Abstract
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Objectives: Phase analysis technique from gated myocardial perfusion SPECT(GSPECT) with Tc-99m sestamibi has been widely used to measure left ventricular (LV) mechanical dyssynchrony (LVMD). Previous studies demonstrated that gated myocardial PET(GPET) with F-18 fluorodeoxyglucose (FDG) may provide more accurate LV functional parameters. However, whether GSPECT and GPET-derived phase parameters are interchangeable in patients with ischemic cardiomyopathy(ICM) remains to be defined. Therefore, we sought to compare the difference of parameters by phase analysis obtained from GSPECT and GPET in ICM patients and find which factor may affect the difference.
Methods: Eight-three consecutive patients with ICM [age 57±9 years, male 78, mean LV ejection fraction (EF) 23 ± 10 % by GSPECT; mean LVEF 29 ± 10% by GPET] who underwent myocardial viability assessment by GSPECT and GPET were retrospectively evaluated. LVMD by GSPECT and GPET were analyzed by QGS software, and histogram bandwidth (BW, .), standard deviation of (SD,.) and entropy(% ) were obtained. Relative percentage of difference (% difference) of BW, SD and entropy between GSPECT and GPET were calculated by the absolute difference between GSPECT and GPET divided by values of GSPECT.
Results: GPET yielded significantly higher SD (P<0.001) and lower entropy (P<0.05) in comparison with GSPECT. Moderate correlations were observed for BW(r =0.62, P<0.001); SD (r=0.62, P<0.001) and entropy (r=0.69, P<0.001 ) between GSPECT and GPET. Both BW and SD were significantly increased in patients with larger ESV, reduced LVEF and small extent of viable myocardium (P<0.01). Entropy was significantly increased in patients with larger ESV and reduced LVEF (P<0.01). Multivariate regression analysis revealed that ESV measured by SPECT was independently associated with % difference of BW (r =-0.25, P <0.05) and SD (r = -0.23, P<0.05). In addition, LVEF measured by SPECT was independently associated with % difference of entropy (r = 0.44, P <0.001), whereas myocardial viability had no correlation with difference of phase parameters (BW, SD and entropy) between GSPECT and GPET.
Conclusions: LVMD parameters (ESV, SD, and entropy) between GSPECT and GPET had moderate correlation in ICM patients. The clinical value needs further investigation.