Objectives: Multi-parametric MRI is emerging as a promising method for prostate cancer diagnosis. prognosis and
treatment planning. However, the localization of in-vivo detected lesions and pathologic sites of cancer remains a
significant challenge. To overcome this limitation we have developed and tested a system for co-registration of in-vivo
MRI, ex-vivo MRI and histology.
Materials and Methods: Three men diagnosed with localized prostate cancer (ages 54-72, PSA levels 5.1-7.7 ng/ml)
were prospectively enrolled in this study. All patients underwent 3T multi-parametric MRI that included T2W, DCEMRI,
and DWI prior to robotic-assisted prostatectomy. Ex-vivo multi-parametric MRI was performed on fresh prostate
specimen. Excised prostates were then sliced at regular intervals and photographed both before and after fixation. Slices
were perpendicular to the main axis of the posterior capsule, i.e., along the direction of the rectal wall. Guided by the
location of the urethra, 2D digital images were assembled into 3D models. Cancer foci, extra-capsular extensions and
zonal margins were delineated by the pathologist and included in 3D histology data. A locally-developed software was
applied to register in-vivo, ex-vivo and histology using an over-determined set of anatomical landmarks placed in
anterior fibro-muscular stroma, central. transition and peripheral zones. The mean root square distance across
corresponding control points was used to assess co-registration error.
Results: Two specimens were pT3a and one pT2b (negative margin) at pathology. The software successfully fused invivo
MRI. ex-vivo MRI fresh specimen and histology using appropriate (rigid and affine) transformation models with
mean square error of 1.59 mm. Coregistration accuracy was confirmed by multi-modality viewing using operator-guided
Conclusion: The method enables successful co-registration of pre-operative MRI, ex-vivo MRI and pathology and it
provides initial evidence of feasibility of MRI-guided surgical planning.