Objective To discuss the impact of an iterative reconstruction algorithm (True X) implemented with point spread function (PSF) on image quality and SUV in 18F-FDG PET, and compare with other reconstruction algorithms.Methods A total of 79 hypermetabolic lesions from 37 cancer patients (23 males, 14 females, age (63.38±15.25) years) were retrospectively studied.The PET images were reconstructed using the following six reconstruction algorithms, including FBP, FBP+TOF, iteration, iteration+TOF, True X, True X+TOF.Paired t test was used for statistical analysis.Results All six reconstruction algorithms showed significant difference in lesion SUVmax.The adoption of PSF increased SUVmax by 15%-16%, and decreased the dispersion of SUV in the liver parenchyma remarkably.Conclusions Lesion SUVmax calculated from different reconstruction algorithms has significant differences.Caution should be taken in using PSF, as it can improve image quality but may also increase lesion SUVmax.

Objective To investigate the potential of 99Tcm-Durarnycin and 99Tcm-RGD in detecting vulnerable plaque in rabbit models.Methods Fifteen healthy New Zealand male rabbits were randomly divided into group A (control group,n =5),group B (stable plaque group,n =5) and group C (vulnerable plaque group,n =5).Animals were injected with 99Tcm-Duramycin and 99Tcm-RGD at the end of 4,8 and 12 weeks.SPECT/CT scanning was performed at 0.5 h post injection.One rabbit was sacrificed at the end of 4 weeks and one at the end of 8 weeks after imaging.The others were sacrificed at the end of 12 weeks after imaging studies.All aortas were collected.Intravascular ultrasound (IVUS) was performed at the end of 8,12 weeks before SPECT/CT scanning.The data was analyzed with paired t test.Results In group A,the aortas had little uptake of the two probes.In group B,the aortas showed obvious radioactive uptake of 99Tcm-Duramycin and 99Tcm-RGD at the end of 8 weeks and 12 weeks,while 99Tcm-Durarnycin gave better display than 99Tcm-RGD.In group C,99Tcm-Duramycin uptake was higher than 99Tcm-RGD uptake in the aorta.The T/NT ratios of 99Tcm-Duramycin and 99Tcm-RGD in group C were 2.14±0.34 and 1.46±0.34 (t=4.072,P＜0.05) at the end of 4 weeks,2.93±0.41 and 1.66±0.22 (t=5.578,P＜0.05) at the end of 8 weeks,3.25±0.29 and 1.81±0.28 (t=19.692,P＜0.05) at the end of 12 weeks.In isolated specimen of group C,the yellow lipid plaque of the intima bulged on the lumen at the end of 12 weeks.IVUS indicated that,at the end of 8 weeks and 12 weeks,the endometrial thickness of group C was (450±104) mm and (767±52) mm (t=44.024,P ＜ 0.05) respectively,and the rates of luminal stenosis were (29.30± 2.81) ％ and (37.98 ±6.41)％ (t =9.226,P＜0.05).Conclusions Both 99Tcm-Duramycin and 99Tcm-RGD may be used to detect vulnerable plaque at early time.99Tcm-Duramycin may detect vulnerable atherosclerotic plaque earlier than 99Tcm-RGD and provide better diagnostic image.

Objective To study the factors affecting the synthesis of 18F-MyoZone,and to evaluate its potential as a myocardial perfusion imaging (MPI) agent in normal Chinese mini-swine.Methods 18F-MyoZone was prepared by substituting the leaving group toluenesulfonyloxy (OTs) from the precursor compound with 18F-fluoride (18F-F-).The conditions affecting the labeling yield were studied by varying the amount of K2CO3 and precursor compound,18F-fluorination reaction time and temperature.PET was performed at 5,30,60 and 120 min post-injection on normal Chinese mini-swine.Results The doses of K2CO3 and precursor,the reaction time and the reaction temperature could affect the labeling yield of 18F-MyoZone,especially K2CO3.The optimized synthetic condition was 1.0 mg K2CO3,2.0 mg mpp2-OTs,20 min reaction time at 90 ℃.The total radio-synthesis time in this condition was 60 min.The uncorrected radiochemical yield was (24.0±5.1) ％.The radiochemical purity was ＞98％.PET imaging showed that 18F-MyoZone had high initial uptake (SUV=8.17± 1.83 at 5 min post-injection) and good retention (SUV =5.78±0.99 at 120 min post-injection) in the heart.The clearance of 18F-MyoZone from liver was very fast.The heart/liver ratios were 3.32,5.31,6.09 and 5.76 at 5,30,60 and 120 min post-injection,respectively.From 5 to 120 min post-injection,the outline of heart was clear and intact.There was almost no interference from the adjacent organs.The quality of PET images was highly satisfactory.Conelusions 18 F-MyoZone has the potential to be a good myocardial perfusion agent.The amount of K2CO3 used could significantly affect the labeling yield of 18F-MyoZone.

