Left ventricular function in response to dipyridamole stress: head-to-head comparison between (82)Rubidium PET and (99m)Tc-sestamibi SPECT ECG-gated myocardial perfusion imaging.

PURPOSE: Myocardial perfusion imaging (MPI) with (99m)Tc-sestamibi (sestamibi) SPECT and rubidium-82 ((82)Rb) PET both allow for combined assessment of perfusion and left ventricular (LV) function. We sought to compare parameters of LV function obtained with both methods using a single dipyridamole stress dose.

MATERIALS AND METHODS: A group of 221 consecutive patients (65.2 ± 10.4 years, 52.9% male) underwent consecutive sestamibi and (82)Rb MPI after a single dipyridamole stress dose. Sestamibi and (82)Rb summed rest (SRS), stress (SSS) and difference (SDS) scores, and LV end-diastolic (EDV) and end-systolic (ESV) volumes and left ventricular ejection fraction (LVEF) were compared.

RESULTS: Bland-Altman analysis showed that with increasing ESV and EDV the difference between the two perfusion tracers increased both at rest and post-stress. The mean difference in EDV and ESV between the two perfusion tracers at rest could both be independently explained by the (82)Rb SDS and the sestamibi SRS. The combined models explained approximately 30% of the variation in these volumes between the two perfusion tracers (R(2) = 0.261, p = 0.005; R(2) = 0.296, p < 0.001, for EDV and ESV respectively). However, the mean difference in LVEF between sestamibi and (82)Rb showed no significant trend post-stress (R(2) = 0.001, p = 0.70) and only a modest linear increase with increasing LVEF values at rest (R(2) = 0.032, p = 0.009).

CONCLUSIONS: Differences in left ventricular volumes between sestamibi and (82)Rb MPI increase with increasing volumes. However, these differences did only marginally affect LVEF between sestamibi and (82)Rb. In clinical practice these results should be taken into account when comparing functional derived parameters between sestamibi and (82)Rb MPI.