Metabolism of DWI Lesions: Implications for Rescue Therapy

Minor stroke with total mismatch after acute MCA occlusion

BACKGROUND

Recently, "total mismatch," negative diffusion-weighted imaging (DWI) and extensive perfusion defects were introduced and described as having a favorable outcome after intravenous thrombolysis. We sought to determine the clinical characteristics of patients with total mismatch and describe their clinical courses.

METHODS

We retrospectively analyzed subjects from the stroke registry of acute ischemic stroke patients between August 2008 and October 2009. The patients with the following characteristics were included: acute ischemic stroke within 6 hours of symptom onset, a large artery occlusion in the anterior circulation and a negative DWI but large perfusion-weighted imaging (PWI) lesion on mean transit time maps. According to our stroke imaging protocol, the patients underwent emergent MR imaging immediately after admission and follow-up imaging within 96 hours of symptom onset.

RESULTS

Four patients were identified as suitable for the imaging criteria (negative DWI and MTT delay) of this study. All patients presented with a spontaneous recovery of ischemic symptoms related to the middle cerebral artery occlusion had a potential source of cardioembolism and eventually developed new lesions on follow-up DWI and recanalization without thrombolysis.

CONCLUSION

In our study, total mismatch seems to suggest favorable outcome after recanalization, regardless of thrombolysis. Further attention should be focused on the considerable variations in PWI and DWI findings in acute stroke.

Total mismatch: negative diffusion-weighted imaging but extensive perfusion defect in acute stroke

BACKGROUND AND PURPOSE

The perfusion-weighted imaging (PWI)/diffusion-weighted imaging (DWI) mismatch may identify patients who benefit from thrombolysis. However, some patients exhibit a "total mismatch," ie, negative DWI but extensive PWI defect. We aimed to assess clinical and MRI data of these patients.

METHODS

From June 2007 to December 2008, patients with anterior circulation ischemic stroke were evaluated for a "total mismatch" profile. MRI was performed at admission and at day 1. The score was assessed at baseline and the modified Rankin scale score was assessed at day 30.

RESULTS

Among 52 patients, 3 showed a total mismatch with arterial occlusion confirmed on magnetic resonance angiography. All had fluctuating symptoms (National Institutes of Health Stroke Scale scores, 0 to 10) and received intravenous tissue plasminogen activator. Day 1 DWI disclosed minimal changes in all patients. Outcome was favorable in all patients (day 30 modified Rankin scale, 0-1).

CONCLUSION

PWI may be helpful for treatment decisions in patients without DWI damage and fluctuating clinical course.