Abstract
Quantitative total-body PET imaging of blood flow can be performed with freely diffusible flow radiotracers such as (15)O-water and (11)C-butanol, but their short half-lives necessitate close access to a cyclotron. Past efforts to measure blood flow with the widely available radiotracer (18)F-fluorodeoxyglucose (FDG) were limited to tissues with high (18)F-FDG extraction fraction. In this study, we developed an early-dynamic (18)F-FDG PET method with high temporal resolution kinetic modeling to assess total-body blood flow based on deriving the vascular transit time of (18)F-FDG and conducted a pilot comparison study against a (11)C-butanol reference. METHODS: The first two minutes of dynamic PET scans were reconstructed at high temporal resolution (60×1 s, 30×2 s) to resolve the rapid passage of the radiotracer through blood vessels. In contrast to existing methods that use blood-to-tissue transport rate ( K1 ) as a surrogate of blood flow, our method directly estimates blood flow using a distributed kinetic model (adiabatic approximation to the tissue homogeneity model; AATH). To validate our (18)F-FDG measurements of blood flow against a flow radiotracer, we analyzed total-body dynamic PET images of six human participants scanned with both (18)F-FDG and (11)C-butanol. An additional thirty-four total-body dynamic (18)F-FDG PET scans of healthy participants were analyzed for comparison against literature blood flow ranges. Regional blood flow was estimated across the body and total-body parametric imaging of blood flow was conducted for visual assessment. AATH and standard compartment model fitting was compared by the Akaike Information Criterion at different temporal resolutions. RESULTS: (18)F-FDG blood flow was in quantitative agreement with flow measured from (11)C-butanol across same-subject regional measurements (Pearson R=0.955, p<0.001; linear regression y=0.973x-0.012), which was visually corroborated by total-body blood flow parametric imaging. Our method resolved a wide range of blood flow values across the body in broad agreement with literature ranges (e.g., healthy cohort average: 0.51±0.12 ml/min/cm(3) in the cerebral cortex and 2.03±0.64 ml/min/cm(3) in the lungs, respectively). High temporal resolution (1 to 2 s) was critical to enabling AATH modeling over standard compartment modeling. CONCLUSIONS: Total-body blood flow imaging was feasible using early-dynamic (18)F-FDG PET with high-temporal resolution kinetic modeling. Combined with standard (18)F-FDG PET methods, this method may enable efficient single-tracer flow-metabolism imaging, with numerous research and clinical applications in oncology, cardiovascular disease, pain medicine, and neuroscience.