Global and regional functional measurements with gated FDG PET in comparison with left ventriculography

Abstract

The purpose of this study was to validate the measurement of global and regional left ventricular cardiac function with ECG-gated fluorine-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) by comparison with the corresponding indices from X-ray left ventriculography (LVG). Twenty-six patients (23 men, 3 women, mean age 60.4 years) underwent LVG and ECG-gated (eight frames/cycle) FDG-PET within an interval of 10.2±6.8 days. A volumetric sampling approach was used to obtain both global (EF: ejection fraction) and regional [%WT: relative regional count increase from end-diastolic (ED) to end-systolic (ES) phase] functional parameters. The gated PET parameters were compared with the corresponding findings of LVG in seven myocardial segments. EF(gated PET) and EF(LVG) did not differ significantly (30%±10% vs 32%±10%, P=NS). The two EF values correlated significantly, showing no significant systematic measurement bias [EF(gated PET) = 2.61+0.86 × EF(LVG), R=0.84, P<0.0001]. Inter- and intra-observer reproducibility for EF were R=0.95, P<0.0001 and R=0.92, P<0.0001, respectively. Regional function was evaluated with LVG in 144 myocardial segments comprising 35 normokinetic, 70 hypokinetic and 39 a/dyskinetic segments. Visual analysis of LVG and gated PET correlated significantly (P<0.001), with an overall concordance ratio of 58% (83/144, kappa=0.35). Gated PET overestimated the regional function in 27% (39/144) and underestimated it in 15% (22/144). %WT showed significant differences between each pair of groups (a/dyskinesis, 13.2%±9.3%; hypokinesis, 17.1%±8.8%; normokinesis, 21.8%±10.9%). Inter- and intra-observer reproducibility was significant for %WT (R=0.77, P<0.0001 and R=0.79, P<0.0001, respectively). In conclusion, gated FDG PET permits assessment of global left ventricular cardiac function. In addition, assessment of regional function is feasible using the visual or the quantitative parameters.