The effect of patient, acquisition and reconstruction variables on myocardial wall thickness as measured from myocardial perfusion SPECT studies

In assessing the size and severity of myocardial perfusion defects, either a count threshold is applied to the images, or they are compared to a database of healthy hearts. This study aims to determine the dependence of these databases and thresholds on patient, acquisition and reconstruction variables, by measuring myocardial wall thickness. Analysis was performed on myocardial perfusion studies from 38 normal patients and a series of phantom experiments. The variables investigated included patient gender, test type, liver interference, myocardium to background activity ratio, acquisition zoom factor, matrix size and reconstruction type. When attenuation correction (AC) and detector resolution compensation (DRC) was applied during reconstruction, no significant difference was found in myocardial wall thickness between males and females, rest and stress studies, the presence and absence of liver interference, or clinically relevant myocardium to background activity ratios. A significant difference was found between standard and zoomed acquisitions, and between simple reconstruction techniques and those containing SPECT corrections. Results suggest that when AC and DRC are applied during reconstruction, patient variables do not influence quantitative accuracy and therefore analysis does not require individual databases or thresholds. As reconstruction methods improve in accuracy and in their ability to reconstruct large matrices, new databases and thresholds will be needed, bringing us closer to perfect absolute quantitative accuracy