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

Abstract

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, K^trans , k_ep , v_e , v_p , 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 SUV_max (-61%, P < 0.001), K^trans mean (-72%, P = 0.005), K^trans standard deviation (SD; -85%, P = 0.046), k_ep mean (-53%, P = 0.014), k_ep SD (-63%, P = 0.001), and v_p SD (-58%, P = 0.002). The PET SUV_max was correlated with the MR k_ep mean (P = 0.002) and k_ep SD (P < 0.001). The percentage reduction in K^trans mean (P < 0.001) and k_ep 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 SUV_max > 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.

Keywords: dynamic contrast-enhanced magnetic resonance; non-small cell lung cancer; positron emission tomography; stereotactic body radiation therapy.