Combination of 99mTc-Labeled PSMA-SPECT/CT and Diffusion-Weighted MRI in the Prediction of Early Response After Carbon Ion Therapy in Prostate Cancer: A Non-Randomized Prospective Pilot Study

Abstract

Ping Li,1– 3,* Chang Liu,4– 6,* Shuang Wu,2,3,7 Lin Deng,2,3,8 Guangyuan Zhang,2,3,8 Xin Cai,1– 3 Silong Hu,4– 6 Jingyi Cheng,2,3,6,9 Xiaoping Xu,4– 6 Bin Wu,2,3,10 Xiaomao Guo,2,3,7 Yingjian Zhang,4– 6 Shen Fu,5,11 Qing Zhang1– 3 1Department of Radiation Oncology, Shanghai Proton and Heavy Ion Center, Shanghai, People’s Republic of China; 2Shanghai Key Laboratory of Radiation Oncology, Shanghai, People’s Republic of China; 3Shanghai Engineering Research Center of Proton and Heavy ion Radiation Therapy, Shanghai, People’s Republic of China; 4Department of Nuclear Medicine, Fudan University Shanghai Cancer Center, Shanghai, People’s Republic of China; 5Key Laboratory of Nuclear Physics and Ion-Beam Application (MOE), Fudan University, Shanghai, People’s Republic of China; 6Shanghai Engineering Research Center for Molecular Imaging Probes, Shanghai, People’s Republic of China; 7Department of Radiation Oncology, Shanghai Proton and Heavy Ion Center, Fudan University Cancer Hospital, Shanghai, People’s Republic of China; 8Department of Radiology, Shanghai Proton and Heavy Ion Center, Shanghai, People’s Republic of China; 9Department of Nuclear Medicine, Shanghai Proton and Heavy Ion Center, Fudan University Cancer Hospital, Shanghai, People’s Republic of China; 10Department of Radiology, Shanghai Proton and Heavy Ion Center, Fudan University Cancer Hospital, Shanghai, People’s Republic of China; 11Department of Radiation Oncology, Shanghai Concord Cancer Hospital, Shanghai, People’s Republic of China*These authors contributed equally to this workCorrespondence: Qing ZhangDepartment of Radiation Oncology, Shanghai Proton and Heavy Ion Center, Shanghai, People’s Republic of ChinaTel [phone]Fax [phone]Email [email protected] FuDepartment of Radiation Oncology, Shanghai Proton and Heavy Ion Center, Shanghai, People’s Republic of ChinaEmail [email protected]: The purpose of this study was to assess the potential of 99mTc-labeled PSMA-SPECT/CT and diffusion-weighted image (DWI) for predicting treatment response after carbon ion radiotherapy (CIRT) in prostate cancer.Patients and Methods: We prospectively registered 26 patients with localized prostate cancer treated with CIRT. All patients underwent 99mTc-labeled PSMA-SPECT/CT and multiparametric magnetic resonance imaging (MRI) before and after CIRT. The tumor/background ratio (TBR) and mean apparent diffusion coefficient (ADCmean) were measured on the tumor and the percentage changes before and after therapy (ΔTBR and ΔADCmean) were calculated. Patients were divided into two groups: good response and poor response according to clinical follow-up.Results: The median follow up time was 38.3months. The TBR was significantly decreased (p=0.001), while the ADCmean was significantly increased compared with the pretreatment value (p< 0.001). The ΔTBR and ΔADCmean were negatively correlated with each other (p = 0.002). On ROC curve analysis for predicting treatment response, the area under the ROC curve (AUC) of ΔTBR (0.867) for predicting good response was higher than that of ΔADCmean (0.819). The AUC of combined with ΔTBR and ΔADCmean (0.895) was higher than that of either ΔADCmean or ΔTBR alone. The combined use of ΔTBR and ΔADCmean showed 91.4% sensitivity and 95.2% specificity.Conclusion: Our preliminary data indicate that the changes of TBR and ADCmean maybe an early bio-marker for predicting prognosis after CIRT in localized prostate cancer patients. In addition, the ΔTBR seems to be a more powerful prognostic factor than ΔADCmean in prostate cancer treated with CIRT.Keywords: PSMA, DWI, prostate cancer, carbon ion radiotherapy

Keywords

• psma
• dwi
• prostate cancer
• carbon ion radiotherapy