j landmark $\mathcal{L}^M_j$ on MRI, while X represents the number of landmarks. Similarly, we computed the urethra distances, using per-slice correspondences, and slices where the urethra was visible on both MRI and histopathology slices.

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Results {#results .unnumbered}
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Phantom Study {#phantom-study .unnumbered}
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The phantom study is used to assess the average performance and variability of RAPSODI under conditions known to affect the tissue during the histopathology preparation. We ran our registration approach for 480 different conditions, to estimate the trends of the evaluation metrics as well as to their variations.  \[fig:PhantomResults\] summarizes our results in which we tested the effect of the rotation of histopathology slices while mounting on glass slide (range: 0-40$^\circ$), and the effect of shrinkage (range: 0-30%) when perfect slice correspondences exist between the histopathology and the MRI images in the phantom. Our approach is able to perfectly recover rotation angles ranging between 0-20$^\circ$ or shrinkage of 0-10% when applied alone ( \[fig:PhantomResults\]), indicated by the perfect $\tilde{}$ 1 dice coefficient and the sub-pixel error. When combined, either using 20% shrinkage and random rotation ( \[fig:PhantomResults\]b,f,j) or using 20$^\circ$ rotation and shrinkage ( \[fig:PhantomResults\]d,h,l), 