Comparison of ejection fractions obtained from radionuclide first-pass and gated equilibrium bloodpool studies
It is possible to determine left ventricular ejection fractions (LVEFs) from data acquired during the first-pass (FPASS) of the myocardial perfusion agent technetium-99m sestamibi. This study was undertaken to determine which of three possible methods of analysis FPASS data gave results which agreed best with the LVEFs calculated from routine gated equilibrium bloodpool studies. In the first method a time-activity curve was used with subtraction of background from a region of interest (ROI) around the left ventricle. Different ROIs were examined. The second and third methods employed a representative cycle. In the second method an extracardiac ROI was used for background correction and in the third method a summed frame obtained from the lung phase. This study showed that the first method gave results which agreed best with values from gated equilibrium bloodpool studies (FPASS EF = 0,722b + 8,913, r = 0,84, where b = gated equilibrium bloodpool EF). Inter- and intra-observer analyses proved that this method was a reliable and reproducible technique to determine EF. It is important to note that a difference exists between absolute values of EF measured with FPASS or gated equilibrium bloodpool studies. This should be taken into consideration when criteria of 'normal' are chosen for different techniques.