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World J Clin Oncol. Oct 24, 2026; 17(10): 124285
Published online Oct 24, 2026. doi: 10.5306/wjco.124285
Contrast-enhanced T2-fluid-attenuated inversion recovery magnetic resonance imaging for radiotherapy target delineation in brain metastases: A narrative review
Yuan-Yuan Li, Zhi-Tao Dai, Hai-Ge Zhang, Yao-Tao Li, Ran Tang, An-Yan Gu, Yu Wu, Su-Yan Bi, Tai-Lun Huang, Li-Xiang Yang, Yin Zhang, Xing-Ru Sun
Yuan-Yuan Li, Zhi-Tao Dai, Yin Zhang, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital and Shenzhen Hospital, Department of Radiation Oncology, Chinese Academy of Medical Sciences and Peking Union Medical College, Shenzhen 518116, Guangdong Province, China
Hai-Ge Zhang, Yao-Tao Li, Ran Tang, An-Yan Gu, Yu Wu, Tai-Lun Huang, Xing-Ru Sun, Department of Radiation Oncology, The Affiliated Huizhou Hospital, Guangzhou Medical University, Huizhou 516001, Guangdong Province, China
Su-Yan Bi, Post-Doctoral Research Center, Department of Radiation Oncology, Yuebei People's Hospital, Southern Medical University, Shaoguan 519001, Guangdong Province, China
Li-Xiang Yang, Department of Radiation Oncology, Philips Health Technology (China) Company, Guangzhou 510116, Guangdong Province, China
Co-corresponding authors: Yin Zhang and Xing-Ru Sun.
Author contributions: Zhang Y and Sun XR contribute equally to this study as co-corresponding authors; Li YY, Zhang Y and Sun XR were responsible for conceptualization, statistical analysis, original draft writing, manuscript review and editing; Dai ZT, Zhang HG, Tang R and Gu AY were responsible for data extraction, statistical analysis; Bi SY and Li YT were responsible for original draft writing and revising; Wu Y, Haung TL and Yang LX were responsible for manuscript review and editing; and all authors contributed to the article and approved the submitted version.
AI contribution statement: No AI tools were used in this manuscript. All authors confirm the full originality of the content and take full responsibility for the work.
Supported by 2025 Annual Cooperation Fund of Cancer Hospital of Chinese Academy of Medical Sciences, No. E030125012.
Conflict-of-interest statement: The authors declare no relationships with any companies, whose products or services may be related to the subject matter of the article.
Corresponding author: Xing-Ru Sun, MD, Professor, Department of Radiation Oncology, The Affiliated Huizhou Hospital, Guangzhou Medical University, No. 1 Xuebei Avenue, Huicheng District, Huizhou 516001, Guangdong Province, China.
18843108845@163.com
Received: June 11, 2026
Revised: August 12, 2026
Accepted: October 8, 2026
Published online: October 24, 2026
Processing time: 134 Days and 0.5 Hours
Brain metastases (BM) are the most common type of brain tumor, with diagnosis, pre-treatment evaluation, and follow-up relying on imaging. Radiotherapy, including whole brain radiotherapy and stereotactic radiosurgery, is a key treatment modality for BM, and its efficacy is closely related to the precision of target delineation, which depends on clear and accurate multimodal imaging. The target delineation for BM is typically performed using a fusion technique combining computed tomography and magnetic resonance imaging (MRI). In routine MRI, contrast-enhanced T1-weighted imaging (T1WI + C) is considered the basic sequence, but it has certain limitations, such as the interference with lesion signals adjacent to large vessels and the cerebral cortex caused by enhanced vascular signals. T2-fluid-attenuated inversion recovery (T2-FLAIR) sequence suppresses the signal of free water [cerebrospinal fluid (CSF)] while highlighting the signal of bound water (intracranial edema). Contrast-enhanced T2-FLAIR (T2-FLAIR + C) sequence further improves visualization, thereby addressing the limitations of T1WI + C. Specifically, T2-FLAIR + C effectively suppresses CSF signals while clearly delineating enhanced lesions, particularly those on the brain surface and adjacent to the cerebral cortex. Additionally, its heightened sensitivity to low concentrations of gadolinium allows for indirect assessment of the vascularity of brain and meningeal tumors. However, the use of MRI simulation in radiotherapy for BM is not widespread, and the application of the T2-FLAIR + C sequence is not yet common. This narrative review elaborates on the technical principles of the T2-FLAIR + C sequence and current guidelines for BM radiotherapy target delineation, summarizes its clinical applications in BM radiotherapy, and discusses existing evidence gaps and future research directions. Notably, direct evidence supporting the benefit of T2-FLAIR + C for contouring accuracy, dosimetric optimization, and patient clinical outcomes remains limited. This review aims to provide a comprehensive reference for further research and clinical application of T2-FLAIR + C in BM radiotherapy.
Core Tip: For brainmetastasis delineation, enhanced T2-fluid-attenuated inversion recovery (T2-FLAIR) sequence can significantly enhance the accuracy of target contouring in condition of low-dose gadolinium-based contrast agents. Simultaneously, in consideration of the heterogeneity inside the tumor enhanced T2-FLAIR sequence can help to provide a more personalized treatment.
