Objective:To optimize the image quality of PET/CT following 90Y-selective internal radiation therapy ( 90Y-SIRT) using block-sequential regularized expectation maximization (BSREM) reconstruction algorithm, and to evaluate its impact of different β values on image quality and quantitative analysis. Methods:A retrospective study was conducted on 8 male patients with hepatic tumors (age: 62(52, 71) years) treated at Beijing Tsinghua Changgung Hospital, School of Clinical Medicine, Tsinghua Medicine Tsinghua University, between June 2024 and January 2025. All patients were treated with 90Y resin microspheres (2.6(0.9, 3.6)GBq) and underwent post-treatment 90Y PET/CT liver imaging. Imaging data were reconstructed using BSREM with different noise penalty weighting factors ( β values: 0, 300, 1000, 1500, 2500, 3500, 4000, 6000, 8000, 10000). Visual assessment was independently performed by two nuclear medicine physicians, using a 4-point scale (1=worst, 4=best). The mean score was considered as the final score. The consistency of the 2 reviewers was calculated and analyzed by Kappa test. Visual scores of different β value groups were compared by Friedman test. The β value demonstrating highest mean score and optimal consistency was selected as the optimal. Quantitative analysis was performed using MIM software to calculate the maximum absorbed dose ( Dmax) and the mean absorbed dose ( Dmean) for tumor, normal liver, and whole liver regions, and the CV was used to evaluate the impact of β values. Results:The visual assessment consistency of reviewers in 3 β value groups (0, 3500, 6000) were the highest (7/8) (all kappa=0.88, all P<0.05). Visual scores of the 10 β value groups were significantly different ( χ2=28.74, P<0.001), and the visual scores of 2 β value groups (3500, 4000) were the highest, both of which were 4.0(4.0, 4.0). Overall, visual assessment identified β=3500 as the optimal. Quantitative analysis revealed that, (1) Dmax in all regions (tumor, normal liver, whole liver) decreased with the increasing β values, stabilizing when β>1000 ( CV 56%-67%); (2) Dmean remained stable across different β values ( CV 0.04%-5.00%). Conclusions:In BSREM reconstruction, β=3500 is the optimal parameter for improving 90Y-PET image quality. β values significantly affect Dmax (stabilizing at β > 1000), but have no significant impact on Dmean, suggesting that reconstruction parameters primarily influence dose distribution morphology rather than average dose assessments.

Objective:To optimize the image quality of PET/CT following 90Y-selective internal radiation therapy ( 90Y-SIRT) using block-sequential regularized expectation maximization (BSREM) reconstruction algorithm, and to evaluate its impact of different β values on image quality and quantitative analysis. Methods:A retrospective study was conducted on 8 male patients with hepatic tumors (age: 62(52, 71) years) treated at Beijing Tsinghua Changgung Hospital, School of Clinical Medicine, Tsinghua Medicine Tsinghua University, between June 2024 and January 2025. All patients were treated with 90Y resin microspheres (2.6(0.9, 3.6)GBq) and underwent post-treatment 90Y PET/CT liver imaging. Imaging data were reconstructed using BSREM with different noise penalty weighting factors ( β values: 0, 300, 1000, 1500, 2500, 3500, 4000, 6000, 8000, 10000). Visual assessment was independently performed by two nuclear medicine physicians, using a 4-point scale (1=worst, 4=best). The mean score was considered as the final score. The consistency of the 2 reviewers was calculated and analyzed by Kappa test. Visual scores of different β value groups were compared by Friedman test. The β value demonstrating highest mean score and optimal consistency was selected as the optimal. Quantitative analysis was performed using MIM software to calculate the maximum absorbed dose ( Dmax) and the mean absorbed dose ( Dmean) for tumor, normal liver, and whole liver regions, and the CV was used to evaluate the impact of β values. Results:The visual assessment consistency of reviewers in 3 β value groups (0, 3500, 6000) were the highest (7/8) (all kappa=0.88, all P<0.05). Visual scores of the 10 β value groups were significantly different ( χ2=28.74, P<0.001), and the visual scores of 2 β value groups (3500, 4000) were the highest, both of which were 4.0(4.0, 4.0). Overall, visual assessment identified β=3500 as the optimal. Quantitative analysis revealed that, (1) Dmax in all regions (tumor, normal liver, whole liver) decreased with the increasing β values, stabilizing when β>1000 ( CV 56%-67%); (2) Dmean remained stable across different β values ( CV 0.04%-5.00%). Conclusions:In BSREM reconstruction, β=3500 is the optimal parameter for improving 90Y-PET image quality. β values significantly affect Dmax (stabilizing at β > 1000), but have no significant impact on Dmean, suggesting that reconstruction parameters primarily influence dose distribution morphology rather than average dose assessments.

