Volumetric analysis: Rethinking brain metastases response assessment

Abstract

Background The Response Assessment in Neuro-Oncology for Brain Metastases (RANO-BM) criteria are the gold standard for assessing brain metastases (BMs) treatment response. However, they are limited by their reliance on one dimension, despite the routine use of high-resolution T1-weighted MRI scans for BMs, which allows for 3D measurements. Our study aimed to investigate whether volumetric measurements could improve the response assessment in patients with BMs. Methods We retrospectively evaluated a dataset comprising 783 BMs and analyzed the response of 185 of them from 132 patients who underwent stereotactic radiotherapy between 2007 and 2021 at five hospitals. We used T1-weighted MRIs to compute the volume of the lesions. For the volumetric criteria, progressive disease was defined as at least a 30% increase in volume, and partial response was characterized by a 20% volume reduction. Results Our study showed that the proposed volumetric criteria outperformed the RANO-BM criteria in several aspects: 1) Evaluating every lesion, while RANO-BM failed to evaluate 9.2% of them. 2) Classifying response effectively in 140 lesions, compared to only 72 lesions classified by RANO-BM. 3) Identifying BM recurrences a median of 3.3 months earlier than RANO-BM criteria. Conclusion Our study demonstrates the superiority of volumetric criteria in improving the response assessment of BMs compared to the RANO-BM criteria. Our proposed criteria allow for evaluation of every lesion, regardless of its size or shape, better classification, and enable earlier identification of progressive disease. Volumetric criteria provide a standardized, reliable, and objective tool for assessing treatment response.

Prediction of radiologic outcome-optimized dose plans and post-treatment magnetic resonance images: A proof-of-concept study in breast cancer brain metastases treated with stereotactic radiosurgery

“…Net change in contrast-enhancement ΔΔT1w trended negative with increasing RT dose ( Fig. 3 (f)), consistent with RANO-BM criteria [49] , [50] , [51] . ΔFLAIR and ΔT2w also trended negative with increasing dose ( Fig.…”

“…S6 e and Supplementary Table 2 ). Increase in ADC [15] , [16] and decrease in contrast enhancement [49] , [50] , [51] are associated with tumor response to cytotoxic therapies. The inverse model predicts that a progressively higher RT dose distribution to the GTV is required for hypothetical moderate tumor control (moderate ADC and partial suppression of contrast enhancement) through hypothetical aggressive tumor control (high ADC and no contrast enhancement), indicating that the model has “learned” physiologically meaningful relationships between RT dose and post-RT changes on mpMRI ( Supplementary Fig.…”