Response assessment of stereotactic body radiation therapy using dynamic contrast‐enhanced integrated MR‐PET in non‐small cell lung cancer patients

Purpose To evaluate the response in patients undergoing SBRT using dynamic contrast‐enhanced (DCE) integrated magnetic resonance positron emission tomography (MR‐PET). Stereotactic body radiation therapy (SBRT) is efficacious as a front‐line local treatment for non‐small cell lung cancer (NSCLC). Materials and Methods We prospectively enrolled 19 lung tumors in 17 nonmetastatic NSCLC patients who were receiving SBRT as a primary treatment. They underwent DCE‐integrated 3T MR‐PET before and 6 weeks after SBRT. The following image parameters were analyzed: tumor size, standardized uptake value (SUV), apparent diffusion coefficient, Ktrans, kep, ve, vp, and iAUC60. Chest computed tomography (CT) was performed at 3 months after SBRT. Results SBRT treatment led to tumor changes including significant decreases in the SUVmax (–61%, P < 0.001), Ktrans mean (–72%, P = 0.005), Ktrans standard deviation (SD; –85%, P = 0.046), kep mean (–53%, P = 0.014), kep SD (–63%, P = 0.001), and vp SD (–58%, P = 0.002). The PET SUVmax was correlated with the MR kep mean (P = 0.002) and kep SD (P < 0.001). The percentage reduction in Ktrans mean (P < 0.001) and kep mean (P = 0.034) at 6 weeks post‐SBRT were significantly correlated with the percentage reduction in tumor size, as measured using CT at 3 months after SBRT. Univariate analyses revealed a trend toward disease progression when the initial SUVmax > 10 (P = 0.083). Conclusion In patients with NSCLC who are receiving SBRT, DCE‐integrated MR‐PET can be used to evaluate the response after SBRT and to predict the local treatment outcome. Level of Evidence: 2 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2018;47:191–199.