A simplified method for the calculation of left ventricular volume by equilibrium radionuclide angiography

Abstract

Abstract We have recently reported on the relationship between left ventricular (LV) volume (V) determined by contrast ventriculography (CV) and corresponding volume units calculated from LV region‐of‐interest counts obtained from ECG gated equilibrium radionuclide angiographic (EQ) time‐activity curves. We corrected the absolute number of counts at end‐diastole (ED) and end‐systole (ES) for the number of processed cardiac cycles, acquisition time, and counts in plasma at the time of the data acquisition. To evaluate a simpler method, which merely involves correcting for counts in whole blood rather than plasma, we studied 15 patients prospectively prior to CV. Each patient underwent EQ using 15–20 mCi of 99m Tc‐human serum albumin. Ten ml of blood were withdrawn at the midpoint of each study. Four ml were suspended above the scintillation camera detector to determine the “blood” radioactivity concentration. For comparison, the remaining 6 ml were centrifuged to yield 0.1 ml of plasma and counted separately in a well counter. ED and ES counts were obtained by using a standard commercial semi‐automatic computer program with a varying LV region‐of‐interest edge tracking algorithm. Radionuclide derived volume units by both methods were correlated with CV volume, yielding the following results: when counting plasma, for EDV, r = 0.94, and for ESV, r = 0.95; using the simpler blood counting method, for EDV, r = 0.93, and for ESV, r = 0.94. We conclude that LV volume can be calculated using count‐derived radionuclide volume units.