In vivo Characterization of Four 18F-Labeled S1PR1 Tracers for Neuroinflammation. - Liu, Hui; Luo, Zonghua; Gu, Jiwei; Jiang, Hao; Joshi, Sumit; Shoghi, Kooresh I.; Zhou, Yun; Gropler, Robert J.; Benzinger, Tammie L. S.; Tu, Zhude (Molecular Imaging & Biology, 2020)