Objective To investigate the value of 99Tcm-Duramycin SPCET/CT in the detection of vulnerable plaque (VP) in atherosclerotic (AS) rabbit models.Methods Sixteen New Zealand male rabbits were randomly divided into three groups:group A (sham-operated group,n =4),group B (stable plaque group,n =4) and group C (VP group,n =8).Group A was fed on normal diet,and the other 2groups were fed on cholesterol diet for 12 weeks.Femoral artery dissection sham-operation was done in group A and group B,while balloon-induced abdominal aorta wall injury was produced in group C after 2 weeks'feeding.Animals were injected with 99Tcm-Duramycin (74 MBq/kg) and then SPECT/CT imaging was performed at the end of 4,8,and 12 weeks,respectively.Abdominal aortas were explanted for ex vivo imaging and histological characterization of plaque.The apoptosis index (AI) was calculated.One-way analysis of variance was used to analyze data.Results There was no radioactive uptake by the abdominal aorta in each group at the end of 4 weeks and no uptake in group A and group B at the end of 8 weeks.There was slightly uptake radioactive uptake by the abdominal aorta in group B at the end of 12 weeks and in group C at the end of 8 weeks.There was intense uptake at the lesions of AS rabbits in group C at the end of 12 weeks,and the T/NT value significantly higher than that of the other two groups (3.40±0.22 vs 2.12±0.65,2.68±0.18,F=198.775,P＜0.05).The result was confirmed in the ex vivo imaging of the explanted aorta.The AI of group C was significantly higher than that of group A and B ((25.4±6.32) ％ vs (0±0.02)％,(5.3± 1.97)％,F=70.260,P＜0.05).Conclusions 99Tcm-Duramycin scimigraphy could identify the apoptosis of VP in the rabbit AS models.It is a promising non-invasive method to diagnose AS plaques.

Objective To investigate the feasibility of a novel molecular probe 99Tcm-3P4-RGD2 in evaluating arterial plaque stability after atorvastatin intervention in rabbits with SPECT/CT. Methods Eighteen male New Zealand rabbits were randomly divided into group A (stable plaque), group B (vulnerable plaque), and group C (vulnerable plaque with statin intervention). All rabbits were fed with high-fat food for 12 weeks. After high-fat feeding for two weeks, sham surgery was performed on group A. In the meantime, abdominal aorta injury was performed on group B and group C. After that, rabbits of group C were given oral atorvastatin (2.5 mg·kg-1·d-1). 99Tcm-3P4-RGD2 SPECT/CT imaging was performed on each group at the end of 4, 8 and 12 weeks. T/NT ratios were calculated. Animals were sacrificed at the end of 12 week after imaging studies. The abdominal aortas were collected, imaged with SPECT/CT, and evaluated by pathological HE staining and immunohistochemical analysis. MVD was calculated. Differences among 3 groups were analyzed using one-way analysis of variance. Results There was no significant radioactive uptake in the abdominal aortas of three groups on the 4th week′s imaging. The radioactive uptake in abdominal aortas increased slightly on the 8th week, with the highest radioactive uptake in group B. The radioactivity in abdominal aortas of the 3 groups maintained increasing on the 12th week, with T/NT ratios of 1.579±0.217, 1.873±0.226 and 1.524±0.237, respectively (F=8.984, P<0.05). In ex vivo abdominal aorta images, especially images of group B, radioactivity in lesion sites was higher than that in normal tissue. Accordingly, results of HE staining showed that artery plaques of group A and group C were grade Ⅱ and group B was grade Ⅳ. The MVD of group A, B and C was 8.17±1.17, 15.86±1.07 and 7.17±1.60, respectively (F=9036, P<0.05). Conclusion 99Tcm-3P4-RGD2 SPECT/CT imaging has a high sensitivity in the evaluation of arterial plaque stability after statin intervention in rabbits.

