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Statistical imaging atlases allow for integration of information from multiple patient studies collected across
different image scales and modalities, such as multi-parametric (MP) MRI and histology, providing population
statistics regarding a specific pathology within a single canonical representation. Such atlases are particularly
valuable in the identification and validation of meaningful imaging signatures for disease characterization in vivo
within a population. Despite the high incidence of prostate cancer, an imaging atlas focused on different anatomic
structures of the prostate, i.e. an anatomic atlas, has yet to be constructed. In this work we introduce a novel
framework for MRI atlas construction that uses an iterative, anatomically constrained registration (AnCoR)
scheme to enable the proper alignment of the prostate (Pr) and central gland (CG) boundaries. Our current
implementation uses endorectal, 1.5T or 3T, T2-weighted MRI from 51 patients with biopsy confirmed cancer;
however, the prostate atlas is seamlessly extensible to include additional MRI parameters. In our cohort, radical
prostatectomy is performed following MP-MR image acquisition; thus ground truth annotations for prostate
cancer are available from the histological specimens. Once mapped onto MP-MRI through elastic registration
of histological slices to corresponding T2-w MRI slices, the annotations are utilized by the AnCoR framework
to characterize the 3D statistical distribution of cancer per anatomic structure. Such distributions are useful for
guiding biopsies toward regions of higher cancer likelihood and understanding imaging profiles for disease extent
in vivo. We evaluate our approach via the Dice similarity coefficient (DSC) for different anatomic structures
(delineated by expert radiologists): Pr, CG and peripheral zone (PZ). The AnCoR-based atlas had a CG DSC of
90.36%, and Pr DSC of 89.37%. Moreover, we evaluated the deviation of anatomic landmarks, the urethra and
veromontanum, and found 3.64 mm and respectively 4.31 mm. Alternative strategies that use only the T2-w
MRI or the prostate surface to drive the registration were implemented as comparative approaches. The AnCoR
framework outperformed the alternative strategies by providing the lowest landmark deviations.
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