The mid-M1 segment of the middle cerebral artery is a cutoff clot location for good outcome in intravenous thrombolysis.

BACKGROUND AND PURPOSE: We studied the impact of the location of the thrombus (internal carotid artery, proximal M1 segment, distal M1 segment, M2 segment, and M3 segment of the middle cerebral artery) in predicting the clinical outcome of patients treated with intravenous thrombolytic therapy (<3 h) in a retrospective cohort. METHODS: Anterior circulation thrombus was detected with computed tomography angiography in 105 patients. Baseline clinical and radiological information was collected and entered into logistic regression analysis to predict favorable clinical outcome (3-month modified Rankin Scale from 0 to 2 was a primary outcome measure). RESULTS: Three months after stroke, there was a significant increase in mortality (32% vs. 3%, P < 0.001) and functional dependency (82% vs. 29%, P < 0.001) in patients with internal carotid artery or proximal M1 segment of the middle cerebral artery thrombus compared to a more distal occlusion. In the regression analysis, after adjusting for National Institutes of Health Stroke Scale, age, sex, and onset-to-treatment time, the clot location was an independent predictor of good clinical outcome (P = 0.001) and exhibited dose-response type behavior when moving from a proximal vessel position to a more distal one. When the location was dichotomized, a cutoff between the proximal and the distal M1 segments best differentiated between good and poor clinical outcome (OR = 16.0, 95% CI 3.9-66.2). CONCLUSIONS: The outcome of acute internal carotid artery or proximal M1 segment of the middle cerebral artery occlusion is generally poor even if treated with intravenous thrombolysis. Alternative revascularization strategies should be considered. Vascular imaging at the admission is required to guide this decision.

Contrast enhancement of round atelectases.

PURPOSE: To find out if round atelectases (RAs) of a lung enhance more than pulmonary malignant tumors. MATERIAL AND METHODS: Twelve patients with RA and 16 patients with malignant lung tumor (MLT) evidenced on CT examination were selected (14 RAs and 16 MLTs). Two patients had 2 RAs. The examination data were reviewed on a work station and the attenuation values of RAs and tumors were measured. RESULTS: At enhanced CT the density of RAs varied from 88 to 190 HU whereas for MLTs the density varied from 30 to 71 HU. The difference between attenuation values of RAs and MLTs was statistically significant. CONCLUSION: The attenuation values of RAs after contrast enhancement seem to differ from those of MLTs, at least during the first minute after contrast injection, and thus serve as a useful aid in the differential diagnosis of these masses.