PMID- 38300388 OWN - NLM STAT- MEDLINE DCOM- 20240329 LR - 20240331 IS - 1573-7373 (Electronic) IS - 0167-594X (Print) IS - 0167-594X (Linking) VI - 167 IP - 1 DP - 2024 Mar TI - Evaluating contouring accuracy and dosimetry impact of current MRI-guided adaptive radiation therapy for brain metastases: a retrospective study. PG - 123-132 LID - 10.1007/s11060-024-04583-9 [doi] AB - BACKGROUND: Magnetic resonance imaging (MRI) guided adaptive radiotherapy (MRgART) has gained increasing attention, showing clinical advantages over conventional radiotherapy. However, there are concerns regarding online target delineation and modification accuracy. In our study, we aimed to investigate the accuracy of brain metastases (BMs) contouring and its impact on dosimetry in 1.5 T MRI-guided online adaptive fractionated stereotactic radiotherapy (FSRT). METHODS: Eighteen patients with 64 BMs were retrospectively evaluated. Pre-treatment 3.0 T MRI scans (gadolinium contrast-enhanced T1w, T1c) and initial 1.5 T MR-Linac scans (non-enhanced online-T1, T2, and FLAIR) were used for gross target volume (GTV) contouring. Five radiation oncologists independently contoured GTVs on pre-treatment T1c and initial online-T1, T2, and FLAIR images. We assessed intra-observer and inter-observer variations and analysed the dosimetry impact through treatment planning based on GTVs generated by online MRI, simulating the current online adaptive radiotherapy practice. RESULTS: The average Dice Similarity Coefficient (DSC) for inter-observer comparison were 0.79, 0.54, 0.59, and 0.64 for pre-treatment T1c, online-T1, T2, and FLAIR, respectively. Inter-observer variations were significantly smaller for the 3.0 T pre-treatment T1c than for the contrast-free online 1.5 T MR scans (P < 0.001). Compared to the T1c contours, the average DSC index of intra-observer contouring was 0.52‒0.55 for online MRIs. For BMs larger than 3 cm(3), visible on all image sets, the average DSC indices were 0.69, 0.71 and 0.64 for online-T1, T2, and FLAIR, respectively, compared to the pre-treatment T1c contour. For BMs < 3 cm(3), the average visibility rates were 22.3%, 41.3%, and 51.8% for online-T1, T2, and FLAIR, respectively. Simulated adaptive planning showed an average prescription dose coverage of 63.4‒66.9% when evaluated by ground truth planning target volumes (PTVs) generated on pre-treatment T1c, reducing it from over 99% coverage by PTVs generated on online MRIs. CONCLUSIONS: The accuracy of online target contouring was unsatisfactory for the current MRI-guided online adaptive FSRT. Small lesions had poor visibility on 1.5 T non-contrast-enhanced MR-Linac images. Contour inaccuracies caused a one-third drop in prescription dose coverage for the target volume. Future studies should explore the feasibility of contrast agent administration during daily treatment in MRI-guided online adaptive FSRT procedures. CI - (c) 2024. The Author(s). FAU - Wang, Bin AU - Wang B AD - Department of Radiation Oncology, State Key Laboratory of Oncology in South China, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-Sen University Cancer Center, 651 East Dongfeng Road, Guangzhou, Guangdong, 510060, People's Republic of China. FAU - Liu, Yimei AU - Liu Y AD - Department of Radiation Oncology, State Key Laboratory of Oncology in South China, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-Sen University Cancer Center, 651 East Dongfeng Road, Guangzhou, Guangdong, 510060, People's Republic of China. FAU - Zhang, Jun AU - Zhang J AD - Department of Radiation Oncology, State Key Laboratory of Oncology in South China, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-Sen University Cancer Center, 651 East Dongfeng Road, Guangzhou, Guangdong, 510060, People's Republic of China. FAU - Yin, Shaohan AU - Yin S AD - Department of Radiology, State Key Laboratory of Oncology in South China, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-Sen University Cancer Center, Guangzhou, 510060, People's Republic of China. FAU - Liu, Biaoshui AU - Liu B AD - Department of Radiation Oncology, State Key Laboratory of Oncology in South China, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-Sen University Cancer Center, 651 East Dongfeng Road, Guangzhou, Guangdong, 510060, People's Republic of China. FAU - Ding, Shouliang AU - Ding S AD - Department of Radiation Oncology, State Key Laboratory of Oncology in South China, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-Sen University Cancer Center, 651 East Dongfeng Road, Guangzhou, Guangdong, 510060, People's Republic of China. FAU - Qiu, Bo AU - Qiu B AD - Department of Radiation Oncology, State Key Laboratory of Oncology in South China, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-Sen University Cancer Center, 651 East Dongfeng Road, Guangzhou, Guangdong, 510060, People's Republic of China. qiubo@sysucc.org.cn. FAU - Deng, Xiaowu AU - Deng X AD - Department of Radiation Oncology, State Key Laboratory of Oncology in South China, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-Sen University Cancer Center, 651 East Dongfeng Road, Guangzhou, Guangdong, 510060, People's Republic of China. dengxw@sysucc.org.cn. LA - eng GR - 2022YXWL0201/Special Research Fund for Medical Physics and Technologies by Guangdong Biomedical Engineering Society of China/ GR - 2022YFC2402300/National Key R&D Program of China/ GR - 202206010154/Science and Technology Program of Guangzhou, China/ PT - Journal Article DEP - 20240201 PL - United States TA - J Neurooncol JT - Journal of neuro-oncology JID - 8309335 SB - IM MH - Humans MH - Retrospective Studies MH - Radiotherapy Planning, Computer-Assisted/methods MH - Magnetic Resonance Imaging/methods MH - *Radiosurgery MH - *Brain Neoplasms/diagnostic imaging/radiotherapy PMC - PMC10978730 OTO - NOTNLM OT - Adaptive radiotherapy (ART) OT - Brain metastases OT - Fractionated stereotactic radiotherapy (FSRT) OT - MR-Linac OT - MR-guided adaptive radiotherapy (MRgART) OT - Target contouring COIS- The authors declare no competing interests. EDAT- 2024/02/01 12:42 MHDA- 2024/03/29 06:46 PMCR- 2024/02/01 CRDT- 2024/02/01 11:13 PHST- 2023/12/27 00:00 [received] PHST- 2024/01/22 00:00 [accepted] PHST- 2024/03/29 06:46 [medline] PHST- 2024/02/01 12:42 [pubmed] PHST- 2024/02/01 11:13 [entrez] PHST- 2024/02/01 00:00 [pmc-release] AID - 10.1007/s11060-024-04583-9 [pii] AID - 4583 [pii] AID - 10.1007/s11060-024-04583-9 [doi] PST - ppublish SO - J Neurooncol. 2024 Mar;167(1):123-132. doi: 10.1007/s11060-024-04583-9. Epub 2024 Feb 1.