Evaluation Of Viable Myocardium In Patients With Ischemic Cardiomyopathy By SPECT/CT Imaging

Objective:To investigate the value of Technetium-99m Labeled4,9-diaza-3,3,10,10-tetramethyldodecan-2,11-dione dioxime(^99mTc-HL91)single-photon emission computed tomography/computed tomography（SPECT/CT）hypoxia imaging in combination with Technetium-99m labeled sestamibi(^99mTc-MIBI)SPECT/CT myocardial perfusion imaging in the evaluation of viable myocardium with different degrees of ischemia and different coronary blood supply areas in comparison with¹⁸F-Fluorodeoxyglucose(¹⁸F-FDG)positron emission tomography/computed tomography（PET/CT）myocardial metabolic imaging as the gold standard in patients with ischemic cardiomyopathy（ICM）.Methods:^99mTc-HL91 hypoxia imaging was performed on the same day as^99mTc-MIBI myocardial perfusion imaging,and ¹⁸F-FDG myocardial metabolism imaging was performed the next day in 66 patients with ICM.The left ventricular myocardium was divided into 17 segments.The myocardial distribution of ^99mTc-MIBI and ^99mTc-HL91 was analyzed.Ischemic myocardial segments were divided into viable and necrotic segments,and the results were compared with those of ¹⁸F-FDG myocardial metabolic imaging.Kappa analysis evaluated the diagnostic consistency between the two physicians or the two diagnostic methods.The diagnostic efficacy of ^99mTc-HL91 hypoxia imaging in the evaluation of viable myocardium with different degrees of ischemia and different coronary blood supply areas in patients with ICM were calculated by four-grid method and receiver operator characteristic（ROC）curve.And the left ventricular ejection fraction（LVEF）values obtained by SPECT/CT imaging and PET/CT imaging were compared by independent sample t-test.Results:（1）1122 myocardial segments in 66 patients with ICM were analyzed.^99mTc-MIBI imaging showed 304 normal and 818 ischemic myocardial segments.Of these,^99mTc-HL91 imaging showed 514 viable and304 necrotic segments,and ¹⁸F-FDG imaging showed 641 viable and 177necrotic segments.The diagnostic consistency of hypoxia or metabolic imaging between two physicians is very good（Kappa=0.913、0.915）.（2）The overall sensitivity,specificity,accuracy,positive predictive value,negative predictive value and area under curve（AUC）of ^99mTc-HL91 hypoxia imaging,in the diagnosis of viable myocardium,were 80.2%,100%,84.5%,100%,58.2%and 0.901 respectively,in good agreement with ¹⁸F-FDG imaging（Kappa=0.637）.（3）The sensitivity,accuracy,negative predictive value and AUC of ^99mTc-HL91 hypoxic imaging in the diagnosis of viable myocardium in severe ischemia with infarction group were significantly higher than those in mild to moderate ischemia group（all P<0.001）,but there were no statistical differences in specificity and positive predictive value between the two groups（all P=1）.（4）There were no statistical differences in the sensitivity,accuracy and AUC of ^99mTc-HL91 hypoxia imaging in the diagnosis of viable myocardium between the left anterior descending artery（LAD）and left circumflex artery（LCX）groups（P=0.121,0.653,0.134）,but were significantly higher than those in right coronary artery（RCA）group（all P<0.001）.There were statistical differences in negative predictive value（LCX>LAD>RCA）between the three groups（P=0.029,<0.001,<0.001）,but there were no statistical differences in specificity and positive predictive value between the three groups（all P=1）.（5）The LVEF values obtained by ^99mTc-MIBI SPECT/CT imaging and¹⁸F-FDG PET/CT imaging were compared in all patients.There was no statistical difference between the two groups（P=0.154）.Conclusions:（1）^99mTc-HL91 imaging in combination with ^99mTc-MIBI perfusion imaging is an effective method for evaluating the survival state of ischemic myocardium.Combination imaging has great clinical value in assessment of viable myocardium particularly in ICM patients with left coronary lesions or severe myocardial ischemia with infarction.However,lower diagnostic value of combination imaging is in patients with mild to moderate ischemia or with right coronary artery lesions.（2）At the same time,combination imaging provides a new and promising method for evaluating myocardial activity for departments with only SPECT/CT and patients with limited financial conditions.