Multimodality MR Imaging In Determination Of Myocardial Viability (Experimental And Clinical Study Compared With SPECT, PET And Echocardiography)

Objective To evaluate the value of multimodality MR imaging in detecting of myocardial viability.Materials and Methods 25 pigs of chronic myocardium ischemia model underwent multimodality MR imaging before and after 1~2 month making model. The multimodality MR imaging include: morphology scanning, cine MRI, myocardial perfusion and viability imaging. The range of myocardial ischemia and necrosis in MRI was compared with pathology and coronary angiography to understand its accurate.Results 20 pigs completed all examination successfully. Morphology scanning detected thinning in lateral wall of left ventricle in 3 pigs. Stress cine MRI detected normal wall motion in 11(11/20) pigs. 11 segments of 7(7/20) pigs were found hypokinetic, 19 segments of 4(4/20) pigs were found akinetic in lateral wall of left ventricle in rest. Dobutamine stress cine MRI detected increased regional motion of the lateral wall in hypokinetic segments, but the lateral wall remained akinetic in 19 segments. Myocardial perfusion scanning detected 64 (20%) segments ischemia. Delayed hyperenhancement was observed in 25 (7.81%)segments, of which 2 segments showed 26-50% extent of endocardium infarction, 5 segments showed 51-75% extent of endocardium infarction, 18 segments showed transmural extent infarction.The total segments of necrosis was 27 (8.44%) in pathology, of which 1 segments showed 26-50% extent of endocardium infarction, 6 segments showed 51-75% extent of endocardium infarction, 20 segments showed transmural extent infarction .There were no significant difference between pathology and viability MR imaging ( p =0.5), but showed significant difference between pathology and cine MR imaging ( p=0.008).Using the result of pathology as gold standard, sensitivity, specificity, positive predictive value, negative predictive value and total consistent rate were 70.4%, 100%, 100%, 97.3% and 97.5% respectively for cine MR imaging; and 92.6%, 100%, 100%, 99.3% and 99.4% respectively for viability MR imaging. Compared with pathology, the kappa value was 0.813 in cine MR imaging, 0.958 in viability MR imaging.Conclusion Analysis wall motion capability semiquantitatively can't determine small infarct myocardium or endocardium infarct myocardium effectively. Combination of myocardial perfusion and viability MR imaging can increase the detection of small endocardium infarction which mix in normal myocardium. Multimodality MR imaging technique can increase the detection rate and accuracy of myocardial viability obviously; it has high concordance with physiology.No.2 Multimodality MR Imaging in determination of myocardial viability (an experimental study compared withSPECT ,PET and echocardiography)Objective To evaluate the diagnostic value for myocardial viability by using various imaging methods.Methods Chronic myocardial ischemia animal model in 10 pigs were established and underwent multimodality MR imaging,l8F-fluorodeoxyglucose positron emission tomography (PET), 20lTl single-photon emission computed tomography (SPECT) and low-dose dobutamine echocardiography(LDDSE) before and after 1 to 2 month modeling, respectively. The size of myocardial ischemia and necrosis was judged and compared with pathology result to assess the sensitivity and specificity of various methods.Results 7 pigs completed all examination successfully. At rest-cine MRI, 10(8.93%) segments were akinetic ,6(5.36%) segments were hypokinetic. During dobutamine infusion, 10(8.93%) segments were akinetic which determined as infarct segments . Perfiision was abnormal in 34(30.35%) segments. Delayed hyperenhancement was observed in 12(10.71%) segments, of which 1 segments showed 1-25% extent of endocardium infarction, 11 segments showed transmural extent infarction. PET showed 17(15.18%) segments of myocardial necrosis. SPECT showed 9(8.04%) segments of myocardial necrosis. At rest LDDSE, 8(7.14%) segments were akinetic, 9(8.04%) segments were hypokinetic. During dobutamine infusion, 8(7.14 % ) segments were akinetic. Triphenyl tetrazolium chloride(TTC) determined 14(12.50%) segments of necrosis, of which 3 segments showed 1-25% extent of endocardium infarction, 11 segments showed transmural extent infarction.. Necrosis segments determined by PET significantly higher than contrast-enhanced MR imaging (p=0.0253JCappa=0.S02Z) and cine MRI ,/?=0.0082, Kappa=0.7079), It also higher than TTC(p=0.0833, Kappa=0.8$79), but had no significant statistic difference. Necrosis segments determined by SPECT significantly lower than TTC (p=0.0253, Kappa=0.7590). Necrosis segments determined by cine MR significantly lower than TTC (p=0.0455, Kappa=0.S\00). Necrosis segments determined by contrast-enhanced MRI had no significant statistic difference with TTC (p=0.