Semiautomatic registration of digital histopathology images to in vivo MR images in molded and unmolded prostates

Abstract

Purpose To evaluate a semi-automatic software-based method of registering in vivo prostate magnetic resonance (MR) images to digital histopathology images using two approaches: 1) in which the prostates were molded to simulate distortion due to the endorectal imaging coil prior to fixation, and 2) in which the prostates were not molded. Materials and Methods T2-weighted MR images and digitized whole-mount histopathology images were acquired for twenty-six patients with biopsy-confirmed prostate cancer who underwent radical prostatectomy. Ten excised prostates were molded prior to fixation. A semi-automatic method was used to align MR images to histopathology. Percent overlap between MR and histopathology images, as well as distances between corresponding anatomical landmarks were calculated and used to evaluate the registration technique for molded and unmolded cases. Results The software successfully morphed histology-based prostate images into corresponding MR images. Percent overlap improved from 80.4±5.8% prior to morphing to 99.7±0.62% post morphing. Molded prostates had a smaller distance between landmarks (1.91±0.75mm) versus unmolded (2.34±0.68mm), p<0.08. Conclusion Molding a prostate prior to fixation provided a better alignment of internal structures within the prostate, but this did not reach statistical significance. Software-based morphing allowed for nearly complete overlap between the pathology slides and the MR images.

Role of endorectal MR imaging and MR spectroscopic imaging in defining treatable intraprostatic tumor foci in prostate cancer: Quantitative analysis of imaging contour compared to whole-mount histopathology

“…Six of the cases were molded during fixing to replicate the mechanical compression effect of the endorectal probe [17]. Transverse step sections were obtained at 3 mm intervals in a plane perpendicular to the prostatic urethra.…”

Accurate validation of ultrasound imaging of prostate cancer: a review of challenges in registration of imaging and histopathology

“…This procedure requires a three-dimensional in vivo scan to fabricate a tailor-made mould to force the specimen into its in vivo shape during the sectioning process. Moulds can also be used to simulate a transrectal probe pressing against the specimen; however, for MRI, an endorectal-coil mimicking mould did not significantly improve the registration performance [ 55 ]. Obviously, moulding cannot take into account deformations within the prostate and cannot compensate for inhomogeneous shrinkage.…”