Findings of Perfusion MR Imaging in Acute Middle Cerebral Artery Territory Ischemic Stroke

ABSTRACT

BACKGROUND: Although a magnetic resonance imaging (MRI) is highly sensitive for changes associated with ischemic stroke, the detection of an acute ischemic lesion is usually impossible within 6 hours of the stroke onset on a conventional MRI. The perfusion MRI is a new imaging technique for diagnosing acute ischemic stroke. We evaluate the clinical usefulness of the perfusion MRI in predicting the final infarct extent in 18 patients with acute middle cerebral artery (MCA) territory ischemic stroke. METHOD: The perfusion MRI was performed within 6 hours after the stroke onset in all patients with a single-section dynamic contrast-enhanced T2*-weighted imaging in conjunction with a conventional routine MRI and MR angiography. Time-concentration curves and cerebral blood volume (CBV) maps were calculated from the dynamic MR imaging data by using numerical integration techniques. We compared findings of CBV maps with infarction on a follow-up CT or MRI. RESULTS: In 14 of 18 patients, the CBV in the occluded MCA territory were decreased. In the remaining 4 patients with a reversible ischemic neurologic deficit (RIND) or transient ischemic attack (TIA), the CBV were increased in 3 and normal in 1. Out of 14 patients with a decreased CBV, two had focal regions of increased CBV within the affected territory, indicating reperfusion hyperemia. The regions of increased or decreased CBV were eventually converted to infarction on follow-up images in all 14 patients. Out of 4 patients with RIND or TIA, one showed focal infarction in centrum semiovale on a follow-up image. CONCLUSIONS: The perfusion MRI was useful for the assessment of hemodynamic change about cerebral perfusion and may predict the extent of final infarction in acute MCA territory ischemic stroke. These results suggest that the perfusion MRI may play an important role in the diagnosis and management of acute ischemic stroke.