Respiratory motion influence on ECG-gated SPET: a simulation study

Myocardial SPET has emerged as an important noninvasive diagnostic and prognostic method for assessment of patients with suspected CAD. Respiratory motion is a potential cause of motion artefact and reduced image quality in ECG-gated SPET (GSPET). In this investigation, we studied the effects of respiratory motion on GSPET concerning regional myocardial perfusion and function by simulation study. The NCAT phantom allowed simulation of respiratory motion with different amplitude for diaphragm (0 to 7 cm with increment of 1 cm) and anterior-posterior extension (from 0 to 1.7 cm). SimSET was used to generate simulated projection data. Emission data were generated over one respiratory cycle, divided into 80 phases. Data were reconstructed using the ordered subsets exceptional maximization (OSEM) method without attenuation and scatter correction. Quantitative analysis of regional myocardial perfusion and function were performed by Emory cardiac toolbox software. Our results demonstrated the effect of respiratory motion on LVEDV, LVESV, LVSV, LVEF, regional myocardial perfusion; mean segmental wall motion and wall thickening for different amplitudes of the respiratory motion. An increase in the distance of motion led to a significant decrease in LVEDV, LVESV, LVSV and LVEF (p < 0.01). Furthermore, our results showed that the mean segmental WM and WT were significantly increased with increase in respiratory motion from 2 to 7 cm compared to those with no motion (P < 0.01). In addition, the mean percentage of count density in the basal inferior, mid inferior, apical inferior, basal septal and mid septal segments were significantly lower in the presence of respiratory motion as compared to no motion (p < 0.01). Respiratory motion has significant effect on the LV functional analysis and regional myocardial perfusion in the GSPET. The amount of deterioration in cardiac functional and perfusion parameters as well as quality distortion of the images depends on the amplitude of the respiratory movement.