Objective:To investigate whether the image quality of total-body PET/CT (TB PET/CT) with 1 min acquisition can meet the clinical diagnostic requirements.Methods:From May 2019 to September 2021, a total of 90 malignant tumor patients (60 males, 30 females, age 31-86 years) with primary lesions confirmed by pathological diagnosis in Zhongshan Hospital, Fudan University were respectively analyzed. All patients underwent conventional PET/CT (C PET/CT) scan with conventional clinical acquisition and TB PET/CT scan with 1 min acquisition after injecting 18F-FDG in random order. Paired t test or Wilcoxon signed rank test was used to analyze the image quality of these two scans. Results:SUV max of primary lesions in TB PET/CT group was significantly higher than that in C PET/CT group (15.9(7.9, 24.6) vs 12.5(5.8, 16.6); z=8.14, P<0.001), so were signal-to-noise ratio (SNR) of the blood pool, liver, muscles (9.3±3.0, 11.4(9.5, 14.2), 8.3(7.3, 10.1) vs 6.2±1.7, 9.4(7.7, 11.8), 6.0(4.9, 7.1)), tumor-to-blood pool ratio (TBR) (9.3(4.3, 14.8) vs 8.5(4.3, 11.1)), tumor-to-liver ratio (TLR) (6.7(3.0, 10.4) vs 6.1(2.9, 7.7)), tumor-to-muscle ratio (TMR) (23.2(11.5, 38.0) vs 18.3(9.6, 26.6); t=9.36, z values: 4.44-7.40, all P<0.001). Conclusion:The image quality of TB PET/CT scan with 1 min acquisition can meet the diagnostic requirements, and is better than the C PET/CT image quality with conventional clinical acquisition.

Liver cancer has high morbidity and mortality worldwide.Traditional morphological imaging can offer crucial anatomical information for the diagnosis and treatment of liver cancer,and when combined with the functional data shown by PET imaging,the diagnostic accuracy of tumors can be further improved and assisted in treatment selection.Fibroblast activation protein(FAP),a signature protein of cancer-associated fibroblasts,is highly expressed in a variety of malignant tumors of epithelial origin and is an important target for tumor diagnosis and treatment.Compared with routinely applied 18F-fluorodeoxyglucose(FDG)PET imaging,FAP inhibitor(FAPI)PET imaging has the advantages of high image contrast and independence from blood glucose.In recent years,a variety of radiopharmaceuticals targeting FAP have been continuously expanded in the diagnosis,staging and targeted therapy of different liver cancer types,and the progress of their related applications is reviewed in this paper.

177Lu-prostate specific membrane antigen(PSMA)radio-ligand therapy has been approved abroad for advanced prostate cancer and has been in several clinical trials in China.Based on domestic clinical practice and experimental data and referred to international experience and viewpoints,the expert group forms a consensus on the clinical application of 177Lu-PSMA radio-ligand therapy in prostate cancer to guide clinical practice.

68Ga-DOTATATE/18F-FDG two-day low-dose total-body PET/CT imaging is increasingly employed to facilitate the diagnosis,prognosis,and heterogeneity assessment of neuroendocrine neoplasms.We present a consensus on operational guideline for a two-day combined imaging from experts in low-dose/ultra-low-dose total-body PET/CT from several domestic medical institutions.

Objective:To explore whether the specific synaptic vesicle glycoprotein 2A (SV2A) targeted imaging agent ( R)-4-(3-fluoro-5-(fluoro- 18F)phenyl)-1-((3-methylpyridin-4-yl)methyl)pyrrolidin-2-one ( 18F-SDM-8) can be used to detect epileptic foci. Methods:Twenty male Sprague-Dawley (SD) rats (8-9 weeks) were injected with 1.2 μl of kainic acid (16 rats in the epilepsy group) or saline (4 rats in the control group) into the right hippocampus. 18F-SDM-8 and 18F-FDG mircoPET/CT imaging were respectively performed at 1-2 d (acute phase), 6-7 d (incubation period) and 45-60 d (chronic phase) after the seizure. Asymmetric index (AI) was used to evaluate the epileptic foci identify ability of 18F-SDM-8. Paired t test, Mann-Whitney U test and Pearson correlation analysis were used to analyze data. Results:In the three periods of 18F-SDM-8 imaging, the differences of AI of hippocampus between the epilepsy group and control group were statistically significant ( z values: from -2.64 to 2.67, all P<0.05). Both imaging agents had asymmetric uptake in the epilepsy group (right was lower than left), and the decrease in the medial right temporal lobe was the most significant. The pathological staining results were consistent with the imaging results. In the chronic phase of the epilepsy group, the differences of 18F-SDM-8 SUV mean (right versus left) in each brain area of interest were statistically significant ( t value: from -33.40 to -5.60, all P<0.05). The asymmetric uptake of the two imaging agents in the hippocampus had a better correlation ( r=0.97, P=0.001), and the AI of 18F-SDM-8 ((34.2±8.4)%) in this area was 1.4 times higher than that of 18F-FDG ((24.6±4.7)%). Conclusions:18F-SDM-8 PET is a promising method to test the level of SV2A. It can reflect the changes of SV2A in the rat epilepsy model induced by intrahippocampal injection of kainic acid, and improve the sensitivity of molecular imaging for epileptic foci.

