Comparison of 99Tcm-sestamibi and 201Tl-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 201Tl and 99Tcm-sestamibi (99Tcm-MIBI) were compared. 99Tcm-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 99Tcm-MIBI than with 201Tl, and the RV/LV count ratio was also significantly lower in the 99Tcm-MIBI study. The parameters of the RV/LV count ratios showed good correlations between the 201Tl and 99Tcm-MIBI studies. The RV/LV pressure ratio was estimated using the formula: RV/LV pressure ratio = 0.99 (RV/LVav) + 0.02 (R = 0.90, P < 0.0001). To estimate RV overload or the RV/LV pressure ratio scintigraphically, we conclude that 99Tcm-MIBI be used instead of 201Tl. 99Tcm-MIBI studies are a good adjunct to perfusion studies when estimating RV pressure.