| Objective1. To investigate the myocardial perfusion in normal segments in diastolic phase using contrast-enhanced first-pass dual-energy CT imaging, which can be future basis for the evaluation of ischemic heart disease.2.To assess the accuracy of DECT for the early perfusion defect sign in comparison with adenosine stress single photon emission computed tomography (SPECT).3. To evaluate the relationship between the extent of coronary artery stenosis and the myocardial ischemia by DECT.Materials and methodsGroup A(control group) 20 volunteers (11 female,9 male, average age 53.10±9.73 years, average heart rate 66.5±7.93bpm) and group B (lesion group)39 patients with clinical suspected ischemic heart disease (9 female, 30 male, average age 66.67±12.64 years, average heart rate 63.59±7.26 bpm) who had a SPECT stress test and DECT perfusion were included. DECT myocardial perfusion was evaluated for the attenuation value (VNC and Overlay) using a 17-segment model. EPD was detected by DECT and was correlated with SPECT, the relationship between extent of coronary artery stenosis and the consistency of two methods were analyzed. DECT measurement of EPD, its peripheral and its opposite segment were made based on SPECT evaluation. SPSS 16.0 was used for the statistics.Results 1. In group A, there were no significant differences in VNC and Overlay between the apical, mid-ventricular and basal segments by DECT(P=0.24, P=0.318). In the same ventricular slice, there were no significant differences between anterior and septal segments in VNC, which can be grouped together (group A1), as well as inferior and lateral segments (group A2). There was no significant difference between anterior, septal, inferior and lateral segments in Overlay (P=0.866).2.92 segments showed early perfusion defects on DECT, and 53 segments were confirmed by SPECT in group B. Two exams diagnosed early perfusion defects without significant difference (X2=3.403, P=0.065). The number of EPD on DECT had a moderate correlation against SPECT (r= 0.533, P<0.01). Correlated with SPECT, DECT detected myocardial ischemia with sensitivity of 75.7%, specificity of 93.4%, accuracy of 91.6%, positive predictive value of 57.6% and negative predictive value of 97.0%. There were no significant differences in perfusion value between consistent group(group B1) and inconsistent group(group B2).3. Significant differences were found in the number of EDP in LAD, CX lesions group and mild stenosis group between two exams, P values were 0.022,0.034, and 0.001, respectively; In RCA lesions group, moderate stenosis and severe stenosis group, there were no significant differences between two exams, P values were 0.293,0.120, and 0.653, respectively.Conclusion1. Quantification of first-pass DECT myocardial perfusion allowed characterization of myocadial perfusion in healthy people and patients with myocardial ischemia. The comparison of DECT with SPECT showed that EDCT can identify myocardial perfusion defects with high diagnostic accuracy.2. The correlation between two exams was agree with the extent of conoray artery stenosis. DECT may be more sensitive in detecting early, mild defects than SPECT.PartⅡClinical Application and Significance of Left Ventricular Function by Dual-energy CTObjective 1. To evaluate the diagnostic value of DECT for the assessment of regional left ventricular function in normal segments during the cardiac cycle.2. To assess the accuracy of DECT in comparison with echocardiography for assessment of global left ventricular function.3. To investigate the relationship between the number and extent of coronary artery stenosis and the left ventricular function measurements.Materials and MethodsGroup A (control group) 25 healthy volunteers (15 female,10 male, average age 55.6±10.37 years, average heart rate 68.1±9.08 bpm) and group B (lesion group)65 patients with clinical suspected ischemic heart disease (11 female,54 male, average age 65.6±12.35 years, average heart rate 64.6±8.08 bpm) who underwent DECT and 2D-ECHO were included. The images of the heart were reconstructed at 5% of the R-R interval and were evaluated at end-diastole and end-systole. The regional left ventricular function was measured for the WTES, WTED, WT, WM using a 17-segment model in healthy volunteers. Compared left ventricular function measurements obtained by DECT and 2D-ECHO. DECT findings were evaluated between group A and group B, to