Objective:To investigate the value of 68Ga-1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetraacetic acid- D-Phe1-Tyr3-Thr8-octreotide (DOTATATE) combined with 18F-FDG total-body PET/CT imaging in the diagnosis and heterogeneity assessment of primary foci of neuroendocrine neoplasms (NEN). Methods:Clinical, imaging and pathological data of 39 patients with pathological diagnosis (30 NEN and 9 non-NEN, 18 males and 21 females, age (54.0±11.4) years) who underwent 1/10 activity 18F-FDG and 1/2 activity 68Ga-DOTATATE total-body PET/CT combined imaging in Zhongshan Hospital, Fudan University from August 2020 to March 2023 were retrospectively analyzed. The NEN primary foci were classified as neuroendocrine tumor (NET) G1, G2, G3, and neuroendocrine carcinoma (NEC). Diagnostic efficacy of combined dual-low activity dual-tracer imaging for NEN primary foci and its value for evaluating tumor heterogeneity were analyzed. Results:The sensitivities, specificities, and accuracies of 68Ga-DOTATATE alone and in combination with 18F-FDG total-body PET/CT for the diagnosis of NEN primary foci were 81.2%(26/32), 7/9, 80.5%(33/41) and 90.6%(29/32), 7/9, 87.8%(36/41), respectively. Ten NET G1 and seven NET G2 lesions showed 68Ga-DOTATATE uptake and no 18F-FDG uptake; two NET G2 lesions showed no 68Ga-DOTATATE uptake but 18F-FDG uptake; and two NET G1 and six NET G2 lesions showed both 68Ga-DOTATATE and 18F-FDG uptake. The radiation doses of 68Ga-DOTATATE, 18F-FDG and a single examination of CT were (1.59±0.50), 0.49(0.44, 0.58) and 11.46(10.53, 12.85) mSv, respectively. Conclusion:Combining total-body PET/CT imaging with dual tracers can effectively diagnose NEN primary foci and assess inter-tumor heterogeneity.

Objective:To explore the feasibility of one-tenth dose 18F-FDG total-body PET/CT (TB PET/CT) in patients with malignant tumors. Methods:A retrospective analysis was carried out on 34 preliminarily diagnosed cancer patients (30 males, 4 females, age (64.0±1.6) years) who underwent one-tenth dose (0.37 MBq/kg) 18F-FDG TB PET/CT examination between April 2020 and September 2022 in Zhongshan Hospital, Fudan University. The raw data were reconstructed into 15 min and initial 2 min PET images (G15 and G2, respectively). A matched cohort of 34 preliminarily diagnosed malignant tumor patients (27 males, 7 females, age (63.3±2.1) years) undergoing full dose (3.70 MBq/kg) 18F-FDG conventional digital PET/CT (C PET/CT) examination with a PET scan rate of 2-3 min/bed position, were analyzed in line with the same pathological types. Signal-to-noise ratios (SNR) of G15, G2 and C PET/CT groups were compared, and based on the pathological results, the detection rates of those 3 groups for lesions were also compared. The χ2 test, independent sample t-test, Mann-Whitney U test, and Wilcoxon rank sum test were used for data analysis. Results:The significant differences in gender, age, body mass index (BMI), blood sugar level and postinjection waiting time between TB PET/CT group and C PET/CT group were not found ( χ2=0.98, t values: 0.08, -1.05, z values: 0.68, 0.41, all P>0.05). The SNR, from G15 to C PET and G2 groups, decreased gradually, which were 16.0(11.3, 20.0), 10.5(8.2, 13.5) and 8.4±0.3 respectively ( z values: 5.09, 3.31, -4.24, all P<0.05). All primary lesions and hepatic metastases were detected by G15 and G2 imaging (100%, 37/37) as well as by C PET/CT (100%, 36/36). The detection rates for lymph node metastasis lesions were 10/15 in the G2/G15 groups, which were higher than the detection rate in the C PET/CT group (64.4%(29/45); χ2=62.03, P=0.002). Conclusion:One-tenth dose 18F-FDG TB PET/CT with a 2-minute acquisition is feasibility in the clinical practice.

