AUTHOR=Massey James C. , Seshadri Vikram , Paul Soumen , Mińczuk Krzysztof , Molinos Cesar , Li Jie , Kundu Bijoy K. 

TITLE=Model Corrected Blood Input Function to Compute Cerebral FDG Uptake Rates From Dynamic Total-Body PET Images of Rats in vivo

JOURNAL=Frontiers in Medicine

VOLUME=Volume 8 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/medicine/articles/10.3389/fmed.2021.618645

DOI=10.3389/fmed.2021.618645

ISSN=2296-858X

ABSTRACT=Recently, we developed a 3-compartment dual output model that incorporates spill over (SP) and partial volume (PV) corrections to simultaneously estimate the kinetic parameters and model corrected blood input function (MCIF) from dynamic FDG PET images of mouse heart in vivo. In this study, we further optimized this model and utilized the estimated MCIF to compute cerebral FDG uptake rates, Ki, from dynamic total-body FDG PET images of control Wistar-Kyoto (WKY) rats and compared to those derived from arterial blood sampling in vivo.

Dynamic FDG PET scans of WKY rats (n=5), fasted for 6 hours, were performed using the Albira Si Trimodal PET/SPECT/CT imager for 60 minutes. Arterial blood samples were collected for the entire imaging duration and then fitted to a 7-parameter function. The 60-minute list mode PET data, corrected for attenuation, scatter, randoms and decay, was reconstructed into 23 time bins. A 15-parameter dual output model with SP and PV corrections was optimized with two cost functions for the first time to compute MCIF. A 4-parameter compartment model was then used to compute cerebral Ki. The computed area under the curve (AUC) and Ki were compared to that derived from arterial blood samples for the first time.  

Experimental and computed AUC were 1893.53±195.39 kBq min/cc and 1792.65±155.84 kBq min/cc, respectively (p=0.76). Bland Altman analysis of experimental vs computed Ki for 35 cerebral regions in WKY rats revealed a mean difference of 0.0029 min-1(~13.5%). 

Direct (AUC) and indirect (Ki) comparisons of model computations with arterial blood sampling were performed for the first time in WKY rats. AUC and the downstream cerebral FDG uptake rates compared well with that obtained using arterial blood samples. Experimental vs computed cerebral Ki for the 4 super regions including cerebellum, frontal cortex, hippocampus, and striatum indicated no significant differences.