Objective:To evaluate the effect of remote ischemic conditioning (RIC) on left ventricular (LV) myocardial perfusion, myocardial viability, LV remodeling, regional and global LV function serially following acute myocardial infarction (AMI) in Chinese mini-pigs.Methods:AMI was established in 12 Chinese mini-pigs (8 males, 4 females; age: 6-8 months) and they were randomly divided into RIC group ( n=6) and non-RIC group ( n=6). RIC was performed in pigs by blood pressure inflation on the lower limbs for 5 min period and 4 cycles immediately after surgery. A series of myocardial perfusion imaging and gated 18F-fluorodeoxyglucose (FDG) myocardial metabolism PET/CT imaging were performed longitudinally at the 1st, 14th, 28th and 56th days after AMI, and parameters including total perfusion defect (TPD), hibernating myocardium (HM), Scar, left ventricular ejection fraction (LVEF), left ventricular end-diastolic volume (LVEDV), left ventricular end-systolic volume (LVESV), summed motion score (SMS), summed thickening score (STS) and changes of these parameters were obtained. Independent-samples t test and Mann-Whitney U test were used to analyze data. Results:Nine Chinese mini-pigs survived after surgery and were performed imaging. Compared to non-RIC group ( n=4), HM at the 28th ((6.0±2.4)% vs (17.0±4.6)%; t=-4.158), TPD 14th-1st ((-11.8±5.4)% vs 9.0%(4.5%, 15.0%); z=2.449), TPD 28th-1st ((-15.3±3.9)% vs (12.0±3.0)%; t=-10.071), TPD 56th-1st ((-18.0±6.5)% vs 9.0%(4.5%, 12.0%); z=2.449), HM 28th-1st ((-10.5±6.9)% vs (8.3±2.1)%; t=-4.507), HM 56th-1st (-15.0%(-17.5%, -8.5%) vs 2.0%(0%, 7.0%); z=2.449) and LVEDV 14th-1st (-0.5(-2.5, 0) ml vs (13.0±4.4) ml; z=2.470) were reduced in RIC group ( n=5; all P<0.05). Conclusion:RIC can improve myocardial perfusion, delay LV remodeling in the acute stage and salvage hibernating myocardium in the subacute stage and chronic stage.

Objective To evaluate the features of myocardial perfusion imaging (MPI) in patients with homozygous familial hypercholesterolemia (HoFH) and its influence factors.Methods Forty-two consecutive HoFH patients (21 males,21 females;average age:(14.8±8.4) years) were retrospectively enrolled in this study from June 2010 to November 2016.Diagnosis was proved by clinical and chromosome tests,and all patients underwent ATP stress and rest 99Tcm-methoxyisobutylisonitrile (MIBI) SPECT MPI with a two-day protocol.Summed stress score (SSS) and summed rest score (SRS) were acquired,and summed difference score (SDS;SSS-SRS) was calculated.Relations between SSS,SRS,SDS and age,lipid profile were analyzed.Two-sample t test,x2 test,multiple linear regression analysis and multivariate logistic regression were used to analyze the data.Results There were 24 patients with positive MPI results (SSS≥1),and females (76.2％,16/21) showed more positive MPI results than males (38.1％,8/21;x2=6.22,P＜0.05).Eighteen patients had negative MPI results.There were 6,8,10 patients with MPI positive results in ＜ 10 years group (n =14),10-18 years group (n =14) and ≥ 19 years group,respectively (x2=2.33,P＞0.05).Positive electrocardiograph (ECG) in ATP stress test was observed in 9 females (42.9％,9/21) and 3 males (14.3％,3/21;x2 =4.20,P＜0.05).Sixty-three (8.8％,63/714) abnormal myocardial perfusion segments (SSS≥ 1) were found,which was mainly (60.3％,38/63) distributed in myocardial regions supplied by left anterior descending branch (LAD).SSS was positively correlated with age and high density lipoprotein cholesterol (HDLC).SRS,SDS were positively correlated with HDLC and age respectively.Multivariate logistic regression analysis indicated that the female was the only independent risk factor to predict positive MPI (odds ratio=5.2,95％ CI:1.363-19.774).Conclusions In HoFH patients,abnormal myocardial perfusion had a rising trend with age increasing.Female patients are more likely to have abnormal MPI.Abnormal myocardial perfusion segments are mainly located in myocardial regions supplied by LAD.Age and gender are influence factors of abnormal MPI in HoFH patients.

