A dimensionless dynamic contrast enhanced MRI parameter for intra-prostatic tumour target volume delineation: Initial comparison with histology

摘要

Purpose: T2 weighted and diffusion weighted magnetic resonance imaging (MRI) show promise in isolating prostate tumours. Dynamic contrast enhanced (DCE)-MRI has also been employed as a component in multi-parametric tumour detection schemes. Model-based parameters such as K~(trans) are conventionally used to characterize DCE images and require arterial contrast agent (CR) concentration. A robust parameter map that does not depend on arterial input may be more useful for target volume delineation. We present a dimensionless parameter (W_(io)) that characterizes CR wash-in and washout rates without requiring arterial CR concentration. W_(io) is compared to K~(trans) in terms of ability to discriminate cancer in the prostate, as demonstrated via comparison with histology. Methods: Three subjects underwent DCE-MRI using gadolinium contrast and 7 s imaging temporal resolution. A pathologist identified cancer on whole-mount histology specimens, and slides were deformably registered to MR images. The ability of W_(io) maps to discriminate cancer was determined through receiver operating characteristic curve (ROC) analysis. Results: There is a trend that W_(io) shows greater area under the ROC curve (AUC) than K~(trans) with median AUC values of 0.74 and 0.69 respectively, but the difference was not statistically significant based on a Wilcoxon signed-rank test (p =0.13). Conclusions: Preliminary results indicate that W_(io) shows potential as a tool for K~(trans) QA, showing similar ability to discriminate cancer in the prostate as K~(trans) without requiring arterial CR concentration.