@article {Herrero477, author = {Pilar Herrero and Joonyoung Kim and Terry L. Sharp and John A. Engelbach and Jason S. Lewis and Robert J. Gropler and Michael J. Welch}, title = {Assessment of Myocardial Blood Flow Using 15O-Water and 1-11C-Acetate in Rats with Small-Animal PET}, volume = {47}, number = {3}, pages = {477--485}, year = {2006}, publisher = {Society of Nuclear Medicine}, abstract = {This feasibility study was undertaken to determine whether myocardial blood flow (MBF, mL/g/min) could be quantified noninvasively in small rodents using microPET and 15O-water or 1-11C-acetate. Methods: MBF was measured in 18 healthy rats using PET and 15O-water (MBF-W) under different interventions and compared with direct measurements obtained with microspheres (MBF-M). Subsequently, MBF was estimated in 24 rats at rest using 1-11C-acetate (MBF-Ace) and compared with measurements obtained with 15O-water. Using factor analysis, images were processed to obtain 1 blood and 1 myocardial time{\textendash}activity curve per tracer per study. MBF-W was calculated using a well-validated 1-compartment kinetic model. MBF-Ace was estimated using a simple 1-compartment model to estimate net tracer uptake, K1 (K1 (mL/g/min) = MBF{\textperiodcentered}E; E = first-pass myocardial extraction of 1-11C-acetate) and washout (k2 (min-1)) along with FBM (spillover correction) after fixing FMM (partial-volume correction) to values obtained from 15O-water modeling. K1 values were converted to MBF values using a first-pass myocardial extraction/flow relationship measured in rats (E = 1.0-0.74{\textperiodcentered}exp(-1.13/MBF)). Results: In the first study, MBF-W correlated well with MBF-M (y = 0.74x + 0.96; n = 18, r = 0.91, P \< 0.0001). However, the slope was different than unity, P \< 0.05). Refitting of the data after forcing the intercept to be zero resulted in a nonbias correlation between MBF-W and MBF-M (y = 0.95x + 0.0; n = 18, r = 0.86, P \< 0.0001) demonstrating that the underestimation of the slope could be attributed to the overestimation of MBF-W for 2 MBF-M values lower than 1.50 mL/g/min. In the second study, MBF-Ace values correlated well with MBF-W with no underestimation of MBF (y = 0.91x + 0.35; n = 24, r = 0.87, P \< 0.0001). Conclusion: MBF can be quantified by PET using 15O-water or 1-11C-acetate in healthy rats. Future studies are needed to determine the accuracy of the methods in low-flow states and to develop an approach for a partial-volume correction when 1-11C-acetate is used.}, issn = {0161-5505}, URL = {https://jnm.snmjournals.org/content/47/3/477}, eprint = {https://jnm.snmjournals.org/content/47/3/477.full.pdf}, journal = {Journal of Nuclear Medicine} }