\573, Kappa=0.9\30). Necrosis segments determined by LDDSEsignificantly lower than TTC (p=0.0\40, Kappa=0.7'000). Using TTC as gold standard, the sensitivity and specificity of cine MRI, contrast-enhanced MRI, PET,SPECT and LDDSE in the determination of unviable myocardium were 71.43 %, 100% ;85.71 %, 100 %; 100 % ,96.94 % ;64.29%, 100% and 57.10%, 100%,respectively. Conclusion Cardiac MRI can combine morphology, function and perfusion to determine viable myocardium, delineate the location and degree of necrosis myocardium clearly, demonstrate wall motion of left ventricular directly and cheaper than PET, MRI has high consistency with PET and pathology result. PET slightly overestimate extent of necrosis myocardium and can't distinguish transmural necrosis from subendocardial necrosis. Coronary angiography can detect stenosis or obstruction of coronary artery, it also observe wall motion real-time, but it can't show impairment of microcirculation and perfusion of myocardium directly. 201Tl single-photon emission computed tomography and low-dose dobutamine echocardiography underestimate myocardial viability, can't show extent of infarction exactly.Part II Clincial Experimental StudyMultimodality MR Imaging in determination of myocardial viability (a clinical experimental study compared with SPECT, PETand echocardiography)Objective To evaluate the diagnostic value of myocardial viability in patients with chronic ischemic heart disease by using various imaging methods.Methods 29 patients(23 man and 6 women,mean age 59.72 years[SD 9.27]) who suspected coronary artery disease underwent multimodality MR imaging, 18F-fluorodeoxyglucose positron emission tomography (PET), 2OIT1 single-photon emission computed tomography (SPECT) andmyocardial contrast echocardiography(MCE) before revascularization. In a 16-segment model, the size of myocardial ischemia and necrosis was judged. Compared MRI viability scanning result with PET result to assess the sensitivity and specificityResults 18 patients(15 man and 3 women) completed all examination successfully. Coronary angiography detected 1 artery disease in 7 patients, 2 arteries disease in 2 patients, 3 arteries disease or above in 7 patients, normal coronary arteries in 2 patients. Morphology scanning using MRI HASTE sequence deteced various extent hyper-intensity thrombus located in endocardium of apex. Ejection fraction, stroke volume, cardiac output measured by cine MRI significantly lower than which measured by ultrasound(ï¿¡><0.05), end-diastolic volume and end-systole volume measured by cine MRI higher than which measured by ultrasound, but had no significant statistic difference.At rest-cine MRI, 11(3.82%) segments were paradoxical motion, 54(18.75%) segments were hypokinetic,223(77.43%) segments were normal. Perfusion was abnormal in 136(47.22%) segments. Delayed hyperenhancement was observed in 73(25.35%) segments, of which 23 segments showed 1-25% extent of endocardium infarction, 20 segments showed 26-50% extent of endocardium infarction, 11 segments showed 51-75% extent of endocardium infarction, 19 segments showed transmural extent infarction. 215(74.65%) segments showed no infarction which determined as viable myocardium. Myocardial perfusion of SPECT showed 78(27.08 %) segments of myocardial ischemic,of which 47(16.32%) segments showed defect, 10(3.47%) segments showed rarefaction, 21(7.29%) segments showed obviously rarefaction. 210(72.92%) segments showed normal. 18F-FDG PET metabolism examination showed 76(26.39%) segments defect which defined as myocardial necrosis, 212(73.61%) segments showed normal.4 patients with different hypokinetic of left ventricle and2 patients with paradoxical motion of left ventricle deteced by M type ultrasound. MCE myocardial perfusion detected 69(23.96%) segments showed reduced opacification, 49(17.01%) segments showed minimal or absent opacification, 170(59.03%) segments showed homogenous opacification. Ischemic segments detected by MRJ significantly higher than which deteced by MCEOp=0.000). Ischemic segments detected by MRI significantly higher than which deteced by SPECT(p=0.002). Ischemic segments detected by MCE significantly higher than which deteced by SPECT (p=0.026).Necrosis segments determined by delayed enhancement MRI lower than PET but had no significant statistic difference(fH).674). Using PET as gold standard, the sensitivity,specificity, positive predictive value negative predictive value and total coincidence of delayed enhancement MRI in the determination of unviable myocardium were 98.6 % ,100 % ,100%,96.1%, and 98.9%,respectively. Kappa value of delayed enhancement MRI and PET was 0.973.Conclusion Cardiac MRI can combine morphology, function and perfusion to determine viable myocardium, delineate the location and extent of necrosis myocardium and mural thrombosis clearly, demonstrate wall motion of left ventricular directly and measure function of left ventricle, quantified display thickenss of end-diastolic and end-systole and thickening of wall. Delayed enhancement MRI had no significant statistic difference with PET in detect myocardial infarction. MRI has high consistency with PET result and cheaper than PET. Myocardial perfusion- metabolism is the most reliable method to evaluate myocardial viability now. It often regarded as gold standard when compare with other method of detect myocardial vability. But PET has low spatial resolution which can't distinguish transmural necrosis from subendocardial necrosis and can't demonstrate wall motion of left ventricular directly. MCE...