Assessment of Brain Tumor Response to Radiotherapy Using Noninvasive Spectroscopic Magnetic Resonance Imaging Techniques

BACKGROUND AND AIM: Brain tumors remain a major clinical challenge, particularly in assessing treatment response after radiotherapy. The aim of this study was to evaluate the effectiveness of noninvasive spectroscopic MRI techniques in monitoring brain tumor response to radiotherapy by analyzing longitudinal changes in metabolic biomarkers. METHOD: This observational longitudinal study was conducted from October 1, 2024, to June 1, 2025, in Erbil, Iraq, using purposive sampling. Patients with primary brain tumors who underwent postoperative radiotherapy at Awat Center were included, with MRI and 3D ^1H-magnetic resonance spectroscopy scans performed at Bawan Diagnostic Center at pretreatment, post-treatment, and follow-up stages. Key biomarkers (choline, creatine, N-acetylaspartate, and lactate) and their ratios were analyzed using repeated measures analysis of variance, Bonferroni post hoc tests, receiver operating characteristic analysis, and multivariate logistic regression. Statistical analysis was performed using Stata version 12 (StataCorp LLC, College Station, TX). RESULTS: A total of 16 patients were included in the study. The most significant biomarker change was a reduction in choline, indicating decreased tumor proliferation across time points. Lactate-to-creatine ratios also declined, reflecting reduced anaerobic metabolism. Receiver operating characteristic analysis identified choline and lactate reductions as the most predictive indicators of treatment response. The final regression model showed that higher Karnofsky Performance Status was significantly associated with better treatment outcomes. Biomarker-driven risk stratification further supported clinical decision making by identifying thresholds for continued therapy versus reassessment. CONCLUSIONS: Noninvasive spectroscopic MRI techniques proved effective in detecting metabolic changes in brain tumors after radiotherapy, especially reductions in choline and lactate, which were associated with clinical treatment response. Based on these findings, policymakers and healthcare providers are encouraged to integrate magnetic resonance spectroscopy into routine neuro-oncology imaging protocols and support specialized training for radiologists.