Anatomy of stroke, Part I - An MRI-based topographic and volumetric system of analysis

Background and Purpose-The clinical diagnosis and treatment of stroke, as well as investigations into the underlying pathophysiology of the disease, hinge on inferences from the anatomy of the stroke lesion. We describe an MRI-based system of topographic and volumetric analysis that considers distribution of infarct with respect to neuroanatomic structures, superficial and deep perfusion compartments, and gray and white matter tissue types. Methods-MRI-based 3-dimensional topographic and volumetric analysis of presumed MCA embolic stroke was performed months after the acute event in 21 subjects ranging in age from 34 to 75 years. Results-The topography of infarction was greatly variable, with virtually all regions of the MCA territory involved in at least I stroke in the series. In 14, there was involvement of the M I as well as the M2 through M4 territories; in 6, there was involvement of only the M2 through M4 territories; and in 2, there was involvement of only the M1 territory. The volumes varied from 3.1 to 256 cm(3), corresponding approximately to a range of 1% to 90% of the total MCA territory. Conclusions-The system of topographic and volumetric analysis is generally applicable to all strokes in the forebrain where the infarct is visualized in MRI, independent of vascular territory, clinical correlates, and interval between stroke and MRI. The results emphasize the variety of topographic patterns and lesion volumes of strokes. Intended long-range applications include correlation of outcome of stroke with predictions from acute-phase diffusion-. and perfusion-weighted imaging and investigations of the potential benefit of therapeutic agents.