Pinhole radionuclide ventriculography in small infants.

Radionuclide equilibrium gated ventriculograms were performed in 23 infants before and after surgery for congenital heart disease using standard parallel hole general purpose collimation followed by a pinhole collimation technique to magnify images and improve spatial resolution. A second group of nine infants had pinhole collimated gated ventriculography during cardiac catheterization for comparison with cineangiographic ejection fraction. In group I, pinhole collimation gave improved ventricular and atrial separation over general purpose parallel collimation for determination of left ventricular ejection fraction (42 of 42 studies calculable vs 37 of 42) and for right ventricular ejection fraction (36 of 37 studies calculable vs 20 of 37). In patients with transposition, pinhole technique allowed right ventricular ejection determination in nine of nine studies but in only one of nine was right ventricular ejection fraction possible by standard parallel collimation. In group II, the correlation between left ventricular ejection fraction by cineangiography and pinhole radionuclide ventriculography was excellent (r = 0.95). The correlation for right ventricular ejection fraction between cineangiography and pinhole radionuclide ventriculography was 0.82. Pinhole radionuclide ventriculography is a useful, practical clinical tool that can be used to assess ventricular function in small infants in an intensive care or outpatient setting.