Surgery is the main treatment for patients with hepatocellular carcinoma to achieve long-term survival. However, only 20%-30% of patients can receive radical surgery. How to optimize the surgery oriented comprehensive treatment strategy and enable patients to successfully downstage to surgery are key issues to be solved in hepatocellular carcinoma treatment in China. Selective internal radiation therapy with yttrium-90 microspheres ( 90Y-SIRT) has strong ability of tumor killing, and it is reported that 90Y-SIRT is an ideal downstaging and bridging therapy for hepatocellular carcinoma, due to its superior downstaging efficacy compared with transarterial chemoembolization. Based on the introduction of characteristics of 90Y-SIRT, the authors review the clinical research progress of 90Y-SIRT in the preoperative downstaging and bridging treatment of hepatocellular carcinoma before liver transplantation, and discuss 90Y-SIRT-based conversion strategy. The 90Y-SIRT has shown syner-gistic effect with targeted therapy and immunotherapy, and will have a broad application prospect in downstaging and conversion therapy in the future.

Surgery is the main treatment for patients with hepatocellular carcinoma to achieve long-term survival. However, only 20%-30% of patients can receive radical surgery. How to optimize the surgery oriented comprehensive treatment strategy and enable patients to successfully downstage to surgery are key issues to be solved in hepatocellular carcinoma treatment in China. Selective internal radiation therapy with yttrium-90 microspheres ( 90Y-SIRT) has strong ability of tumor killing, and it is reported that 90Y-SIRT is an ideal downstaging and bridging therapy for hepatocellular carcinoma, due to its superior downstaging efficacy compared with transarterial chemoembolization. Based on the introduction of characteristics of 90Y-SIRT, the authors review the clinical research progress of 90Y-SIRT in the preoperative downstaging and bridging treatment of hepatocellular carcinoma before liver transplantation, and discuss 90Y-SIRT-based conversion strategy. The 90Y-SIRT has shown syner-gistic effect with targeted therapy and immunotherapy, and will have a broad application prospect in downstaging and conversion therapy in the future.

Objective:To investigate the application value of renal depth correction by the integrated CT in glomerular filtration rate (GFR) determination by 99Tc m-diethylene triamine pentoacetic acid (DTPA) renal dynamic imaging for patients with hydronephrosis. Methods:A total of 338 patients (191 males, 147 females, age (49.6±14.5) years) in Beijing Tsinghua Changgung Hospital from April 2016 to June 2019 with different degrees of hydronephrosis were respectively analyzed. Patients were divided into groups of normal-mild, normal-moderate, normal-heavy, mild-mild, mild-moderate, mild-heavy, moderate-moderate, moderate-heavy and heavy-heavy according to the degree of bilateral hydronephrosis. The renal depth was measured by the integrated CT method and the routine method, and the absolute value of bilateral renal depth difference in normal-mild, normal-moderate and normal-heavy groups was calculated by the 2 methods. Based on the renal depth measured by the 2 methods, the single renal GFR was measured by 99Tc m-DTPA dynamic renal imaging Gates method and compared between the 2 methods. Total GFR measured by the 2 methods were compared with estimated GFR (eGFR). One-way analysis of variance analysis, paired t test, and Pearson correlation analysis were used. Results:For the integrated CT measurements, the absolute value of bilateral renal depth difference in normal-mild, normal-moderate and normal-heavy groups were significantly different ((0.39±0.24), (1.16±0.65) and (1.00±0.90) cm; F=15.241, P<0.05). The renal depth and the single renal GFR measured by the integrated CT method were higher than those measured by the routine method ( t values: 16.06-19.78, 14.27-17.23, all P<0.05) in the kidneys with normal, mild, moderate and heavy hydronephrosis. There were significant differences between the total GFR measured by the routine method and eGFR in all groups ( t values: from -8.178 to 5.879, all P<0.05); however, in the integrated CT method, except that the total GFRs in moderate-heavy group and heavy-heavy group were overestimated ( t values: 3.035 and 11.247, both P<0.05), there were no significant differences between the total GFR ((111.57±17.37), (103.71±15.22), (79.79±12.62), (100.33±18.49), (100.28±15.43), (84.09±20.72) and (74.14±14.57) ml·min -1·1.73 m -2) and eGFR ((109.16±12.81), (103.20±13.26), (78.60±14.12), (100.98±15.20), (99.89±14.05), (84.61±20.24) and (73.44±14.57) ml·min -1·1.73 m -2) in normal-mild, normal-moderate, normal-heavy, mild-mild, mild-moderate, mild-heavy and moderate-moderate groups ( t values: from -0.301 to 1.948, all P>0.05). The total GFR measured by the 2 methods were significantly correlated with eGFR in 338 patients with hydronephrosis ( r values: 0.888 and 0.928, both P<0.01). Conclusion:Compared with the routine method, except for the moderate-heavy group and heavy-heavy group, renal depth correction by the integrated CT may have greater clinical significance in GFR measurement by renal dynamic imaging for patients with hydronephrosis.

