Comparison of methods for determining absolute left ventricular volumes from radionuclide ventriculography

Several radionuclide techniques have been used in routine clinical nuclear medicine practice as a means of quantitating left ventricular chamber volumes in man. Despite wide use and availability of the different techniques, however, there has not been a thorough comparison of radionuclide and contrast angiographic measurements performed in the same patients in close temporal proximity. Accordingly, in order to validate traditional methods of ventricular volume measurement, we have performed contrast ventriculography followed immediately (upon return of baseline hemodynamics) by gated radionuclide ventriculography in 34 patients undergoing diagnostic cardiac catheterization. Absolute left ventricular end-diastolic volumes were determined from single-plane, right anterior oblique, end-diastolic contrast silhouettes using a standard area-length method. Radionuclide ventriculographic volumes were determined by three methods: planimetry (32 patients), counts-based (19 patients), and thermodilution stroke volume/radionuclide ejection fraction (32 patients). With planimetry, an area-length method was used in which the modified left anterior oblique left ventricular image was assumed to be a prolate ellipsoid whose volume can be determined by measuring surface area and the ventricular long axis. With the counts-based technique, a blood sample was drawn at the midpoint of the radionuclide ventriculogram acquisition and counted with a gamma camera with appropriate attenuation factor correction. With the thermodilution stroke volume/radionuclide ejection fraction technique, the left ventricular stroke volume was determined by dividing thermodilution cardiac output by the heart rate.(ABSTRACT TRUNCATED AT 250 WORDS)