Ischemic Findings of T2*-Weighted 3-Tesla MRI in Acute Stroke Patients

Abstract

Background: We compared ischemic findings on gradient echo-type T₂*-weighted images at 3-tesla MRI (T₂*WI) in patients with acute ischemia and major vessel occlusion, and stroke patients with lacunar infarction or branch atheromatous disease. Methods: Our study population consisted of 45 patients with acute stroke. They underwent 3-tesla MRI within 12 h of stroke onset. Included were 24 patients (13 men and 11 women, mean age 68 years) with major vessel occlusion and 21 patients (11 men and 10 women, mean age 69 years) with minor infarction such as lacunar infarcts or branch atheromatous disease. We classified vascular ischemic findings of T₂*WI into 3 sign categories, i.e. artery susceptibility sign, cortical vessel sign (hypointensity and enlargement of the cortical vessels) and brush sign (hypointensity of vessels in the deep white matter). Decreased intensity in the ischemic parenchyma was designated ischemic tissue sign. We compared regions of interest in the hypoperfused area on flow-sensitive alternating inversion recovery (FAIR) images with our vascular ischemic findings. Results: None of the vascular ischemic signs nor the ischemic tissue sign were found in patients with minor vessel disease. All 24 patients with major vessel occlusion manifested the cortical vessel sign, 23 the brush sign. The area with ischemic vessel signs on T₂*WI was almost as large or somewhat smaller than the hypoperfused area on FAIR images. Compared to the contralateral side, 14 of 24 patients (58.3%) with major vessel occlusion showed decreased intensity in the ischemic parenchyma (ischemic tissue sign). Region of interest measurements on FAIR images demonstrated greater hypoperfusion in the area classified as ischemic tissue sign on T₂*WI. Conclusions: Ischemic vessel signs and the ischemic tissue sign on T₂*WI at 3 T would be useful to evaluate the extensive ischemia due to major vessel occlusion and may be correlated with the blood-oxygen-level-dependent effect due to increased deoxyhemoglobin. The ischemic tissue sign may be reflective of severe ischemia.