Left ventricular synchrony assessed by phase analysis of gated myocardial perfusion SPECT imaging in healthy subjects

Abstract

Objective To investigate the value of Cedars-Sinai quantitative gated SPECT (QGS) phase analysis for left ventricular synchrony assessment in healthy subjects.Methods Seventy-four healthy subjects (41 males,33 females,average age:(60±13) years) underwent both rest and exercise 99Tcm-MIBI G-MPI.QGS software was used to analyze the reconstructed rest gated SPECT images automatically,and then the parameters of left ventricular synchrony including phase bandwidth (BW) and phase standard deviation (SD) were obtained.The influences of gender and age (age＜60 years,n =36; age ≥ 60 years,n =38) on left ventricular systolic synchronicity were analyzed.The phase angle for original segmental contraction was measured to determine the onset of the ventricular contraction using 17-segment model.Forty healthy subjects were selected by simple random sampling method to evaluate the intra-observer and interobserver repeatability of QGS phase analysis software.Two-sample t test and linear correlation analysis were used to analyze the data.Results The BW and SD of left ventricular in healthy subjects were (37.22 ±11.71)°,(11.84±5.39)° respectively.Comparisons between male and female for BW and SD yielded no statistical significance (BW:(36.00±9.70)°,(38.73±13.84)°; SD:(11.88±5.56)°,(11.79±5.26)°; t=0.96 and-0.07,both P＞0.05) ; whereas the older subjects (age≥60 years) had larger BW than the others (age＜60 years ; (39.95± 12.65) °,(34.33± 10.00) ° ; t =-2.11,P＜0.05) and no statistical significance was shown for SD between the two age groups ((11.18±4.31) °,(12.54±6.33) ° ; t =1.08,P＞0.05).Of the 74 subjects,the mechanical activation started from the ventricular base to apex in 54 subjects (73％),and from apex to base in only 20 subjects (27％).High repeatability of phase analysis was observed for both intra-observer and inter-observer (r=0.867-0.906,all P＜0.001).Conclusions Good left ventricular segmental synchrony is shown in healthy subjects.No gender difference exists for ventricular synchrony assessment.Age (＜60 years) is important for better synchrony.Cedars-Sinai QGS cardiac phase analysis software is valuable in quantitative assessment of left ventricular synchrony with high repeatability. Key words: Myocardial contraction synchrony; Ventricular function, left; Tomography,emission-computed, single-photon; Reference values; MIBI