Relationship between vascular enhancement, cerebral hemodynamics, and MR angiography in cases of acute stroke

BACKGROUND AND PURPOSE: The use of MR angiography and contrast-enhanced T1- weighted MR imaging in cases of acute cerebral ischemia may be helpful in t he evaluation of middle cerebral artery (MCA) occlusion and leptomeningeal collaterals, respectively. The aim of our work was to investigate the relat ionship between MCA occlusion, T1-weighted vascular contrast enhancement, h emodynamic alterations, and tissue damage in cases of acute ischemic stroke . METHODS: We studied the MCA territory in 15 patients with acute ischemic st roke within 8 hr of symptom onset, The first MR imaging study (<8 hr after onset) comprised diffusion-weighted imaging, MR angiography, perfusion-weig hted imaging, and contrast-enhanced T1-weighted MR imaging sequences. Follo w-up MR imaging, performed 1 week later, consisted of MR angiography and T2 -weighted fluid-attenuated inversion recovery MR imaging. RESULTS: Early MR angiography showed RICA stem occlusion in nine of 15 pati ents. Patients with MCA occlusion had significantly larger areas of abnorma lity on early diffusion-weighted images, significantly larger areas of alte red hemodynamics, larger final lesion volumes, and poorer clinical outcome. Among the nine patients with MCA stem occlusion, vascular enhancement was marked in seven and absent in two who had complete MCA infarcts and poor cl inical outcome. Among patients with MCA patency, vascular enhancement was m arked in only one, mild in four, and absent in one, Patients with marked va scular enhancement had significantly larger regions of altered hemodynamics and significantly higher asymmetries in both regional cerebral blood volum e and mean transit time because of increased values in the affected hemisph ere. CONCLUSION: Among patients with stroke with MCA occlusion, marked vascular enhancement and increased blood volume indicate efficient leptomeningeal co llaterals and compensatory hemodynamic mechanisms.