Simultaneous MRI diffusion and perfusion imaging for tumor delineation in prostate cancer patients

Background and purpose: A study was performed to investigate if we can quantify if the two imaging modalities diffusion weighted imaging (DWI) and dynamic contrast-enhanced (DCE)-MRI are consistent in what voxels they determine as being suspicious of tumor tissue. Material and methods: Twenty-one patients with biopsy proven prostate cancer underwent a DWI and a DCE-MRI scan. These scans were compared using a receiver operating curve (ROC) analysis, where either one of the two imaging modalities was thresholded and taken as a reference. The resulting area under the curve (AUC) reflects the consistency between target delineations based on the two imaging techniques. This analysis was performed for the complete prostate and the peripheral zone (PZ). Results: Consistency between DWI and DCE-MRI parameter maps varied greatly between patients. Values of the AUC up to 0.90 were found. However, on average AUC values were 0.60. The AUC values were related to the patient's PSA and clinical stage. Conclusions: Large variation in consistency between the two imaging modalities was found. This did not depend on the precise thresholds used. For making decisions on dose painting in the prostate, the knowledge about the inconsistency must be taken into account.