Effect of respiratory motion on plaque imaging in the mouse using Tc-99m labeled Annexin-V
W. Paul Segars, Y. Wang, and B.M.W. Tsui
Transgenic mouse models bred to develop atherosclerotic plaques in the aorta are currently being used to investigate microSPECT imaging techniques to differentiate stable and vulnerable plaques. Respiratory motion is a major factor that can cause blurring and artifacts in the resulting microSPECT images. We investigate the effects of respiratory motion on microSPECT imaging of atherosclerotic plaques in the mouse using a new, realistic 4D digital mouse phantom developed in our laboratory.
Fig. 1. (Left) Mouse heart phantom with a plaque modeled in the aortic arch. (Right) Volume renderings (fused transmission and emission images) showing reduced plaque contrast in the case with an average respiratory motion.
METHODS AND MATERIALS:
anatomy of the phantom was based on magnetic resonance imaging (MRI) data from
The measured uptake in the plaques was found to decrease significantly with increasing levels of respiratory motion, Fig. 1. The reduction in plaque contrast was as high as 60% in the reconstructed images with an average cardiac respiratory motion of 2mm.
We conclude that respiratory motion contributes significantly to blurring and artifacts in microSPECT plaque imaging in small animals. The 4D digital mouse phantom is a useful tool to assess the effects of respiratory motion, to investigate optimal imaging parameters, and to design respiratory gating schemes for improved microSPECT imaging of plaques.
NIH Research Grant R01EB00168