Objective To evaluate 18F-fluorodeoxyglucose (FDG) PET/CT in the rabbit model of vulnerable plaques by correlation with 99Tcm-Arg-Gly-Asp (RGD) SPECT/CT imaging,lipid levels,pathological and immunohistochemical results.Methods Sixteen male New Zealand white rabbits were randomly divided into normal diet group (group A,n =4),stable plaque group (group B,n =4) and vulnerable plaque group (group C,n =8) using completely random grouping method.The animals were given abdominal aorta sham operation (groups A and B) or balloon injury of the abdominal aorta (group C) 2 weeks after feeding.Animals were injected with 18F-FDG and 99Tcm-RGD respectively at the end of 4,8 and 12 weeks.PET/CT was performed at 1,2 and 3 h post-injection.SPECT/CT was performed at 30 min post-injection.One rabbit was sacrificed at the end of 4 and 8 weeks after imaging studies,respectively.The others were sacrificed at the end of 12 weeks after imaging studies.All abdominal aortas were harvested.Pathology and immunohistochemistry analysis were performed.The data were analyzed by one-way analysis of variance and Pearson correlation analysis.Results There was no uptake in any group at 4th week and no uptake in group A or group B at 8th week.There was mild uptake in group B at 12th week and group C at 8th week.There was intense uptake in group C at 12th week,whereas both mean standardized uptake value (SUVmean) and maximum standardized uptake value (SUVmax) were significantly higher than the other two groups (F values:7.952,14.279,both P＜0.05).In group C,SUVmax(0.43±0.08,0.68±0.06,1.74±0.63) and SUV (0.37±0.03,0.56±0.03,1.26+0.23) had significant difference at 3 h post-injection for imaging at 4th,8th and 12th week (F values:10.939,39.747,both P＜0.05).At 12th week,there was a strong correlation between the uptake of 18 F-FDG and target/non-target (T/NT) ratio of 99Tcm-RGD in all groups(r values:0.748,0.709,both P＜0.05).Histopathology results showed that the plaques had rich macrophages and a small amount of smooth muscle cells in group C,little macrophages in group B,while no macrophages in group A.Conclusion 18F-FDG PET/CT might be an effective noninvasive method for early assessment of aortic vulnerability to atherosclerotic plaque.

