Optimizing Lymph Node Metastasis Imaging in MR-Guided Radiotherapy for Oligometastatic Prostate Cancer

Darren M C Poon; Jing Yuan; Minsong Cao; Yingli Yang; Cindy Xue; John P Christodouleas

doi:10.1093/bjr/tqaf142

Optimizing Lymph Node Metastasis Imaging in MR-Guided Radiotherapy for Oligometastatic Prostate Cancer

Br J Radiol. 2025 Jun 23:tqaf142. doi: 10.1093/bjr/tqaf142. Online ahead of print.

Authors

Darren M C Poon¹, Jing Yuan², Minsong Cao³, Yingli Yang^{4

5}, Cindy Xue², John P Christodouleas^{6

7}

Affiliations

¹ Comprehensive Oncology Centre, Hong Kong Sanatorium & Hospital, Happy Valley, Hong Kong SAR, China.
² Research Department, Hong Kong Sanatorium & Hospital, Happy Valley, Hong Kong SAR, China.
³ Department of Radiation Oncology, University of California, Los Angeles, Los Angeles, CA, United States.
⁴ Department of Radiology, Ruijin Hospital, Shanghai Jiaotong Univeristy School of Medicine, Shanghai, China.
⁵ SJTU-Ruijing-UIH Institute for Medical Imaging Technology, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China.
⁶ Elekta AB, Stockholm, Sweden.
⁷ Department of Radiation Oncology, Hospital of the University of Pennsylvania, Philadelphia.

PMID: 40581618
DOI: 10.1093/bjr/tqaf142

Abstract

MR-guided radiotherapy (MRgRT) using MR-LINAC is a critical advancement in prostate cancer (PC) treatment. Leveraging the superior soft tissue contrast of MR imaging (MRI), along with online adaptation capabilities and real-time MRI for advanced motion management, MRgRT has demonstrated efficacy in localized PC irradiation. Recent studies have demonstrated that MRgRT can effectively treat individual lymph node metastasis (LNM), with preliminary results showing excellent patient tolerability and safety as a novel metastasis-directed radiotherapy (MDRT) for oligometastatic PC (omPC). However, current LNM imaging on an MR-LINAC is limited and suboptimal, creating reliance on diagnostic MRI and positron emission tomography (PET) for differentiation, registration, contouring, and adaptation. The inherent uncertainty and errors within these processes impair the accuracy and precision of LNM irradiation in MRgRT. This review aims to provide an overview of the current imaging techniques employed in clinical MRgRT practice for omPC, highlighting the unmet clinical needs due to the limitations of LNM imaging using an MR-LINAC. Furthermore, it reviews promising advanced LNM MRI techniques potentially transferable to MR-LINAC. Lastly, it discusses future developments in LNM imaging on an MR-LINAC and its potential as a comprehensive one-stop imaging solution for future omPC MRgRT.

Keywords: MR-guided-radiotherapy (MRgRT); MRI integrated linear accelerator (MR-LINAC); lymph node metastasis (LNM); metastasis-directed treatment (MDT); oligometastatic prostate cancer (omPC).

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