Removal of liver activity contamination in teboroxime dynamic cardiac SPECT imaging with the use of factor analysis

One of the major problems associated with technetium 99m teboroxime cardiac imaging is the high concentration of activity in the liver. In some cases it is impossible to diagnose defects on the inferior wall because of the finite resolution and scatter that cause images of the inferior wall and the liver to overlap.

The least-squares factor analysis of dynamic structures method, with correction for non-unique solutions, was used to remove the liver activity from the image. The method was applied to dynamically acquired Tc-99m teboroxime data. The liver activity removal method was tested through use of computer simulations and tomographically acquired canine and patient cardiac studies. In all studies the least-squares factor analysis of dynamic structures method was able to extract the liver activity from the series of dynamic images, thereby making it possible to remove it quantitatively from the entire series. The method was used successfully to remove the liver activity that partially overlapped the inferior wall in normal hearts. The method tends to increase the contrast between defects and normal myocardial tissue in abnormal hearts.

The method presented can be used to assist in diagnosis of cardiac disease when dynamically acquired teboroxime data are used. Because the contrast between the defect and normal myocardial tissue can be changed, the processed image cannot be used by itself to make an accurate diagnosis. However, with the liver activity removed, the image provides additional information that is very useful in the imaging of patients whose liver activity overlaps the inferior heart wall.