Objective To prospectively compare cadmium-zinc-telluride (CZT) SPECT gated myocardial perfusion imaging (GMPI),conventional SPECT MPI and cardiac MRI for the assessment of left ventricular volume and ejection fraction in patients with heart failure.Methods From July 2016 to October 2016,a total of 35 patients (27 males,8 females,average age:(52.7±14.9) years) with heart failure were consecutively included.All patients underwent CZT SPECT GMPI,conventional SPECT GMPI and cardiac MRI within 7 d.LVEDV,LVESV and LVEF of three imaging modalities were calculated.One-way analysis of variance,Pearson correlation analysis and Bland-Altman analysis were used.Results CZT SPECT showed excellent correlation with conventional SPECT for LVEDV,LVESV and LVEF (r values:0.983,0.986 and 0.910,respectively;all P＜0.001).Bland-Altman analysis revealed good agreement between CZT SPECT and conventional SPECT for LVEDV,LVESV and LVEF.The correlation between CZT SPECT and cardiac MRI for LVEDV,LVESV and LVEF were all significant (r values:0.864,0.896 and 0.836,respectively;all P＜0.001).Compared with cardiac MRI,CZT SPECT showed systemic underestimation of LVEDV and LVESV and good agreement of LVEF by Bland-Altman analysis.Conclusions CZT SPECT has high clinical value for patients with heart failure.Despite underestimating LVEDV and LVESV,it correlated well with cardiac MRI.It also has a good agreement with conventional SPECT on left ventricular volume and LVEF.

Objective: To assess the effect of coronary collateral circulation (CCC) on myocardial viabilityin patients with chronic total occlusion of left anterior descending (LAD) artery. Methods: A total of 101 consecutive patients with confirmed diagnosis of total LAD occlusion in our hospital were enrolled. Rest 99mTc-MIBISPECT myocardial perfusion and 18F-FDG PET were performed, in addition all patients received coronary angiography (CAG) at 3 months front and back. Both images were reconstructed in the same machine and QPS software was used to obtain the summed rest score (SRS), abnormal resting total perfusion defect (TPD), viable and non-viable myocardium, LVEDV, LVESV and LVEF in relevant patients. Based on CAG result, the patients were divided into 2 groups: CCC group, n=39 and No CCC group, n=62; according to existing old myocardial infarctionand location of LAD occlusion, the patients were further divided into 4 subgroups. The above parameters were compared among different groups. Results: There were 86 male and 15 female patients with the mean age at (59.92±11.43) years. Relevant parameters in CCC group and No CCC groupwere as in SRS: (21.23±9.68) vs (28.56±8.76), TPD: (30.03±13.69) %vs (40.37±12.50) %, viable myocardium: (21.77±13.12) % vs (13.66±9.23) %, non-viable myocardium (8.28±8.58) %vs (27.40±12.97) %, all P<0.05; in LVEDV: (109.82±30.01) ml vs (173.71±57.69) ml, LVESV: (62.82±22.39) ml vs (122.53±51.66) ml, LVEF: (43.85±8.46) % vs (31.03±8.30) %, all P<0.05. Conclusion: Our preliminary study found that CCC could maintain left ventricular rest perfusion, myocardial viability and protect cardiac function in patients with chronic total LAD occlusion.

