Effects of age on radionuclide angiographic detection and quantitation of left-to-right shunts.

The usefulness of quantitative radionuclide angiography (RNA) in detecting left-to-right shunts and estimating shunt size in young children was assessed. The total population of 88 patients was divided into 2 groups: 23 patients 2 years of age and younger (mean 0.8 +/- 0.6 [+/- standard deviation] ) and 65 patients older than 2 years (mean 15 +/- 15 years). The accuracy of 2 different RNA shunt estimation techniques, the gamma variate and the Stewart-Hamilton approach, were compared with the estimations obtained at cardiac catheterization using Fick (88 patients) and indocyanine green dye-dilution techniques (20 patients). Automated data processing algorithms were used to determine the RNA estimations, thereby avoiding the effects of operator judgment and subjectivity on shunt estimation. Of the 88 patients, 16 had no shunt by Fick data (that is, estimation less than 20%) but had a left-to-right shunt demonstrated by cardiac catheterization cineangiocardiography. Nine of these patients had no shunt by RNA (that is, estimation less than 20%). For patients 2 years of age and younger, linear regression analysis of the Fick and gamma variate data provided a slope of 0.63 and a correlation coefficient of 0.82; analysis of the Fick and Stewart-Hamilton data provided a slope of 0.59 and a correlation coefficient of 0.79. For patients older than 2 years, analysis of the Fick and gamma variate data provided a slope of 0.63 and a correlation coefficient of 0.79; analysis of the Fick and Stewart-Hamilton data provided a slope of 0.64 and a correlation coefficient of 0.76.(ABSTRACT TRUNCATED AT 250 WORDS)