Normal variability and test-retest reproducibility of myocardial blood flow measurements in mice using C-11 acetate and small animal PET imaging

Objectives This study aimed to quantitatively assess the reproducibility of measuring myocardial blood flow (MBF) in mice using C-11 acetate and tracer kinetic modeling.

Methods Three FVB mice were iv-injected with 30-60 MBq of C-11 acetate and PET data was acquired for 30 min and repeated 1 week later. Dynamic images were reconstructed using OSEM3D/MAP (β=0). FlowQuant^© automated analysis software produced polar maps of relative uptake at t=1.5-3 min and absolute MBF(mL/min/g) using a one-compartment model and the first 4 min of data.

Results The LV global mean ± SD uptake and MBF were found to be 76 ± 4% and 16.0 ± 3.0 mL/min/g corresponding to a population variability of 5% and 19% respectively. Regional coefficients of non-uniformity (SD/mean) were 0.11 ± 0.02 and 0.22 ± 0.04 (p<0.001) for uptake and MBF polar maps respectively indicating superior uniformity in the uptake maps. The global difference between repeat MBF scans was 2.0 ± 2.0 mL/min/g (p=NS). Segmental analysis of the test-retest uptake data showed no difference between segments (p=NS) with a mean difference of -0.9 ± 5.2%. The repeat MBF data showed a small segmental difference of 2.1 ± 2.8 mL/min/g (p<0.05). The coefficient of repeatability for C-11 acetate segmental uptake, global MBF and segmental MBF was 10.2%, 24.5% and 25.9% consistent with PET reproducibility studies in humans, pigs and rats.

Conclusions Uniform uptake and MBF values in the expected range were demonstrated. These results suggest this system and these analysis methods are reproducible for quantitative MBF imaging studies in mice using C-11 acetate PET.