1. A method for operating a computing system to generate a brain tissue viability map from an input image dataset acquired from a patient's brain by a medical imaging system, comprising: computing, for each of one or more different perfusion parameters, an imaged perfusion map of perfusion values as a function of the input image dataset; identifying a normal brain reference region as a function of at least one of the one or more imaged perfusion maps; identifying, for each perfusion parameter, a normal perfusion value as a function of perfusion values in the normal brain reference region; computing, for each perfusion parameter, a normalized perfusion map as a function of the imaged perfusion map and the normal perfusion value; storing linguistic tissue classification rules characterizing each of a plurality of tissue viability classes as a function of one or more of the one or more perfusion parameters; classifying elements of the input image dataset into one of the plurality of tissue viability classes as a function of the one or more normalized perfusion maps and the tissue classification rules; and generating a brain tissue viability map as a function of the classified elements of the input image dataset.