[Reproducibility of measurements of left ventricular function with gated myocardial perfusion SPECT and comparison with blood pool radionuclide ventriculography].

Introduction And Objective: This study was designed to evaluate the reproducibility of ejection fraction (EF) and ventricular volume measurements obtained with single photon emission computed tomography (gated-SPECT), and to assess the correlation between EF values obtained with this method and blood pool planar radionuclide ventriculography.

Patients And Method: A total of 55 patients were included (37 men, mean age 61.3 years) upon referral to two nuclear cardiology units for diagnosis (50%) or follow-up of known coronary artery disease. In a standard 2-day protocol, patients received a dose of [99mTc]tetrofosmin (800 MBq) at stress and at rest. Two resting gated-SPECT studies were performed. QGS software was used to obtain left ventricular EF, end-diastolic volume (EDV) and end-systolic volume (ESV). Forty-nine patients agreed to undergo blood pool ventriculography on the third day.

Results: Interobserver variability was 0.5 (2.6)% (r=0.99) for EF, 1.9 (10.7) mL for EDV (r=0.98) and 0.5 (5.4) mL for ESV (r=0.99). Interassay variability was 2 (5.1)% (r=0.94) for EF, 4.5 (8.6) mL for EDV (r=0.99) and 3.4 (6.6) mL for ESV (r=0.99). The correlation between gated-SPECT EF and blood pool EF was suboptimal (r=0.75, 95%CI, 0.59-0.85).

Conclusions: There was excellent interobserver and interassay reproducibility for left ventricular functional parameters measured with gated-SPECT and QGS software, and this method can be used for serial evaluations of ventricular function. Although the correlation between values obtained with gated-SPECT and blood pool ventriculography was acceptable, the differences show that the two techniques cannot be considered equivalent.