The role of [99mTc]Tc-HFAPi SPECT/CT in patients with malignancies of digestive system: first clinical experience
Xi Jia, Xinru Li, Bing Jia, Ye Yang, Yuanbo Wang, Yan Liu, Ting Ji, Xin Xie, Yu Yao, Guanglin Qiu, Huixing Deng, Zhaohui Zhu, Si Chen, Aimin Yang, Rui Gao
Abstract
Abstract Background Recently, PET/CT imaging with radiolabelled FAP inhibitors (FAPIs) has been widely evaluated in diverse diseases. However, rare report has been published using SPECT/CT, a more available imaging method, with [ 99m Tc]Tc-labelled FAPI. In this study, we evaluated the potential effect of [ 99m Tc]Tc-HFAPi in clinical analysis for digestive system tumours. Methods This is a single-centre prospective diagnostic efficiency study (Ethic approved No.: XJTU1AF2021LSK-021 of the First Affiliated Hospital of Xi’an Jiaotong University and ChiCTR2100048093 of the Chinese Clinical Trial Register). Forty patients with suspected or confirmed digestive system tumours underwent [ 99m Tc]Tc-HFAPi SPECT/CT between January and June 2021. For dynamic biodistribution and dosimetry estimation, whole-body planar scintigraphy was performed at 10, 30, 90, 150, and 240 min post-injection in four representative patients. Optimal acquisition time was considered in all the patients at 60–90 min post-injection, then quantified or semi-quantified using SUV max and T/B ratio was done. The diagnostic performance of [ 99m Tc]Tc-HFAPi was calculated and compared with those of contrast-enhanced CT (ceCT) using McNemar test, and the changes of tumour stage and oncologic management were recorded. Results Physiological distribution of [ 99m Tc]Tc-HFAPi was observed in the liver, pancreas, gallbladder, and to a lesser extent in the kidneys, spleen and thyroid. Totally, 40 patients with 115 lesions were analysed. The diagnostic sensitivity of [ 99m Tc]Tc-HFAPi for non-operative primary lesions was similar to that of ceCT (94.29% [33/35] vs 100% [35/35], respectively; P = 0.5); in local relapse detection, [ 99m Tc]Tc-HFAPi was successfully detected in 100% ( n = 3) of patients. In the diagnosis of suspected metastatic lesions, [ 99m Tc]Tc-HFAPi exhibited higher sensitivity (89.66% [26/29] vs 68.97% [20/29], respectively, P = 0.03) and specificity (97.9% [47/48] vs 85.4% [41/48], respectively, P = 0.03) than ceCT, especially with 100% (24/24) specificity in the diagnosis of liver metastases, resulting in 20.0% (8/40) changes in TNM stage and 15.0% (6/40) changes in oncologic management. Conclusion [ 99m Tc]Tc-HFAPi demonstrates a greater diagnostic efficiency than ceCT in the detection of distant metastasis, especially in identifying liver metastases.