Attenuated end-diastolic and end-systolic left ventricular counts which obtained from cardiac gated blood poo1 scan were corrected using experimentally calculated attenuation coefficient (μ=0.13/cm) and depth of center of left ventricle. This method was confirmed to be correct experimentally using phantom balloon. To compare the accuracy of attenuated and attenuation- corrected left ventricular volume measurement authors studied 10 patients with ischemic heart disease who underwent both gater blood pool sca and X-ray contrast ventriculography within a week. The attenuated and attenuation-corrected left ventricular volume measured by count method correlated with contrast ventriculographic volumes; however, attenuation corrected measurement was correlated more closely.