M Ida1, K Mizunuma, Y Hata, S Tada. 1. Department of Radiology, Jikei University School of Medicine, Tokyo, Japan.
Abstract
PURPOSE: To describe subcortical low intensity on T2- and proton density-weighted MR images in early cortical ischemia and to discuss a cause of these findings. METHODS: Nine patients with early cortical ischemia were studied with proton density- and T2-weighted images, and T1-weighted images at 1.5 T. Gadolinium enhancement was added in six cases. RESULTS: In all cases there was high to intermediate intensity in the cortex and low intensity in the subcortical white matter (subcortex) on the proton density- and T2-weighted images. No significant signal abnormalities were shown on T1-weighted images in the subcortex; gyriform enhancement was seen in the affected cortex in all of the six patients studied with gadolinium. Of the four patients with follow-up MRs, the subcortical low intensity changed to high intensity in two and remained low in two patients in the chronic stage. Neither hemorrhage nor calcification was seen on CT. CONCLUSION: Iron accumulation in the subcortex caused by disruption of the axonal transportation and continuous production of free radicals caused by the hypoxic-ischemic state most likely reduces the signal intensity of the subcortex on the proton density- and T2-weighted images. The subcortical low intensity on the proton density- and T2-weighted images is an important diagnostic sign of early cortical ischemia.
PURPOSE: To describe subcortical low intensity on T2- and proton density-weighted MR images in early cortical ischemia and to discuss a cause of these findings. METHODS: Nine patients with early cortical ischemia were studied with proton density- and T2-weighted images, and T1-weighted images at 1.5 T. Gadolinium enhancement was added in six cases. RESULTS: In all cases there was high to intermediate intensity in the cortex and low intensity in the subcortical white matter (subcortex) on the proton density- and T2-weighted images. No significant signal abnormalities were shown on T1-weighted images in the subcortex; gyriform enhancement was seen in the affected cortex in all of the six patients studied with gadolinium. Of the four patients with follow-up MRs, the subcortical low intensity changed to high intensity in two and remained low in two patients in the chronic stage. Neither hemorrhage nor calcification was seen on CT. CONCLUSION:Iron accumulation in the subcortex caused by disruption of the axonal transportation and continuous production of free radicals caused by the hypoxic-ischemic state most likely reduces the signal intensity of the subcortex on the proton density- and T2-weighted images. The subcortical low intensity on the proton density- and T2-weighted images is an important diagnostic sign of early cortical ischemia.