Prostate cancer tumor grade differentiation with dynamic contrast-enhancedMR imaging in the rat: Comparison of macromolecular and small-molecular contrast media - Preliminary experience

PURPOSE: To differentiate prostate cancers of different histopathologic gra des with dynamic gadolinium-enhanced magnetic resonance (MR) imaging. Resul ts with a conventional small-molecular contrast medium (CM) were compared t o those with a prototypic macromolecular CM. MATERIALS AND METHODS: High- and low-grade tumors, sublines of the Dunning R3327 rat prostate cancer line, were subcutaneously implanted into the flan ks of 12 male Copenhagen rats. Dynamic contrast material-enhanced MR imagin g was performed with small-molecular CM and macromolecular CM at an interva l of 1 day. Microvascular permeability, as estimated with the endothelial t ransfer coefficient, and fractional plasma volume were calculated for each tumor and each CM by means of a two-compartmental, bidirectional kinetic mo del. RESULTS: Mean endothelial transfer coefficient values for both macromolecul ar CM and small-molecular CM were significantly different between the two t umor sublines: (P =.0004 and P = 01, respectively). For the high- and low-g rade tumors, no overlap of values was seen with macromolecular CM, but a br oad overlap was seen with small-molecular CM despite a significant differen ce in mean values. CONCLUSION: Dynamic contrast-enhanced MR imaging permits differentiation of histopathologic prostatic tumor types. Quantitative microvascular permeabi lity characteristics estimated from macromolecular CM-enhanced data were:si gnificantly superior to those derived from small-molecular CM-enhanced data .