Objective To investigate the relationship between myocardial injury and damage of me-chanical synchrony in the left ventricle of patients with ischemic cardiomyopathy ( ICM) using 99 Tcm-MIBI MPI and gated 18 F-FDG myocardial metabolic PET imaging. Methods A total of 113 ICM patients ( 100 males, 13 females;average age (58±10) years) underwent 99Tcm-MIBI MPI and gated 18F-FDG myocardial metabolic PET imaging from July 2015 to December 2015 in Fu Wai Hospital were retrospectively analyzed. Three-point scoring system was used for quantitative assessment of myocardial ischemia and myocardial in-farction in each segment. Total ischemic score ( TIS) and total scar score ( TSS) of 17 segments were calcu-lated in each patient. The phase bandwidth ( BW) and phase SD were derived from phase analysis. Pearson correlation analysis and logistic regression analysis were used. Results TSS were correlated with BW and SD in all 93 patients with myocardial infarction ( r values:0. 517, 0.470, both P<0.01) and also in a sub-group of 34 patients with myocardial infarction and without myocardial ischemia ( r values: 0. 647, 0. 578, both P<0.01) . There were significant correlations between TIS and BW, SD in 79 patients with myocardial is-chemia ( r values:0.392, 0.378, both P<0.01) , but no significant correlation was found in a subgroup of 20 patients with myocardial ischemia and without myocardial infarction ( r values: 0. 002, -0. 003, both P>0. 05) . Logistic regression analysis showed that the number of myocardial infarction segments and TSS were as-sociated with mechanical dyssynchrony. Conclusion Myocardial infarction is the main factor of left ventricu-lar mechanical dyssynchrony in ICM patients, but chronic myocardial ischemia has no significant influence on mechanical dyssynchrony.

Objective To derive reference limits of cardiac functional parameters (CFP) determined by gated myocardial SPECT imaging, and to analyze the influence of gender, age and weight on CFP. Methods One hundred and seventy-five consecutive outpatients (89 males with age of (48.3±10.7) years and 86 females with age of (49.8±10.4) years) were defined as patients with low-likelihood coronary heart disease (LCHD). All patients underwent adenosine or exercise stress 99Tcm-MIBI G-MPI from February 2008 to April 2011. The EF, EDV and ESV of the left ventricle were measured by quantitative gated SPECT (QGS) software. The reference limits were derived by means of Gaussian distribution or percentiles. The influence of gender, age and weight on CFP was analyzed by multiple regressions for linear models. Two-sample t test was used to analyze data of 2 groups. Parameters between different age groups were compared by one-way analysis of variance. Results The lower reference limit of EF for males was 50%, the upper limit of EDV and ESV was 112 ml and 49 ml respectively. For females, the corresponding reference limits were 54%, 77 ml and 30 ml. Men had higher EDV, ESV (EDV: (75.8±18.3) ml vs (53.3±11.7) ml, t=9.35, P<001; ESV: (27.1±10.9) ml vs (14.3±7.9) ml, t=8.59, P<0.01) and lower EF than women ((65.1±76)% vs (74.7±10.0)%, t=-6.92, P<0.01). The incidence of small hearts in women was 76%(65/86). The gender and age was the primary and secondary predictors of both of EF and ESV, while the body weight was a significantly third predictor for cardiac volume. Patients were dived into different age (≤40 years, 41-49 years, ≥50 years) groups. For males, EDV, ESV and EF were not significantly different among the different age groups (F values: 1.106, 0.954, 1.029, all P>0.05). For females, EDV was not different (F=2408, P>005), while ESV and EF were significantly different among 3 groups (F values: 5.010, 6.229, both P<0.05). Conclusions The CFP determined by G-MPI in LCHD patients are significantly affected by gender and age. The age-related changes of CFP in males are different from those in females.