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.