Study of myocardial regional wall motion parameter's accuracy by software perfusion phantom.

Gated perfusion myocardial scintigraphy permits simultaneous evaluation of perfusion as well as regional contractile function of the left ventricle. Fourier analysis of regional myocardial spatial movement with respect to the myocardial geometric centre gives circular amplitude and phase profiles of ventricular contraction, in addition to regional maximum activity that represents an index of perfusion. To introduce such combined perfusion-contraction analysis the accuracy of the indices mentioned above should be evaluated for different doses of radioactivity typically administered to a patient. A mathematical software phantom, consisting of a half circularly profiled ring activity embedded in uniform background activity and noise generated by a Poisson-shaped random number generator, was constructed and used for this purpose. A 64 x 64 matrix and sequence of 16 frames per study was used. The maximum number of counts per pixel ranged from 10 to 100, simulating low count thallium and high count rate Tc-MIBI-gated studies. The relative standard error analysis (R.S.E.) with a 95.5% confidence level for a thallium type of 10 counts per pixel study exceeded 11%, while it reached acceptable values below 3% for studies with 60 and more counts per pixel. These results indicate that high count rate gated technetium-MIBI myocardial perfusion studies could also be used for reliable left ventricular regional wall motion evaluation.