Validation of MRI to TRUS registration for HDR prostate brachytherapy

TitleValidation of MRI to TRUS registration for HDR prostate brachytherapy
Publication TypeJournal Article
Year of PublicationIn Press
AuthorsPoulin, E., Boudam K., Pinter C., Kadoury S., Lasso A., Fichtinger G., & Menard C.

Purpose: The objective of this study was to develop and
validate an open-source module for MRI to transrectal ultrasound (TRUS)
registration to support tumor-targeted prostate brachytherapy.

Methods and Materials: In this study, fifteen patients with prostate
cancer lesions visible on multiparametric MRI were selected for the
validation. T2-weighted images with 1 mm isotropic voxel size and
diffusion weighted images were acquired on a 1.5T Siemens. Three
dimensional (3D) TRUS images with 0.5 mm slice thickness were acquired.
The investigated registration module was incorporated in the open-source
3D Slicer platform and can compute rigid and deformable transformations.
An extension of 3D Slicer, SlicerRT, allows import and export to DICOM-RT
formats. For validation, similarity indices, prostate volumes and
centroid positions were determined in addition to registration errors for
common 3D points identified by an experienced radiation oncologist.

Results: The average time to compute the registration was 35±3 seconds.
For the deformable and rigid registration respectively, Dice similarity
coefficients were 0.93±0.01 and 0.87±0.05 while the 95% Hausdorff
distance was 2.2±0.3 and 4.2±1.0 mm. MRI volumes obtained after the rigid
and deformable registration were not statistically different (p>0.05)
from reference TRUS volumes. For the deformable and rigid registration
respectively, 3D distance error between centroid positions were 0.4±0.1
and 2.1±1.0 mm while registration errors between common points were
2.3±1.1 and 3.5±3.2 mm. Deformable registration was found significantly
better (p<0.05) than rigid registration in all parameters.

Conclusions: An open-source MRI to TRUS registration platform was
validated for integration in the brachytherapy workflow.

PerkWeb Citation KeyPoulin2017b
Refereed DesignationRefereed