Objective:To evaluate the predictive value of stress+ rest gated myocardial perfusion imaging (G-MPI) in assessing all-cause mortality risk in patients with familial hypercholesterolemia (FH).Methods:From June 2010 to March 2022, 72 patients (39 males, 33 females; age (21.1±12.3) years) who diagnosed with FH clinically and genetically and underwent stress+ rest G-MPI in Beijing Anzhen Hospital, Capital Medical University were retrospectively followed up. Image analysis was performed using the 17-segment 5-point method to obtain left ventricular myocardial perfusion and functional parameters. Patients were followed for all-cause mortality events, and predictors associated with the risk of all-cause mortality were analyzed using Cox regression. The efficiencies of predictors were evaluated by ROC curve analysis, and the Kaplan-Meier method and log-rank test were used to compare the differences in the incidence of all-cause mortality in different groups of patients with FH. Independent-sample t test or Mann-Whitney U test was used to analyze the data. Results:The follow-up time of 72 patients was 7(4, 10) years, and all-cause death occurred in 16(22.2%) patients during the follow-up period. There were statistically significant differences in total cholesterol (TC), low density lipoprotein cholesterol (LDLC), summed stress score (SSS), summed rest score (SRS), summed difference score (SDS), stress end-systolic volume (SESV), stress ejection fraction (SEF), rest end-diastolic volume (REDV), rest end-systolic volume (RESV) and rest ejection fraction (REF) between the death group and the survival group ( t values: from -2.65 to 4.47, z values: from -3.43 to -1.98, all P<0.05). Cox regression analysis showed that SDS (hazard ratio ( HR)=1.337, 95% CI: 1.114-1.604, P=0.002), SESV ( HR=1.019, 95% CI: 1.008-1.030, P<0.001) and LDLC ( HR=1.355, 95% CI: 1.049-1.749, P=0.020) were independent predictors associated with the risk of all-cause mortality in patients with FH. The optimal cut-off value of SESV for predicting mortality in patients with FH determined by ROC curve analysis was 35.5 ml, with the AUC of 0.701 (95% CI: 0.517-0.885). The incidence of all-cause mortality in the group with SESV≥35.5 ml was significantly higher than that in the group with SESV<35.5 ml (28.6% vs 6.9%; χ2=5.15, P=0.023). Conclusion:Stress+ rest G-MPI is an important imaging method for all-cause mortality risk assessment in patients with FH, and SDS, SESV and LDLC are important factors in predicting mortality in patients with FH.

Objective:To serially characterize the myocardial perfusion, myocardial hibernation and left ventricular (LV) function as well as LV remodeling in progressive coronary artery stenosis in Chinese mini-pigs.Methods:In 8 Chinese mini-pigs (5 males, 3 females; age: 10 months), chronic progression of coronary stenosis and finally occlusion was established using Ameroid constrictor implantation at the 1 cm below the bifurcation of the first diagonal branch of the left anterior descending (LAD) artery. Serial gated 99Tc m-methoxyisobutylisonitrile(MIBI) SPECT/CT, gated 18F-FDG PET/CT imaging and coronary angiography (CAG) were performed before surgery and at the 1st, 4th and 8th week after surgery. Longitudinally, total perfusion defect (TPD), LV ejection fraction (LVEF), LV end-diastolic volume (LVEDV), LV end-systolic volume (LVESV), summed motion score (SMS), summed thickening score (STS) and hibernating myocardium (HM) were analyzed. Repeated measures analysis of variance, Kruskal-Wallis rank sum test and Bonferroni correction method were used to analyze data. Results:One mini-pig died of infection after the Ameroid constrictor implantation. In the remaining 7 mini-pigs, TPD was progressively increased with time prolonged (0, 12.0%(0, 33.0%), (41.1±23.7)% and (49.3±24.5)%; H=17.03, P=0.001); Compared with HM before the surgery (100%), HM was gradually reduced from the 1st (21.0%(6.0%, 100%)) to the 4th (18.0%(3.0%, 33.0%)) week after surgery, and then increased to the 8th week after surgery ((23.0±15.4)%; H=13.09, P=0.004), but there was no significant difference between the 1st and 4th week, or between the 4th and 8th week after surgery (both P>0.05 (Bonferroni correction method)). Accordingly, LVEF gradually decreased ((73.7±8.4)%, (63.7±19.1)%, (53.7±14.6)% and (49.9±15.4)%; F=6.22, P=0.004). LVEDV (9.0(6.0, 21.0), (31.4±16.3), (32.9±17.4) and (36.4±17.5) ml; H=8.58, P=0.035)and LVESV ((3.8±3.2), (15.9±15.3), 12.0(10.0, 17.0)and (19.3±10.9) ml; H=10.51, P=0.015) gradually increased. SMS and STS continuously increased as well ( H values: 16.49, 13.33, P values: 0.001, 0.004). Conclusions:With the progression of coronary artery stenosis to occlusion, myocardial perfusion is gradually decreased, while the global and regional LV function, LV remodeling are gradually aggravated, and HM is gradually reduced. After the chronic coronary artery occlusion, myocardial perfusion has a trend to be improved and HM is gradually recovered.