had any immediate adverse reactions after administration of intravenous nonionic iodinated contrast material. CONCLUSION CT angiography is an accurate and safe method for evaluating arterial stenoses or occlusions in the vessels about the circle of Willis. CT angiography should be used in patients with symptoms of acute stroke for whom evaluation of the intracranial vasculature is desirable.