CT after intracranial intraarterial thrombolysis for acute stroke.

PURPOSE To determine the incidence, appearance, and clinical significance of lesions mimicking intraparenchymal hemorrhages on CT in patients treated with intracranial intraarterial thrombolysis for acute strokes. METHODS Ten cases of acute stroke treated with direct intraarterial urokinase infusion were retrospectively reviewed. Clinical and radiographic findings before and after therapy were all evaluated. RESULTS Six (60%) of the 10 patients showed areas of increased attenuation on CT shortly after thrombolytic therapy. The lesions were associated with clinical deterioration in two cases (20%); in these two cases the lesions persisted on CT for several days. The lesions were asymptomatic in two (20%) cases; the lesions cleared on CT within 24 hours in those two patients. In two (20%) patients, immediate clinical improvement was evident despite the radiodense areas. These lesions also cleared within 24 hours. CT Hounsfield unit measurements of four of the lesions revealed very high Hounsfield units in two lesions, only one of which was a symptomatic lesion. MR in two cases revealed residue of hemorrhage. CONCLUSION Intraparenchymal areas of increased attenuation may be seen on the CT scans of patients after intraarterial thrombolysis. The density is often at least partially attributable to contrast extravasation. The lesions should not necessarily be interpreted as hemorrhage alone, especially in the absence of clinical deterioration. Rapid clearing may be a positive prognostic sign.