Validation of functional imaging with pathology for tumor delineation in the prostate

Introduction: A study was performed to validate magnetic resonance (MR) based prostate tumor delineations with pathology. Material and methods: Five patients with biopsy proven prostate cancer underwent a T2 weighted (T2w), diffusion weighted MRI (DW-MRI) and dynamic contrast-enhanced MRI (DCE-MRI) scan before prostatectomy. Suspicious regions were delineated based on all available MR information. After prostatectomy whole-mount hematoxylin-eosin stained (H&E) sections were made. Tumor tissue was delineated on the H&E stained sections and compared with the MR based delineations. The registration accuracy between the MR images and H&E stained sections was estimated. Results: A tumor coverage of 44-89% was reached by the MR based tumor delineations. The application of a margin of ∼5 mm to the MR based tumor delineations yielded a tumor coverage of 85-100% in all patients. Errors created during the registration procedure were 2-3 mm, which cannot completely explain the limited tumor coverage. Conclusions: An accurate tissue processing and registration method was presented (registration error 2-3 mm), which enables the validation of MR based tumor delineations with pathology. Reasonable tumor coverage of about 85% and larger was found when applying a margin of ∼5 mm to the MR based tumor delineations.