Radionuclide MPI is an important noninvasive modality for the diagnosis of coronary artery disease.The current clinically useful MPI tracers,201Tl and 99Tcm labeled agents,have limitations.Some known ligands bound with 99TcmN core might be promising MPI agents because of their high chemical stability.This review summarizes the structure,biodistribution and imaging characteristics of the 99TcmN core labelled MPI tracers with emphasis on several agents having promising prospects for future applications.

Objective To explore the relationship between hypothyroidism and myocardial injury in patients with idiopathic dilated cardiomyopathy (IDC) by 99Tcm-MIBI SPECT/18 F-FDG PET and late-gadolinium enhancement cardiac magnetic resonance imaging (cMRI-LGE).Methods Sixty-three consecutive patients (42 males and 21 females,(52±11) years) with IDC were enrolled from October 2010 to December 2012.Serum TT3,TT4,FT3,FT4 and TSH were determined using a fully automated chemiluminescence immunoassay.All patients underwent 99Tcm-MIBI myocardial perfusion SPECT/18F-FDG myocardial metabolism PET imaging and cMRI-LGE.Seventeen segments model was used for segmental analysis.Patterns of perfusion/metabolism were classified as normal,mismatch,mild-to-moderate match and complete match.cMRI-LGE was classified into 3 categories (non-LGE,mid-wall LGE and transmural LGE).x2 test was used for data analysis.Results All patients were divided into euthyroid group (n =53) and hypothyroidism group (n =10) according to the levels of serum thyroid hormones.The percentage of normal perfusion/metabolism segments in the euthyroid group was apparently higher than that in the hypothyroidism group:71.8％ (647/901) vs 57.6％ (98/170),x2 =13.50,P＜0.001 ; whereas the percentage of perfusion/metabolism mismatch segments in the euthyroid group was significantly lower than that in the hypothyroidism group:17.8％ (160/901) vs 31.2％ (53/170),x2=16.20,P＜0.001.The euthyroid group had a higher percentage of non-LGE segments (88.0％ (793/901) vs 69.4％ (118/170),x2 =35.70,P＜0.001) and a lower percentage of mid-wall LGE segments (4.8 ％ (43/901) vs 24.1％ (41 / 170),x2 =74.70,P＜ 0.001) compared to hypothyroidism group.Conclusions Hypothyroidism has a detrimental effect on myocardium.99Tcm-MIBI SPECT/18F-FDG PET imaging is sensitive in detecting viable/ischemia myocardium,and cMRI-LGE is good at detecting moderate fibrosis.Combining SPECT/PET imaging and cMRI-LGE for assessing myocardial injury would provide more comprehensive information.

Objective To explore the relationship between myocardial glucose metabolism in the right heart and cardiac function in patients with idiopathic dilated cardiomyopathy (IDCM).Methods From October 2010 to May 2013,64 consecutive patients (45 males,19 females; mean age:(53 ± 12) years) with IDCM were enrolled in this study.All patients underwent 18F-FDG myocardial PET imaging,late-gadolinium enhancement cardiac MRI (cMRI-LGE) and UCG.TrueD software was used to determine the SUVmax in right (SUV-R) and left (SUV-L) ventricular free wall,and the ratio of SUV-R to SUV-L (SUV-R/L) was calculated.The cMRI-LGE was used to evaluate LVEF,RVEF and LGE in left heart.Pulmonary artery systolic pressure (PASP) was measured by UCG.Two-sample t test and Pearson correlation analysis were used to analyze the data.Results Both SUV-R and SUV-R/L had negative correlation with LVEF (r=-0.48,-0.33; both P＜0.01) and also with RVEF (r=-0.45,-0.44; both P＜0.01).SUV-R/L positively correlated with PASP (r =0.58,P＜0.01).SUV-R/L of patients with and without LGE were statistically different (0.45±0.18 vs 0.36±0.12; t=2.50,P＜0.05).SUV-R and SUV-L of patients with LGE were 2.0±0.9 and 4.7±1.6,and those of patients without LGE were 1.7±0.9 and 5.0±2.8.Both differences of SUV-R and SUV-L between the two groups were not statistically significant (t=0.54 and 0.63,both P＞0.05).Conclusions Myocardial glucose metabolism in right heart is closely correlated with left and right ventricular function.The assessment of 18F-FDG uptake in right heart by PET imaging is potentially useful for evaluation of the severity and prognosis in IDCM patients.

Objective: To investigate the relationship between right ventricular (RV) glucose metabolism by18F-fludeoxyglucose positron emission tomography (18F-FDG PET) and right heart function in patients with dilated cardiomyopathy (DCM).
Methods: The18F-FDG PET imaging was performed in 34 consecutive DCM patients, with the reference of Herrero method, the corrected RV standard uptake value (cRVSUV), corrected left ventricular standard uptake value (cLVSUV) and the ratio of RV to LV SUV (cR/L) were obtained. And all 34 patients received cardiac magnetic resonance imaging (cMRI) examination within 7 days, the left ventricular ejection fraction (LVEF) and RVEF were automatically calculated with Simpson’s principle. The pulmonary arterial systolic pressure was measured by echocardiography.
Results: The corrected cRVSUV and cR/L by18F-FDG PET were negatively related to RVEF by cMRI, (r=-0.513, P<0.01) and (r=-0.463,P<0.01) respectively, and meanwhile, the corrected cRVSUV and cR/L were also negatively related to LVEF, (r=-0.387,P<0.01 andr=-0.362,P<0.01) respectively.
Conclusion: Increased RV glucose metabolism closely related to RV dysfunction, the18F-FDG uptake value by PET might be used as an index for assessing the right heart function and prognosis in DCM patients.

Objective: To explore the relationship between septal myocardial metabolism and left ventricular mechanical synchronization in patients with dilated cardiomyopathy (DCM) and left bundle branch block (LBBB) by gated 18F-FDG myocardial metabolic imaging.
Methods: A total of 20 consecutive patients diagnosed for DCM with LBBB from 2010-10 to 2013-05 were enrolled, there were 11 male and 9 female at the mean age of (54±11) years. All patients received gated 18F-FDG myocardial metabolic PET imaging. TrueD software was used to determine the maximal standardized 18F-FDG uptake value (S-SUVmax) and the average standardized uptake value (S-SUVavg). QGS software was applied to conduct left ventricular phase analysis and to detect the cardiac function, left ventricular bandwidth (BW), standard deviation of bandwidth (SD), left ventricular end-diastolic volume (LVEDV), LVESV and LVEF. The relationship between 18F-FDG uptake in septal myocardium with the indexes of phase analysis and the indexes of cardiac function was analyzed.
Results: S-SUVmax and S-SUVavg were respectively negatively related to BW (r=-0.44, P<0.05 and r=-0.48, P<0.05);they were also respectively negatively related to SD (r=-0.57, P<0.01 and r=-0.51, P<0.05). While S-SUVmax and S-SUVavg were not really related to LVEDV, LVESV and LVEF, all P>0.05.
Conclusion: In patients of DCM with LBBB, reduced septal myocardial metabolism was closely related to left ventricular mechanical synchronization, gated 18F-FDG myocardial metabolic PET imaging may simultaneously detect both functions, which was important for prognostic evaluation and therapeutic monitoring in clinical practice;phase analysis.