Can Diffusion-Perfusion Mismatch on Brain MRI in Acute Ischemic Stroke Patients Predict Clinical Outcome?: Preliminary Study Focused on rCBV

ABSTRACT

BACKGROUND: Diffusion-perfusion mismatch (DPM) on MRI has been considered an ischemic penumbra. However, several reports have demonstrated limitation of DPM on MRI as a predictable marker of the ischemic penumbra. In this study, we investigated the relationship between DPM and the clinical progression in acute ischemic stroke patients. METHODS: We consecutively recruited fifty-seven patients showing acute ischemic stroke (within 24 hours) in the middle cerebral artery (MCA) territory. The clinical outcomes were determined by serial measurement of National Institute of Health Stroke Scale (NIHSS) and modified Rankin Scale (mRS) during 30 days after their ischemic event. We also evaluated the relationship among the parameters of perfusion MRI and the clinical worsening in patients with DPM on initial MRI. RESULTS: Nineteen (33.3%) patients had DPM on MRI within 24 hours after stroke onset. Even though the frequency of clinical worsening for 30 days after stroke onset was higher in DPM group (26%) than in non-DPM group (11%), it did not reach statistical significance (p=0.143). However, extent of MCA stenosis (p<0.001) and time to peak (TTP) delay on MRI (p<0.001) were significantly greater in patients with DPM than in those without DPM. Among several parameters of the perfusion MRI, only relative cerebral blood volume (rCBV) was significantly related to the clinical worsening (62.9+/-24.7% vs 96.1+/-19.2%, p=0.007) in patients with DPM. CONCLUSIONS: This study shows that DPM on MRI does not always predict the clinical worsening in acute ischemic stroke. To overcome this problem, we should analyze rCBV map based DPM as well as TTP map based DPM.