Assessment of left ventricular function by Tl-201 SPECT using left ventricular cavity-to-myocardium count ratio

Equilibrium radionuclide angiography (ERNA) is the 'gold standard' for asse ssing left ventricular ejection fraction (LVEF). The aim of the study was t o determine whether the left ventricular cavity-to-myocardium count ratio ( LVCMR) from Tl-201 myocardial single photon emission computed tomography (S PECT) correlated with LVEF assessed hy ERNA. The study group included 159 c onsecutive patients (117 male, 12 female), aged 59 +/- 12 years, who underw ent both Tl-201 SPECT and ERNA at rest on the same day. The LVCMR was calcu lated from a mid-ventricular short axis slice on redistribution studies, us ing two regions of interest (ROIs). One ROI was placed in the centre of the left ventricular cavity (C) and the other was placed in the myocardium wit h maximum uptake (M-max): LVCMR =(C/M-max) x 100. The correlation between L VCMR and LVEF was r = 0.85 (y = 0.943x+5.002; P <0.0001). The mean calculat ed values +/-1 SD were LVCMR=54+/-16% and LVEF=52+/-15%. In conclusion, LVC MR from Tl-201 SPECT studies was closely correlated with LVEF from ERNA stu dies and can be used to easily and rapidly estimate left ventricular functi on. ((C) 2001 Lippincott Williams & Wilkins).