TY - JOUR T1 - Detecting fibroblast activation proteins in lymphoma using <sup>68</sup>Ga-FAPI PET/CT JF - Journal of Nuclear Medicine JO - J Nucl Med DO - 10.2967/jnumed.121.262134 SP - jnumed.121.262134 AU - Xiao Jin AU - Maomao Wei AU - Shuailiang Wang AU - Guochang Wang AU - Yumei Lai AU - Yunfei Shi AU - Yan Zhang AU - Zhi Yang AU - Xuejuan Wang Y1 - 2021/05/01 UR - http://jnm.snmjournals.org/content/early/2021/05/27/jnumed.121.262134.abstract N2 - Purpose: Cancer-associated fibroblasts (CAFs) that overexpress fibroblast activation protein (FAP) are enriched in many epithelial carcinomas and in hematological neoplasms. Positron emission tomography/computed tomography (PET/CT) with radiolabeled FAP inhibitor (FAPI) is a new diagnostic tool for visualizing the tumor stroma. This prospective study aimed to profile FAPs in different subtypes of lymphomas and explore the potential utility of 68Ga-FAPI PET/CT in lymphomas. Methods: In this prospective study, we recruited 73 lymphoma patients who underwent 68Ga-FAPI PET/CT and recorded and measured semiquantitative parameters and ratios of their scan results. FAPI expression was assessed by immunochemistry in samples obtained from 22 of the lymphoma patients. Results: We evaluated 11 patients with Hodgkin lymphoma (HL) and 62 with non-Hodgkin lymphoma (NHL). Significantly elevated FAP uptake was observed in HL lesions, correlating with the intensity of FAP immunostaining (score, 3+). A positive association was found between the corresponding clinical classification of NHL and the 68Ga-FAPI uptake activity of the lesion. Aggressive NHL lesions, with moderate-to-strong FAP immunostaining (score, 2+ to 3+), exhibited intense to moderate 68Ga-FAPI uptake. Indolent NHL lesions showed weak FAP staining and mild to moderate 68Ga-FAPI uptake. No statistically significant correlation emerged between the sum of the product of the diameters and the corresponding maximum standardized uptake value (P = 0.424). The tumor-to-liver ratios were 6.26 ± 4.17 in indolent NHL and &gt; 9 in other subtypes. Conclusion: 68Ga-FAPI imaging can be used to detect FAP expression in lymphoma lesions and may be an alternate method for characterizing lymphoma profiles. ER -