Registration methods for histological slides and ex vivo MRI of prostate

A methodology for registering histological slides and ex vivo MRI of prostate is proposed. After such registration is performed, spatial correspondence between histology slides and ex vivo MRI is established, thus histological truth can be propagated to the ex vivo MRI space. We employ the well established registration approach based on mutual information (MI) and thin-plate splines (TPS), which is automatic after user´s initial placement of control points. Directly registering histology slides onto ex vivo MRI is challenging because 1) it is a difficult 2D (slice) to 3D (volume) registration problem and 2) there is a big difference in information content as histology slides are typically taken at much higher resolution than ex vivo MRI. Here we propose to overcome this challenge by breaking the difficult direct registration task into easier registration sub-tasks. For this purpose, we acquire digital photographs of prostate specimen as it is sectioned, which are referred to as block face photos. First, we register histology slides onto block face photos and then register block face photos onto ex vivo MRI. Results from two registrations tasks are combined to establish registration between histology slides and ex vivo MRI. Before the second registration task, we stack the block face photos into a volume so that registration onto the ex vivo MRI is a more stable 3D (volume) to 3D (volume) registration.