Trans-cytolemmal water exchange in prostate manifest via DCE-MRI

To investigate the potential of the unidirectional cellular water efflux rate constant (k_io) from DCE-MRI data in prostate MR imaging.

High-temporal-resolution prostate DCE-MRI data were modeled using both the fast-exchange-limit (FXL) Tofts' model as well as the water-exchange-sensitized shutter-speed model (SSM). In the SSM, k_io was included as an additional fitting parameter. Lesion and normal-appearing (NA) prostate tissue region-of-interest (ROI) data were analyzed and categorized into FXL or non-FXL conditions based on results from the two models. A global upper limit of k_io detectable by prostate DCE-MRI with the SSM was presented.

While many lesion voxels exhibited sensitivity to k_io with the SSM, a substantial portion remained in the FXL condition despite greater contrast agent extravasation than in NA tissue. The fraction of FXL voxels was higher in lesions than in NA tissue. Applying a global detectable k_io upper limit increased the difference between lesion and NA ROIs, improving lesion characterization.

SSM-derived FXL and non-FXL contrasts may serve as novel imaging biomarkers for prostate cancer surveillance. Advances in MRI technology and more potent contrast agents are expected to enhance the accuracy of k_io quantification, potentially enabling its integration into clinical mpMRI.