Background: Recent advances in the treatment of primary pulmonary hypertension (PPH), and in surgery to correct tetralogy of Fallot (TOF), have rekindled interest in evaluating right ventricular (RV) volume and ejection fraction (EF). The purpose of this investigation was to determine the accuracy of RV functional parameters assessed by single photon emission computed tomography (SPECT) equilibrium radionuclide angiography (ERNA).
Methods and results: Twenty-eight patients with PPH (n = 15) or TOF (n = 13) (aged 28 +/- 14 years; 57% male) were analyzed by means of SPECT ERNA algorithms that automatically identified mid-RV tomographic planes, generated regions isolating the right ventricle from other structures, and presented RV-segmented regions as a cinematic display. RV EF and volumes were computed and compared with values obtained by magnetic resonance imaging (MRI). Mean values were not different between SPECT ERNA and MRI for RV EF, end-diastolic volume, and end-systolic volume (42% +/- 11% vs 41% +/- 10%, 135 +/- 67 mL vs 139 +/- 91 mL, and 87 +/- 54 mL vs 85 +/- 61 mL, respectively; P = not significant for all comparisons). Significant linear correlation (P <.0001) was found between SPECT ERNA and MRI for RV EF, end-diastolic volume, and end-systolic volume (r = 0.85, r = 0.94, and r = 0.93, respectively). No statistically significant trends or biases for RV EF were found. Intraobserver and interobserver comparisons demonstrated good reproducibility. As expected, RV volume was significantly higher and RV EF was significantly lower for patients with PPH and TOF than were values for individuals at low likelihood for coronary artery disease or other cardiac disease.
Conclusions: SPECT ERNA provides accurate, reproducible assessment of RV volumes and EF and should prove useful in evaluating the magnitude of RV dysfunction in patients and in providing an objective means with which to assess the results of therapeutic interventions.