title: Imaging of prostate cancer: a platform for 3D co-registration of in-vivo MRI ex-vivo MRI and pathology.
abstract: OBJECTIVE
  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.
  
  
  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, DCE-MRI, 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 in-vivo 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 variable transparency.
  
  
  CONCLUSIONS
  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.
authors.affiliation: University Hospital of Caen, Avenue de la Côte de Nacre, Caen FRANCE 14033 ; New York University Medical Center. 550 1 Avenue, New York NY USA 10016.
authors.forename: Clement
authors.initials: C
authors.lastname: Orczyk
authors.affiliation: New York University Medical Center. 550 1 Avenue, New York NY USA 10016.
authors.forename: Artem
authors.initials: A
authors.lastname: Mikheev
authors.affiliation: New York University Medical Center. 550 1 Avenue, New York NY USA 10016.
authors.forename: Andrew B
authors.initials: AB
authors.lastname: Rosenkrantz
authors.affiliation: New York University Medical Center. 550 1 Avenue, New York NY USA 10016.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Melamed
authors.affiliation: New York University Medical Center. 550 1 Avenue, New York NY USA 10016.
authors.forename: Samir S
authors.initials: SS
authors.lastname: Taneja
authors.affiliation: New York University Medical Center. 550 1 Avenue, New York NY USA 10016.
authors.forename: Henry
authors.initials: H
authors.lastname: Rusinek
keywords: MRI; co-registration; focal therapy; histology; human studies; prostate cancer; surgical planning