the endothelial integrity of microvessels is disturbed in malignant tumors . we invented a method wherein we used mri to define tumor microvascular permeabilities and correlated these permeabilities with histologic grade in tumors . using macromolecular mri contrast medium , we discovered tumor microvascular permeability values were significantly lower in benign tumors than in carcinomas . in addition , we found that the microvascular permeability values demonstrated a strong correlation with the histologic grade of carcinomas as determined by the scarff - bloom - richardson grading system .