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Progression of middle cerebral artery susceptibility sign on T2*-weighted images: its effect on recanalization and clinical outcome after thrombolysis.

Kim HS, Lee DH, Choi CG, Kim SJ, Suh DC

Department of Radiology, Division of Neuroradiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, 388-1 Poongnap-dong, Songpa-gu, Seoul 138-736, South Korea.

OBJECTIVE: The middle cerebral artery (MCA) "susceptibility sign" on T2*-weighted imaging has been reported to indicate acute thrombotic occlusion. We evaluated the serial progression of this susceptibility sign on follow-up MRI and its effect on recanalization and clinical outcome after intraarterial thrombolysis. MATERIALS AND METHODS: Thirty-three acute ischemic stroke patients who were treated with intraarterial thrombolysis and underwent MRI within 6 hours of symptom onset were enrolled in this study. All study participants had either M1 or M2 occlusion on digital subtraction angiography before thrombolysis and underwent follow-up MRI 2-3 days after thrombolysis. Recanalization status was evaluated using the thrombolysis in myocardial infarction (TIMI) flow grade on digital subtraction angiography immediately after thrombolysis. The serial progression of the susceptibility sign on follow-up T2*-weighted imaging was compared with the MR angiographic findings. Baseline clinical parameters and clinical outcome were also reviewed. RESULTS: A positive MCA susceptibility sign on the initial T2*-weighted imaging was detected in 16 (48%) of the 33 patients. The mean TIMI grade was higher in the patients with a positive sign on imaging than in those without the sign (2.3 vs 1.0, respectively; p < 0.005). In the risk factor analysis, a history of atrial fibrillation was significantly higher in the patients with the MCA susceptibility sign than in those with negative findings for the sign (13/16 [81%] vs 4/17 [24%], respectively). In 14 of the 16 patients with the positive sign, the sign disappeared on follow-up MRI, and that finding (i.e., disappearance of the sign) was well correlated with complete recanalization on follow-up MR angiography in 12 patients. Multivariate logistic regression analysis showed that this sign was not associated with a favorable functional outcome 30 days after thrombolytic treatment. CONCLUSION: The MCA susceptibility sign can be indicative of acute thromboembolic occlusion and can be used to predict the immediate effectiveness of intraarterial thrombolysis. However, the appearance of this sign was not associated with a favorable clinical outcome after thrombolysis in our small series study.

Published 20 November 2006 in AJR Am J Roentgenol, 187(6): W650-7.
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