Determination of focal ischemic lesion volume in the rat brain using multispectral analysis

Multispectral (MS) analysis was used to determine the ischemic lesion volum e in the rat brain after permanent middle cerebral arterial occlusion. MS a nalysis used a four-dimensional MS model consisting of an estimate of the a verage apparent diffusion coefficient of water (ADC(av)), T2, proton densit y, and perfusion. Four classification methods were investigated: (a) multiv ariate gaussian (MVG); (b) k-nearest neighbor (k-NN); (c) k-means (KM); and (d) fuzzy c-means (FCM). MVG and k-NN classifiers are supervised methods r equiring labeled training data to characterize the stroke lesion. Unsupervi sed classifiers (KM, FCM) do not require previous statistics or labeled tra ining data, resulting in potentially greater clinical usefulness. All MS me thods provided significant correlation with postmortem findings beyond the use of ADC(av), alone (partial correlation given the ADC(av) estimate: MVG, .66; k-NN, .75; HM, .68; FCM, .70). This study demonstrates that MS analys is provides an improved estimate of ischemic lesion volume over that obtain ed from ADC alone.