COMPARISON OF TC-99(M)-SESTAMIBI AND TL-201-CHLORIDE TO ESTIMATE RIGHT-VENTRICULAR OVERLOAD IN CHILDREN

To evaluate right ventricular overload in paediatric patients with congenital cardiac disease (n = 25), the uptakes of Tl-201 and Tc-99(m)-sestamibi (Tc-99(m)-MIBI) were compared. Tc-99(m)-MIBI showed a clearer myocardial border and better contrast between the myocardium and ventricular cavity. Although hepatic activity may influence right ventricular myocardial activity, it did not have a significant effect on the quantitative data of myocardial uptake. The right ventricle-to-background (RV/BG) ratio and left ventricle-to-background (LV/BG) ratio were lower with Tc-99(m)-MIBI than with Tl-201, and the RV/LV count ratio was also significantly lower in the Tc-99(m)-MIBI study. The parameters of the RV/LV count ratios showed good correlations between the Tl-201 and Tc-99(m)-MIBI studies. The RV/LV pressure ratio was estimated using the formula: RV/LV pressure ratio = 0.99 (RV/LV(av)) + 0.02 (R = 0.90, P < 0.0001). To estimate RV overload or the RV/LV pressure ratio scintigraphically, we conclude that Tc-99(m)-MIBI be used instead of Tl-201. Tc-99(m)-MIBI studies are a good adjunct to perfusion studies when estimating RV pressure.