Left Ventricular Functional Evaluation And Clinical Usage Using Gated SPECT Myocardial Perfusion Imaging

Gated single photon emission computed tomography (SPECT) myocardial perfusionimaging can provide the information of myocardial perfusion and left ventricular function in thesame examination. It afffords the opportunity to evaluate post-exercise myocardial stunning, andto provide incremental diagnostic and prognostic value over perfusion data alone. Our studyaimed to detect the the clinic value of gated SPECT by comparing the three gated SPECTsoftware programs and evaluating post-ischemia myocardial stunning using gated SPECT.PART ONEQuantification of Left Ventricular Volumes and Ejection Fraction from Gated⁹⁹Tc^m-MIBI SPECT: A comparison of QGS, ECToolbox and 4D-MSPECTObjective To compare the three commercially available gated SPECT software programs:quantitative gated SPECT(QGS), Emory Cardiac Toolbox(ECToolbox), and Four-Dimensionalmodel SPECT(4D-MSPECT) for the calculation of left ventricular ejection fraction(EF),end-diastolic volume(EDV) and end-systolic volume(ESV). And using left ventriculography as areference, compare gated SPECT with it.Methods Two hundred and twelve patients with suspected or known coronary artery diseasewere examined using gated ⁹⁹Tc^m-MIBI SPECT. The three methods QGS,ECToolbox,4D-MSPECT were used for the estimation of EF₁,EDV₁,ESV₁. And 106 of the 212 patientsunderwent left ventriculography within one month of SPECT, EF₂,EDV₂,ESV₂ werecalculated.Results Correlation between the methods were excellent for EF₁,EDV₁ and ESV₁, thecorrelation coefficients among the 3 kinds of software were 0.89～0.91 for EF₁(P＜0.001), and0.97～0.98 for EDV₁ and ESV₁(P＜0.001). And For EF₁ and EDV₁, they showed significantdifferences amang the 3 methods (P＜0.001). They were significantly lower when estimated by4D-MSPECT[EF₁: (64.2±12.6)ï¼…, EDV₁: (98.1±39.5)ml] than by ECToolbox[EF₁:(68.3± 12.8)%,EDV₁: (108.2±39.0)ml], and lower when estimated by QGS[EF₁: (59.2±11.4)%,EDV₁: (88.8±35.5)ml] than by 4D-MSPECT. For ESV₁, there were no significant differencesamong QGS[(39.0±27.0)ml],ECToolbox[(37.9±31.4)ml] and 4D-MSPECT[(38.7±31.3)ml](P=0.92). Correlation between results of gated SPECT and left ventriculography was good forEF₂,EDV₂ and ESV₂, the correlation coefficients were 0.70～0.80 for EF₂(P＜0.001), 0.57～0.61for EDV₂(P＜0.001), and 0.87～0.89 for ESV₂(P＜0.001).Conclusion All three software programs showed good correlation between each pair, and havegood correlation with left ventriculography.PART TWOEarly Post-exercise Gated ⁹⁹Tc^m-MIBI SPECT to Evaluate Post-ischemicMyocardial StunningObjective This study was designed to apply gated SPECT for the evaluation of myocardialstunning after exercise test, and to investigate the value of myocardial stunning in detectingcoronary artery disease.Methods One hundred and eight patients with suspected coronary artery disease and thirtypatients with low likelihood of coronary artery disease were examined using gated ⁹⁹Tc^m-MIBISPECT. We carried out three data acquisitions: an early data acquisition starting 5～15min afterexercise, a delayed acquisition starting about 1.5h after exercise, and a rest data acquisition inanother day. Left ventricular ejection fraction and volumes were calculated using QGS software,and segmental wall motion and perfusion were scored. According to myocardial perfusionimaging, the 108 patients were divided into two groups: myocardial ischemia group (n=70), andnormal perfusion group (n=38). Compare EF,EDV,ESV and wall motion among the three dataacquisitions in myocardial ischemia group, normal perfusion group and low likelihood CADgroup.Results In low likelihood CAD group, significant differences were