Map‐ISODATA demarcates regional response to combination rt‐PA and 7E3 F(ab′)2 treatment of embolic stroke in the rat

Abstract

Purpose: To investigate the ability of map‐ISODATA (Iterative Self‐Organizing Data Analysis Technique) to classify the different categories of ischemic damage in the lesion and to evaluate a combined (thrombolysis plus antiplatelet) treatment efficacy in an embolic stroke of rat.Materials and Methods: Rats subjected to embolic stroke with (N = 12) and without (N = 10) rt‐PA and 7E3 F(ab′)₂ treatment (4 hours after embolization) were followed (at 2, 24, and 48 hours post‐MCAO) with magnetic resonance imaging (MRI) using T₁, T₂, and apparent diffusion coefficient of water (ADCw). ISODATA was computed from T₁, T₂, and ADCw maps. The signatures characterized by the map‐ISODATA were compared with histological quantitative evaluation and were employed to demarcate the specific regions in the lesion.Results: The signature described by map‐ISODATA is highly correlated with the degree of tissue damage in the lesion and can distinguish the severity of ischemic tissue injury. Based upon map‐ISODATA, ischemic lesion area can be divided into three specific regions, each characterized by a distinct evolution of injury and treatment response. The combined treatment significantly reduces the lesion size between 24 and 48 hours and improves the outcome 48 hours post‐MCAO compared with the control group.Conclusion: Map‐ISODATA provides an accurate means to identify lesion area, to distinguish ischemic damage, and to detect treatment response. 7E3 F(ab′)₂ extends the rt‐PA treatment window to at least four hours after the onset of embolic stroke of rat. J. Magn. Reson. Imaging 2005;21:726–734.