Assessment of congenital heart disease by a thallium-201 SPECT study in children

The characteristics of correlation between the right-to-left ventricular systolic pressure ratios (RVp/LVp) and the thallium-201 right-to-left ventricular (201Tl R/L) count ratios was investigated in children with various congenital heart diseases. High-resolution three-headed SPECT system equipped with either parallel-hole or fan-beam collimators was used. In a total of 102 patients, the correlation between RVp/LVp and 201Tl R/L average count ratios was good in both planar (r=0.89, p=0.0001) and SPECT studies (r=0.80, p=0.0001). Quantitative analysis of myocardial uptake by SPECT demonstrated the characteristic pattern of each disease as well as the differences in the right ventricular overload types. When the linear regression analysis was performed in each heart disease, ventricular septal defect showed most excellent correlation. Complex heart anomalies also showed positive correlation (r=0.51, p=0.05) with RVp/LVp, and it can be used to estimate right ventricular pressure. After surgical treatment of tetralogy of Fallot and pulmonary stenosis, the decrease of 201Tl R/L count ratio was in accordance with improvement of right ventricular overload. We conclude that 201Tl SPECT study can be a good indicator for estimation of right ventricular pressure. (author)