investigate the association of coronary lesion with the left ventricular function measurements.Results1. In group A, WTES was significantly thicker than WTED for each segment (t=6.53, P<0.01). WTED, WM increased and WT decreased from apical, mid-ventricular to basal segments, statistically significant differences were noted in WTED and WT (P=0.01). The WTES of mid-ventricular segments were significantly higher than those of the basal segments (P<0.01). In the same ventricular slice, there were no significant differences in regional left ventricular function between anterior and septal segments which can be grouped together(group Al), as well as inferior and lateral segments(group A2). WTES, WT and WM of group A 1 were lower than those of group A2, WTED of group Al were greater than those of group A2 in the same ventricular slice (P<0.01). WTES, WT and WM of LAD territories were lower than those of RCA and CX(P<0.05),and WTED of LAD territories were greater than of RCA (P<0.01). 2. Both DECT and 2D-ECHO in assessment of IVSd, LVDd, LVPWd and EF had a good correlation for group A (r=0.866/0.946/0.851/0.822); IVSs,LVDs,LVPWs and FS had a middle-value-related(r=0.756/0.760/0.623/0.772). DECT slightly underestimating IVSd, LVDd, LVPWd, IVSs, LVDs and EF value compared with ECHO, and slightly overestimating LVPWs and FS. Statistically significant differences were noted in LVDd, LVPWd, LVDs and LVPWs between two exams(P<0.05).3. In group B, IVSd, LVDd, LVPWd, IVSs, LVDs, EF and FS yielded a good correlation (r=0.830/0.901/0.812/0.834/0.831/0.871/0.817);LVPWs relevance of the middle (r=0.701). The correlation of IVSs,LVDs,LVPWs,FS in group B was higher than in group A. IVSd, LVDd, LVPWd, LVDs and EF measurements obtained by DECT were less than ECHO; IVSs, LVPWs and FS were more than ECHO in group B. There were significant differences in LVDd, LVPWd, LVDs and LVPWs between two exams (P<0.05).4. Group A of LVPWd, FS and EF were more than group B; IVSd, IVSs, LVPWs, LVDd and LVDs were less than group B, there were significant differences in EF value, LVDd and LVDs between two group(P<0.05). EDV, ESV, MM, CO, CI and SV in group A were less than in group B;EF value was more than group B (P<0.05).5. In the severe stenosis group or the multiple lesions group, EF, FS, CO and SV were less than the other groups, and MM was more than the other groups, there were significant differences in EF value, MM and SV (P<0.05).Conclusion1. DECT was enable to evaluate the regional and global left ventricular function, and compared with the ECHO, a good correlation was observed between two exams.2. The number and extent of coronary artery stenosis was agree with the extent of left ventricular disfunction. DECT can be a potential method for the comprehensive evaluation for cardiac function and coronary artery stenosis.Part III Preliminary Study of Correlation Between Myocardial Bridge and Myocardial Ischemia by Dual-energy CTObjectiveTo evaluate the positive rate and morphological characteristics of myocardial bridge-mural coronary artery (MB-MCA) and the relationship between MB-MCA and myocardial ischemia by DECT.Material and method 252 patients suspected or confirmed ischemic heart disease who underwent DECT were retrospectively analyzed on CT imgings. The length of MCA and thickness of MB were measured; the situation of MB, type of MCA, and the distribution of atherosclerosis were observed; the relationship between the types of myocardial bridge and the myocardial ischemia was analyzed.ResultsAmong 252 patients,62 sites of MB-MCA were detected in 54 (21.4%) cases. The average length of MCA was (23.61±6.40)·mm. The average thickness of MB was (2.21±0.38) mm.40(40/62,64.5%) MB-MCA were located on the LAD, 9(9/62,14.5%) on the first diagonal branch and 13(13/62,21.0%) on the CX. 66.2%(41/62) MCA were superficial type and 33.8%(21/62) were depth type.32(32/41,78%) sites of myocardial perfusion defects were detected in superficial type and 18(18/21,85.75%)sites were in depth type. The overall prevalence of coronary atherosclerosis of the proximal segment of MB-MCA was 53.2%(33/62), whereas the coronary artery atherosclerosis of the distal segment was 11.2%(7/62), respectively.ConclusionThis study can demonstrated the anatomical characteristics of MB-MCA, positive rate, and correlate between the types and narrow grade of MCA and myocardial ischemia by DECT.
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