Comparing to the conventional PET/CT, the advantage of total-body PET/CT lies in the long axial field-of-view (LAFOV) which improves the system sensitivity by 40 times, allowing rapid scan, low-dosing imaging and total-body dynamic imaging. Total-body PET/CT can increase the throughput of patients, reduce the radiation dose, and observe the drug metabolism in vivo both real-time and dynamically. Its high sensitivity makes long-time delay scan possible in clinic research. Besides, it also has potential advantages in drugs development and in the field of pharmacokinetic researches.

Objective:To investigate the value of total-body PET/CT 2 h imaging with half-dose 18F-FDG in the detection of active lesions of Takayasu arteritis (TA). Methods:Fifty-five patients with TA(13 males, 42 females, age: (34.3±13.9) years), who accepted 2 h total-body 18F-FDG PET/CT scan with half-dose activity in Zhongshan Hospital, Fudan University between January 2020 and June 2021, were retrospectively enrolled. TA was diagnosed according to the American College of Rheumatology (ACR) criteria. Patients were categorized into active TA group and inactive TA group based on the National Institutes of Health (NIH) criteria. Lesions with SUV max≥(liver SUV max- 0.1) were defined as active lesions. If multiple lesions occurred in one artery segment, only the lesion with the highest SUV max was chosen. Lesion-to-blood SUV max ratio was calculated. The independent-sample t test or Mann-Whitney U test was used to analyze the liver SUV max, blood pool SUV max and lesion-to-blood ratio between those 2 groups. Results:A total of 363 active lesions were found in 39 patients with active TA and 137 lesions were found in 16 patients with inactive TA. The liver SUV max (1.93±0.45 vs 1.95±0.35; t=0.20, P=0.846) and blood pool SUV max (0.75(0.63, 0.98) vs 0.90(0.77, 1.01); z=-1.45, P=0.148) of patients with active and those with inactive TA were not significantly different. The lesion-to-blood ratio in active TA group was higher than that in inactive TA group (3.09(2.36, 4.24) vs 2.57(2.24, 3.25); z=4.05, P<0.001). Conclusions:Total-body PET/CT 2 h imaging has qualified lesion-to-blood ratio in TA imaging. Inflammatory lesions of vascular wall can be detected sensitively in both patients with active TA and those with inactive TA.

Objective:To explore the effect of dietary intake before fasting on the physiological distribution of 18F-FDG PET/CT, and to improve the 18F-FDG PET/CT image quality. Methods:From August 2019 to May 2020, questionnaire of dietary intake before fasting of 118 patients (73 males, 45 females; age (58.4±13.4) years) who performed PET/CT imaging in Zhongshan Hospital, Fudan University were retrospectively analyzed. The total dietary energy intake, the nutrient intake and energy supply ratio of the three energy source nutrients, the type of raw materials and the texture of diet were included. The SUV max and SUV mean of the liver, mediastinal blood pool and hip muscles were measured. Single-factor and multi-factors linear regression analyses were used to analyze data. Results:The fasting blood glucose of 118 subjects was (5.36±1.01) mmol/L. The texture of diet before fasting were general diet, semiliquid diet and liquid diet, which were 42 (35.59%), 72 (61.02%) and 4 (3.39%) subjects, respectively. The energy supply ratios of carbohydrate, protein and fat were (55.46±18.27)%, (16.70±7.38)% and (27.72±14.53)%, respectively. The results of multi-factors regression analysis indicted that protein energy ratio was an independent factor influencing SUV max ( β=0.005, P=0.031) and SUV mean ( β=0.003, P=0.042) of the hip muscles, and the texture of diet was an independent factor influencing SUV max ( β=0.126, P=0.030) and SUV mean ( β=0.197, P=0.002) of mediastinal blood pool. Conclusions:The dietary intake before fasting has significant effect on the imaging quality of 18F-FDG. The protein energy ratio is an independent factor influencing SUV max and SUV mean of the hip muscles. The texture of diet is an independent factor influencing SUV max and SUV mean of mediastinal blood pool.