showed in EF among thethree data [early (71.3±6.1)%,delayed (67.4±7.4)%,rest (66.9±7.0)%, F=3.623,P=0.031],the early post-exercise EF values were higher than rest EF for 4.4%, however, Scheffe testshowed that difference was not significant (P=0.053). There were no significant differences in EDV and ESV values among the three data in low likelihood CAD group[EDV: early(66.1±14.5)ml,delayed(69.9±15.9)ml,rest(73.3±17.4)ml, F=1.527, P=0.223; ESV: early(19.5±7.5)ml,delayed(23.5±9.3)ml,rest(24.9±10.3)ml, F=2.847, P=0.063]. In normal perfusiongroup, no significant differences were showed in EF,EDV and ESV among the three data[EF:early(70.3±6.0)%,delayed(67.2±6.9)%,rest(67.4±6.1)%, F=2.921, P=0.058; EDV:early(67.0±19.0)ml,delayed(67.6±20.0)ml,rest(68.3±19.6)ml, F=0.043, P=0.958; ESV:early(20.6±8.9)ml,delayed(23.1±10.1)ml,rest(22.9±8.9)ml, F=0.833, P=0.4381. Inmyocardial ischemia group, the early post-exercise EF[(58.4±7.5)%] and delayed post-exerciseEF[(58.9±7.0)%] were significantly lower than rest EF[(62.5±6.7)%]. In 39% (27/70) ofpatients, early post-exercise EF was＞5% lower than that at rest, and in 37% (26/70) of patients,delayed post-exercise EF was＞5% lower than that at rest. While comparing the ESV values,there were significant differences among the three data[early(37.2±17.5)ml,delayed(36.6±16.3)ml,rest(30.2±13.3)ml, F=4.244, P=0.016]. Scheffe test showed that early postexerciseESV values were significantly increased than that at rest (P=0.033), however, delayed ESVvalues were no significantly increased than that at rest (P=0.059). The stress/rest ratioes were1.28 and 1.25, respectively. Using 1.22 as the transient ischemia dilation ratio threshold, dilationwas observed in 47% (33/70) of patients with early post-exercise imaging, and in 50% (35/70) ofpatients with delayed post-exercise imaging. However, no significant differences were observedin EDV values among the three data[eary(87.1±28.0)ml,delayed(86.6±27.8)ml,rest[(78.6±23.4)ml, F=2.279, P=0.105]. Among 70 patients, 77% had regional wall motion abnormality,61%(43/70) showed reversible wall motion abnormality during the early post-exercise periodcompared with rest, and 60%(42/70) showed reversible wall motion abnormality during thedelayed post-exercise period compared with rest. Good correlations were demonstrated amongthe decrease of EF, dilation of left ventricular end-systolic volumes and reversible regional wallmotion abnormality, and multivariate analysis showed that the summed difference score was theonly factor that correlated significantly with left ventricular dysfunction. However, we found nosignificant differences in EF,EDV,ESV and regional wall motion score between earlypost-exercise imaging and delayed post-exercise imaging. By analyzing the 44 patients whounderwent coronary angiography, we found that sensitivity of the combination of perfusion andreversible wall motion abnormality was increased from 92.7% to 95.1%, accuracy was increased from 93.2% to 95.5%, and specificity was the same.Conclusions In post-exercise gated single photon emission computed tomography myocardialperfusion imaging, myocardial stunning is frequently seen in patients with ischemia, and isequivalently detected by the decrease of post-exercise EF,dilation of left ventricular end-systolicvolume and reversible regional wall motion abnormality. And myocardial stunning is correlatedwith severity of exercise-induced perfusion defects, and can be predicted by the measurement ofthe extent and severity of ischemia. Detecting the exercise-induced myocardial stunning by gatedSPECT is important in clinic, combined post-exercise left ventricular dysfunction withmyocardial perfusion has incremental diagnostic value for detection of CAD.