RT Journal Article SR Electronic T1 Detecting fibroblast activation proteins in lymphoma using 68Ga-FAPI PET/CT JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP jnumed.121.262134 DO 10.2967/jnumed.121.262134 A1 Xiao Jin A1 Maomao Wei A1 Shuailiang Wang A1 Guochang Wang A1 Yumei Lai A1 Yunfei Shi A1 Yan Zhang A1 Zhi Yang A1 Xuejuan Wang YR 2021 UL http://jnm.snmjournals.org/content/early/2021/05/27/jnumed.121.262134.abstract AB 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 > 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.