1. From the Department of Radiology, Molecular Imaging Program at Stanford (A.J.T., F.S., K.Y., A.M.M., M.M., A.C., H.E.D.L.), Department of Pediatrics, Division of Hematology/Oncology, Lucile Packard Children’s Hospital (S.L.S., A.P., H.E.D.L.), and Department of Biomedical Data Science (Y.L., Q.Z.), Stanford University, 725 Welch Rd, Stanford, CA 94304; and Subtle Medical, Menlo Park, Calif (P.G.).