Three-dimensional template combined with MR-guided iodine-125 brachytherapy for recurrent brain metastases

J Contemp Brachytherapy. 2023 Jun;15(3):174-183. doi: 10.5114/jcb.2023.129055. Epub 2023 Jun 30.

Abstract

Purpose: Treatment of recurrent brain metastases is extremely challenging. Here, we evaluated the feasibility and efficacy of an individualized three-dimensional template combined with MR-guided iodine-125 (125I) brachytherapy in the treatment of recurrent brain metastases.

Material and methods: Twenty-eight patients with recurrent 38 brain metastases underwent 125I brachytherapy from December, 2017 to January, 2021. A pre-treatment brachytherapy plan and three-dimensional template were generated according to isovoxel T1-weighted MR images. 125I seeds were implanted under the guidance of three-dimensional template and 1.0-T open MR imaging. Dosimetry verification was performed based on CT/MR fusion images. Pre-operative and post-operative dosimetry parameters of D90, V100, and conformity index (CI) were compared. Overall response rate (ORR), disease control rate (DCR) at 6 months, and 1-year survival rate were calculated. Median overall survival (OS) measured from the date of 125I brachytherapy was estimated using Kaplan-Meier method.

Results: No significant differences were observed between pre-operative and post-operative D90, V100, and CI values (p > 0.05). The ORR and DCR at 6 months were 91.3% and 95.7%, respectively. The 1-year survival rate was 57.1%. The median OS was 14.1 months. Two cases of minor hemorrhage and 5 cases of symptomatic brain edema were observed during the study. All clinical symptoms were alleviated after corticosteroid treatment applied for 7 to 14 days.

Conclusions: A three-dimensional template combined with MR-guided 125I brachytherapy in the treatment of recurrent brain metastases is feasible, safe, and effective. This novel 125I brachytherapy strategy is an attractive alternative in the treatment of brain metastases.

Keywords: brachytherapy; brain metastases; magnetic resonance imaging; printing; three-dimensional.