The following is a summary of “MRI-based ventilation and perfusion imaging to predict radiation-induced pneumonitis in lung tumor patients at a 0.35 T MR-Linac,” published in the August 2024 issue of Oncology by Klaar et al.
Radiation-induced pneumonitis (RP) is a common and significant complication arising 6–12 weeks following radiotherapy for lung tumors, and existing clinical and dosimetric parameters have proven insufficient in predicting this adverse effect reliably. This study explores the potential of using non-contrast-enhanced magnetic resonance imaging (MRI) to derive functional parameters throughout the treatment course for enhanced patient stratification and follow-up.
About 23 patients with lung tumors underwent MR-guided hypofractionated stereotactic body radiation therapy using a 0.35 T MR-Linac. Functional ventilation and perfusion maps were generated from 2D cine MRI scans acquired after the first and final fractions of treatment using non-uniform Fourier decomposition. Researchers assessed the relative changes in ventilation and perfusion between the initial and final fractions across three distinct regions: the planning target volume (PTV), the lung volume receiving more than 20 Gy (V20) excluding the PTV, and the whole tumor-bearing lung excluding the PTV. Additionally, the study group compared these functional parameters with three dosimetric metrics: mean lung dose, V20, and the mean dose to the gross tumor volume. Univariate receiver operating characteristic curve analysis (ROC-AUC) was performed with 5,000 bootstrapping samples to evaluate the predictive value of these parameters for RP grade 1. Statistical significance between patients with RP and non-RP was determined using the non-parametric Mann–Whitney U test (α = 0.05).
Of the 23 patients, 14 (60.9%) developed RP grade 1 within three months. Dosimetric parameters did not reveal significant differences between patients who developed RP and those who did not. However, functional MRI parameters, particularly the relative difference in ventilation within the PTV, demonstrated significant predictive potential with a p-value < 0.05 and an AUC of 0.84.
The study highlights that MRI-based functional parameters derived from 2D cine MRI scans are promising predictors of RP in patients with lung tumors. These functional metrics provide valuable insights that could enhance patient stratification and monitoring, potentially improving the management and outcomes of radiotherapy for lung cancer.
Source: sciencedirect.com/science/article/abs/pii/S0167814024007382
