1Frank Laboratory, Radiology and Imaging Sciences, National Institutes of Health, Bethesda, MD, United States, 2Center for Infectious Disease Imaging (CIDI), Radiology and Imaging Sciences, National Institutes of Health, Bethesda, MD, United States, 3National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD, United States