{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,21]],"date-time":"2026-08-21T13:38:37Z","timestamp":1787319517254,"version":"build-2736575974"},"reference-count":19,"publisher":"MDPI AG","issue":"14","license":[{"start":{"date-parts":[[2021,7,16]],"date-time":"2021-07-16T00:00:00Z","timestamp":1626393600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Cancers"],"abstract":"<jats:p>Purpose: To evaluate urethral contours from two optimized urethral MRI sequences with an MR-guided radiotherapy system (MRgRT). Methods: Eleven prostate cancer patients were scanned on a MRgRT system using optimized urethral 3D HASTE and 3D TSE. A resident radiation oncologist contoured the prostatic urethra on the patients\u2019 planning CT, diagnostic 3T T2w MRI, and both urethral MRIs. An attending radiation oncologist reviewed\/edited the resident\u2019s contours and additionally contoured the prostatic urethra on the clinical planning MRgRT MRI (bSSFP). For each image, the resident radiation oncologist, attending radiation oncologist, and a senior medical physicist qualitatively scored the prostatic urethra visibility. Using MRgRT 3D HASTE-based contouring workflow as baseline, prostatic urethra contours drawn on CT, diagnostic MRI, clinical bSSFP and 3D TSE were evaluated relative to the contour on 3D HASTE using 95th percentile Hausdorff distance (HD95), mean-distance-to-agreement (MDA), and DICE coefficient. Additionally, prostatic urethra contrast-to-noise-ratios (CNR) were calculated for all images. Results: For two out of three observers, the urethra visibility score for 3D HASTE was significantly higher than CT, and clinical bSSFP, but was not significantly different from diagnostic MRI. The mean HD95\/MDA\/DICE values were 11.35 \u00b1 3.55 mm\/5.77 \u00b1 2.69 mm\/0.07 \u00b1 0.08 for CT, 7.62 \u00b1 2.75 mm\/3.83 \u00b1 1.47 mm\/0.12 \u00b1 0.10 for CT + diagnostic MRI, 5.49 \u00b1 2.32 mm\/2.18 \u00b1 1.19 mm\/0.35 \u00b1 0.19 for 3D TSE, and 6.34 \u00b1 2.89 mm\/2.65 \u00b1 1.31 mm\/0.21 \u00b1 0.12 for clinical bSSFP. The CNR for 3D HASTE was significantly higher than CT, diagnostic MRI, and clinical bSSFP, but was not significantly different from 3D TSE. Conclusion: The urethra\u2019s visibility scores showed optimized urethral MRgRT 3D HASTE was superior to the other tested methodologies. The prostatic urethra contours demonstrated significant variability from different imaging and workflows. Urethra contouring uncertainty introduced by cross-modality registration and sub-optimal imaging contrast may lead to significant treatment degradation when urethral sparing is implemented to minimize genitourinary toxicity.<\/jats:p>","DOI":"10.3390\/cancers13143564","type":"journal-article","created":{"date-parts":[[2021,7,16]],"date-time":"2021-07-16T10:52:58Z","timestamp":1626432778000},"page":"3564","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":20,"title":["Evaluation of T2-Weighted MRI for Visualization and Sparing of Urethra with MR-Guided Radiation Therapy (MRgRT) On-Board MRI"],"prefix":"10.3390","volume":"13","author":[{"given":"Jonathan","family":"Pham","sequence":"first","affiliation":[{"name":"Physics and Biology in Medicine IDP, University of California, 650 Charles E Young Drive S, Los Angeles, CA 90095, USA"},{"name":"Department of Radiation Oncology, University of California, 200 Medical Plaza Driveway, Los Angeles, CA 90095, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ricky R.","family":"Savjani","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology, University of California, 200 Medical Plaza Driveway, Los Angeles, CA 90095, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yu","family":"Gao","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology, University of California, 200 Medical Plaza Driveway, Los Angeles, CA 90095, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Minsong","family":"Cao","sequence":"additional","affiliation":[{"name":"Physics and Biology in Medicine IDP, University of California, 650 Charles E Young Drive S, Los Angeles, CA 90095, USA"},{"name":"Department of Radiation Oncology, University of California, 200 Medical Plaza Driveway, Los Angeles, CA 90095, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Peng","family":"Hu","sequence":"additional","affiliation":[{"name":"Physics and Biology in Medicine IDP, University of California, 650 Charles E Young Drive S, Los Angeles, CA 90095, USA"},{"name":"Department of Radiology, University of California, 300 Medical Plaza Driveway, Los Angeles, CA 90095, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ke","family":"Sheng","sequence":"additional","affiliation":[{"name":"Physics and Biology in Medicine IDP, University of California, 650 Charles E Young Drive S, Los Angeles, CA 90095, USA"},{"name":"Department of Radiation Oncology, University of California, 200 Medical Plaza Driveway, Los Angeles, CA 90095, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Daniel A.","family":"Low","sequence":"additional","affiliation":[{"name":"Physics and Biology in Medicine IDP, University of California, 650 Charles E Young Drive S, Los Angeles, CA 90095, USA"},{"name":"Department of Radiation Oncology, University of California, 200 Medical Plaza Driveway, Los Angeles, CA 90095, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Michael","family":"Steinberg","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology, University of California, 200 Medical Plaza Driveway, Los Angeles, CA 90095, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Amar U.","family":"Kishan","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology, University of California, 200 Medical Plaza Driveway, Los Angeles, CA 90095, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yingli","family":"Yang","sequence":"additional","affiliation":[{"name":"Physics and Biology in Medicine IDP, University of California, 650 Charles E Young Drive S, Los Angeles, CA 90095, USA"},{"name":"Department of Radiation Oncology, University of California, 200 Medical Plaza Driveway, Los Angeles, CA 90095, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2021,7,16]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1531","DOI":"10.1016\/S1470-2045(19)30569-8","article-title":"Intensity-modulated fractionated radiotherapy versus stereotactic body radiotherapy for prostate cancer (PACE-B): Acute toxicity findings from an international, randomised, open-label, phase 3, non-inferiority trial","volume":"20","author":"Brand","year":"2019","journal-title":"Lancet Oncol."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"e188006","DOI":"10.1001\/jamanetworkopen.2018.8006","article-title":"Long-term Outcomes of Stereotactic Body Radiotherapy for Low-Risk and Intermediate-Risk Prostate Cancer","volume":"2","author":"Kishan","year":"2019","journal-title":"JAMA Netw. 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Histology, Male Urethra, StatPearls Publishing."}],"container-title":["Cancers"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-6694\/13\/14\/3564\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T06:31:25Z","timestamp":1760164285000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-6694\/13\/14\/3564"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,7,16]]},"references-count":19,"journal-issue":{"issue":"14","published-online":{"date-parts":[[2021,7]]}},"alternative-id":["cancers13143564"],"URL":"https:\/\/doi.org\/10.3390\/cancers13143564","relation":{},"ISSN":["2072-6694"],"issn-type":[{"value":"2072-6694","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,7,16]]}}}