Deformable current-prior registration of DCE breast MR images on multi-site data

Recent studies indicate that malignant breast lesions can be predicted from structural changes in prior exams of preventive breast MRI examinations. Due to non-rigid deformation between studies, spatial correspondences between structures in two consecutive studies are lost. Thus, deformable image registration can contribute to predicting individual cancer risks. This study evaluates a registration approach based on a novel breast mask segmentation and non-linear image registration based on data from 5 different sites. The landmark error (mean +/- standard deviation [1st quartile, 3rd quartile]), annotated by three radiologists, is 2.9 +/- 2.8 [1.3, 3.2] mm when leaving out two outlier cases from the evaluation for which the registration failed completely. We assess the inter-observer variabilities of keypoint errors and find an error of 3.6 +/- 4.7 [1.6, 4.0] mm, 4.4 +/- 4.9 [1.8, 4.8] mm, and 3.8 +/- 4.0 [1.7, 4.1] mm when comparing each radiologist to the mean keypoints of the other two radiologists. Our study shows that the current state of the art in registration is well suited to recover spatial correspondences of structures in cancerous and non-cancerous cases, despite the high level of difficulty of this task.