Quantitative Total-Body Imaging of Blood Flow with High Temporal Resolution Early Dynamic 18 F-Fluorodeoxyglucose PET Kinetic Modeling.

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 ( K 1 ) 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.
Competing Interests: Disclosure The University of California, Davis has a research agreement and a revenue sharing agreement with United Imaging Healthcare. This work was supported in part by National Institutes of Health (NIH) grants R01 EB033435 and R61 AT012187. The image data of healthy participants were acquired under the support of NIH R01 CA206187 and P30 CA093373. The other authors declare no competing interests.