Measurement of absolute left ventricular volume from gated blood pool studies.

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Abstract
A new method for obtaining absolute left ventricular volume from gated blood pool studies was evaluated in a torso phantom and in 35 patients who also underwent single-plane contrast ventriculography. Gated 40.degree. left anterior oblique and static anterior views were acquired. Left ventricular volume at end-diastole was given by the ratio of the attenuation-corrected end-diastolic count rate from the gated study to the count rate per ml from a blood sample. Attenuation correction was made by dividing the end-diastolic count rate by e-ud, where u = the linear attenuation coefficient of water and d = the distance from the skin marker to the center of the left ventricle in the anterior view divided by sin 40.degree. to yield the depth of left ventricle in the left anterior oblique view. In the phantom studies, the correlation between radionuclide and true volume was 0.99 (radionuclide = 1.03 true - 3 ml); the SE of the estimate was 8 ml. In the patient studies, the radionuclide end-diastolic volume was used to calibrate the left ventricular time-activity curve, yielding left ventricular volume throughout the cardiac cycle. The correlation between radionuclide and angiographic end-diastolic volume was 0.95 (radionuclide = 0.97 angiographic + 3 ml); the SE of the estimate was 36 ml. The correlation between radionuclide and angiographic end-systolic volume was 0.95 (radionuclide = 1.01 angiographic + 1 ml); the SE of the estimate was 33 ml. This method permits direct determination of absolute left ventricular volume without assumptions about the shape of the ventricle or the necessity of using regression equations to convert volume units to true volume.