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(Stroke. 2009;40:3130.)
© 2009 American Heart Association, Inc.

Research Letters

M1 Susceptibility Vessel Sign on T2* as a Strong Predictor for No Early Recanalization After IV-t-PA in Acute Ischemic Stroke

Kazumi Kimura, MD; Yasuyuki Iguchi, MD; Kensaku Shibazaki, MD; Masao Watanabe, MD; Takeshi Iwanaga, MD Junya Aoki, MD

From the Department of Stroke Medicine, Kawasaki Medical School, Japan.

Correspondence to Dr K. Kimura, Department of Stroke Medicine, Kawasaki Medical School, 577 Matsushima, Kurashiki City, Okayama 701-0192, Japan. E-mail kimurak{at}med.kawasaki-m.ac.jp

Background and Purpose— In acute stroke patients treated with intravenous tissue plasminogen activator (t-PA), early recanalization of occluded arteries can improve the clinical outcome. The magnetic susceptibility effect of deoxygenated hemoglobin in red thrombi can present as hypointense signals on T2*-weighted gradient echo imaging. We investigated whether the gradient echo imaging M1 susceptibility vessel sign (M1 SVS) can predict no early recanalization after t-PA infusion.

Methods— Patients with internal carotid artery and M1 occlusion were prospectively studied. MRI studies, including DWI, T2*, and MRA, were performed before and within 30 minutes and 24 hours after t-PA infusion. The NIHSS score was obtained before and 7 days after t-PA administration. The relationship between the presence of the M1 SVS and no early recanalization and patient outcome was examined.

Results— A total of 48 patients (29 men; mean age, 74.6±11.2 years) were enrolled. M1 SVS was present in 13 (27.1%) patients and absent in 35 (72.9%) patients. There were no significant differences in clinical characteristics between the 2 groups. Follow-up MRA within 30 minutes after t-PA infusion revealed that 20 (57.1%) of the 35 patients without the M1 SVS had early recanalization, but that none of the 13 patients with the M1 SVS had early recanalization (P=0.0002). Seven days after t-PA infusion, dramatic improvement was more frequently observed in patients without the M1 SVS (51.4%) than in those with the M1 SVS (0%, P=0.0007).

Conclusion— The M1 SVS on T2* appears to be a strong predictor for no early recanalization after t-PA therapy.

Key Words: T2* recanalization • tissue plasminogen activator • outcome