Arnaldo Mayer1,2, Adi Zholkover3, Orith Portnoy3,4, Gil Raviv4,5, Eli Konen3,4, Zvi Symon4,6. 1. Diagnostic Imaging Institute, Sheba Medical Center, Ramat Gan, Israel. arnmayer@gmail.com. 2. Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel. arnmayer@gmail.com. 3. Diagnostic Imaging Institute, Sheba Medical Center, Ramat Gan, Israel. 4. Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel. 5. Department of Urology, Sheba Medical Center, Ramat Gan, Israel. 6. Department of Radiation Oncology, Sheba Medical Center, Ramat Gan, Israel.
Abstract
PURPOSE: Focal therapy in low-risk prostate cancer may provide the best balance between cancer control and quality of life preservation. As a minimally invasive approach performed under TRUS guidance, brachytherapy is an appealing framework for focal therapy. However, the contrast in TRUS images is generally insufficient to distinguish the target lesion from normal prostate tissue. MRI usually offers a much better contrast between the lesion and surrounding tissues. Registration between TRUS and MRI may therefore significantly improve lesion targeting capability in focal prostate brachytherapy. In this paper, we present a deformable registration framework for the accurate fusion of TRUS and MRI prostate volumes under large deformations arising from dissimilarities in diameter, shape and orientation between endorectal coils and TRUS probes. METHODS: Following pose correction by a RANSAC implementation of the ICP algorithm, TRUS and MRI Prostate contour points are represented by a 3D extension of the shape-context descriptor and matched by the Hungarian algorithm. Eventually, a smooth free-form warping is computed by fitting a 3D B-spline mesh to the set of matched points. RESULTS: Quantitative validation of the registration accuracy is provided on a retrospective set of ten real cases, using as landmarks either brachytherapy seeds (six cases) or external beam radiotherapy fiducials (four cases) implanted and visible in both modalities. The average registration error between the landmarks was 2.49 and 3.20 mm, for the brachytherapy and external beam sets, respectively, that is less than the MRI voxels' long axis length ([Formula: see text]). The overall average registration error (for brachytherapy and external beam datasets together) was 2.56 mm. CONCLUSIONS: The proposed method provides a promising framework for TRUS-MRI registration in focal prostate brachytherapy.
PURPOSE: Focal therapy in low-risk prostate cancer may provide the best balance between cancer control and quality of life preservation. As a minimally invasive approach performed under TRUS guidance, brachytherapy is an appealing framework for focal therapy. However, the contrast in TRUS images is generally insufficient to distinguish the target lesion from normal prostate tissue. MRI usually offers a much better contrast between the lesion and surrounding tissues. Registration between TRUS and MRI may therefore significantly improve lesion targeting capability in focal prostate brachytherapy. In this paper, we present a deformable registration framework for the accurate fusion of TRUS and MRI prostate volumes under large deformations arising from dissimilarities in diameter, shape and orientation between endorectal coils and TRUS probes. METHODS: Following pose correction by a RANSAC implementation of the ICP algorithm, TRUS and MRI Prostate contour points are represented by a 3D extension of the shape-context descriptor and matched by the Hungarian algorithm. Eventually, a smooth free-form warping is computed by fitting a 3D B-spline mesh to the set of matched points. RESULTS: Quantitative validation of the registration accuracy is provided on a retrospective set of ten real cases, using as landmarks either brachytherapy seeds (six cases) or external beam radiotherapy fiducials (four cases) implanted and visible in both modalities. The average registration error between the landmarks was 2.49 and 3.20 mm, for the brachytherapy and external beam sets, respectively, that is less than the MRI voxels' long axis length ([Formula: see text]). The overall average registration error (for brachytherapy and external beam datasets together) was 2.56 mm. CONCLUSIONS: The proposed method provides a promising framework for TRUS-MRI registration in focal prostate brachytherapy.
Authors: Robert C Susil; Kevin Camphausen; Peter Choyke; Elliot R McVeigh; Gary S Gustafson; Holly Ning; Robert W Miller; Ergin Atalar; C Norman Coleman; Cynthia Ménard Journal: Magn Reson Med Date: 2004-09 Impact factor: 4.668
Authors: Christopher W Smith; Ryan Alfano; Douglas Hoover; Kathleen Surry; David D'Souza; Jonathan Thiessen; Irina Rachinsky; John Butler; Jose A Gomez; Mena Gaed; Madeleine Moussa; Joseph Chin; Stephen Pautler; Glenn S Bauman; Aaron D Ward Journal: Phys Imaging Radiat Oncol Date: 2021-07-30