Normal limits of left ventricular volumes and ejection fraction measured by gated myocardial perfusion SPECT: comparison of Tc-99m MIBI and Tl-201

We evaluated radioisotope and sex-specific differences of normal limits for left ventricle volumes (LWs) and ejection fraction (EF) using myocardial perfusion gated SPECT (g-SPECT). Rest Tl-201/post-stress Tc-99m MIBI g-SPECT measurements with acquisitions of 8-frame were evaluated for 70 patients (mean age 55 ± 14, 56% female) who either had <10% pretest likelihood of CAD (n=12) or had normal coronary angiography (EF > 50%) (n=58). LVEF, LWs were automatically determined by quantitative gated SPECT using QGS program. Similar results were obtained for mean LVEF between Tc-99m MIBI (62% ± 7%) and Tl-201 (63% ± 8%) g-SPECT measurements. In contrast, Tl-201 g-SPECT had significantly lower LWs values (EDV; 74 ± 23 mL, ESV; 28 ± 14 mL) than Tc-99m MIBI g-SPECT (EDV; 82 ± 25 mL, ESV; 32 ± 15 mL) (p<0.05). Women had significantly lower EDV (Tc-99m MIBI; 71 ± 18 mL, Tl-201; 65 ± 17 mL), and ESV values (Tc-99m MIBI; 27 ± 10 mL, Tl-201; 23 ± 8 mL) compared with EDV (Tc-99m MIBI; 96 ± 27 mL, Tl-201; 85 ± 24 mL), and ESV values (Tc-99m MIBI; 40 ± 17 mL, Tl-201; 36 ± 16 mL) of men (p<0.05). Women had significantly higher LV EF values (65% ± 7%) than men (60% ± 8%) by Tl-201 gated SPECT (p<0.05). These data suggest significant differeuces in normal limits for LWs and EF, according to genders and radiopharmaceutical. Therefore, the evaluation of cardiac function in patients should consider radioisotope and sex-matched normal values