Positron emission tomography in the assessment of left ventricular function in healthy rats: A comparison of four imaging methods

Objective To measure left ventricular (LV) function parameters in heart of healthy rats by three different positron emission tomography (PET) imaging techniques and by magnetic resonance imaging (MRI). Methods ECG-gated microPET examinations were obtained in seven healthy rats with 2-deoxy-2-[18F]fluoro-d-glucose (FDG) for calculation of LV-function from the blood-pool phase of the dynamic recording (FDGBP), and also from the later myocardial uptake (FDGMyo). On subsequent days, we re-measured LV-function using the novel blood-pool tracer 68Ga-albumin (AlbBP) and again by FDG (FDGMyo2) in one setting. Cine-MRI examination provided the reference standard measurement. Results The mean LV ejection fractions (LVEF) were 56 ± 3 (FDGBP), 55 ± 3 (FDGMyo), 56 ± 3 (FDGMyo2), 57 ± 3 (AlbBP), and 57 ± 2 (MRI). There were good to excellent correlations found between the LVEF-values as compared to MRI reference standard for FDGBP (r = 0.71), FDGMyo (r = 0.86) and AlbBP (r = 0.88). Both of the blood-pool methods significantly overestimated the magnitudes of end-diastolic-volume and end-systolic-volume, whereas FDGMyo matched closely to the MRI reference standard. There was no significant bias for both blood-pool methods and a minor negative bias for FDGMyo regarding the LV ejection fraction (LVEF) when compared to cine-MRI results. There was no significant difference between the means of FDGMyo and FDGMyo2 (P = .50). Conclusions Relative to reference standard MRI measurements of LVEF, there was excellent agreement between PET-based measurements, notably for the novel blood-pool tracer 68Ga-albumin