Automatic registration of DCE-MRI prostate images for follow-up comparison

Analysis of contrast agent uptake using Dynamic Contrast Enhanced MRI (DCE-MRI) might help to distinguish between different tissue types and benign and malign tissue state. It can be applied to localize primary or recurrent prostate cancer. After therapeutic intervention, e.g. radiotherapy, potential recurrences need to be detected as early as possible. A follow-up examination and comparison of contrast agent dynamics in the prostate before and after radiotherapy can provide insight into tumor progression. This paper presents a workflow and a suitable software application which support follow-up analysis of DCE-MRI prostate images before and after radiotherapy. Its main focus lies on automatic rigid image registration to calculate a transformation between the follow-up image and the baseline image. A set of 16 registration results was rated independently by three radiologists. After registration two-dimensional ROIs defined on the baseline image can be transferred to the follow-up image using the determined transformation rule. The presented approach allows for evaluation of corresponding ROIs without altering the original DCE-MRI data of both data sets.