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Gliomas are the most common primary intracranial tumors in adults, among which high-grade glioma patients are characterized by short survival and poor prognosis. The diagnosis, treatment, evaluation of effective treatments, and prognosis prediction of high-grade gliomas are of great significance for improving patient survival. Conventional enhanced magnetic resonance imaging has deficiencies in delineating tumor extent, identifying tumor progression and treatment-related changes. Therefore, there is a broad consensus to incorporate amino acid PET, and 18F-FET PET inparticular, into the diagnostic and therapeutic process of high-grade gliomas. In this article, we review the new research progress of 18F-FET PET in the diagnosis and treatment of adult high-grade glioma in recent years.

Purpose: Dynamic PET/CT scan of 68Ga-FAPI-04 in patients with suspected malignant hepatic lesions were retrospectively analyzed to find the optimal acquisition time with better lesion detection rate. Methods: Twenty-two patients with lesions confirmed by CT or MRI were performed with dynamic 68Ga-FAPI-04 PET/CT scan. Tracer uptake of lesions and normal organs at different time points were analyzed. Standardized uptake value (SUV) and tumor-to-background (TBR) were calculated based on the quantification of images. Results: SUV of normal organs decreased rapidly from 10 to 30 min and decreased gradually from 30 to 60 min. Besides, the uterus showed a particularly high uptake in all patients (12.62 ± 4.58 at 10 min p.i., 12.04 ± 3.99 at 30 min p.i., 10.92 ± 2.38 at 60 min p.i.). SUV of lesions decreased gradually, while TBR increased from 10- to 60-min post-injection. Visual analysis verified a comparable lesion detectability of 30 min and 60 min with images of 10 min showing a decreased lesion detection number. Conclusion: This study revealed that similar detection rates were achieved at both 30 and 60 min, suggesting a static scan at 30 min to be appropriate in the clinic. Besides, although with high lesion uptake, early 68Ga-FAPI-04 PET imaging at 10 min after tracer injection could cause missed lesion detection. [ABSTRACT FROM AUTHOR]

Purpose: To determine the optimal imaging tool for clinical evaluation of pancreatic neoplasm by comparing the performance of 18F-FDG PET/MRI and PET/CT.Procedures: Patients with suspected pancreatic neoplasms underwent PET/MRI and PET/CT in the same day prior to resection or endoscopic ultrasound-guided fine-needle aspiration. Histology served as the golden standard of lesion classification. Visual assessment on lesion type and lesion malignancy via PET/MRI and PET/CT images was compared. Standard uptake values (SUVs) of PET images from the two scanners were measured and their correlations were further evaluated.Results: Thirty-nine patients were included for the final analysis. In visual assessment, we found MRI achieved better performance than CT in differentiating solid and cystic neoplasms, with accuracy of 100% vs. 87%, respectively. In visual malignancy diagnosis, the accuracy of PET/CT was 92.3% for overall lesions and 90.9% for cysts, while the accuracy of PET/MRI was 92.3% and 86.4%, respectively. Besides, semi-quantitative analysis achieved better specificity than visual assessment for both hybrid modalities (100% vs. 87.5% for PET/CT; 100% vs. 81.5% for PET/MR). Furthermore, strong correlation of SUV was found between PET/CT and PET/MRI, with Pearson's correlation coefficients > 0.82.Conclusions: In this study, we found PET/MRI and PET/CT, both using 18F-FDG as tracer, had comparable overall performance in identification of pancreatic neoplasms. Interestingly, for patients who had suspected pancreatic neoplasm but invisible FDG uptake, PET/MRI had shown exceptionally better performance, probably because MR images could detect tiny abnormal structures to improve diagnosis. [ABSTRACT FROM AUTHOR]

Introduction: The purpose of this study was to evaluate subjects with high-risk alcohol cardiotoxicity and patients with alcoholic cardiomyopathy (ACM) via dynamic 11C-Acetate positron emission tomography (PET) imaging as a myocardial oxidative metabolic probe. Methods and Results: We recruited 37 subjects with chronic alcohol consumption [18 with moderate consumption (MC), 19 with heavy consumption (HC)], 5 ACM patients, and 12 healthy controls to receive dynamic 11C-Acetate PET scans. PET imaging data were analyzed to calculate kinetic parameters (e.g., Kmono, K1 and k2) based on the mono-exponential and one-tissue compartmental models. Myocardial oxygen consumption (MVO2) and myocardial external efficiency (MEE) were then derived from these kinetic parameters. MVO2 was significantly lowered in the HC group and in ACM patients (0.121± 0.018 and 0.111 ± 0.017 mL·g−1·min−1, respectively) compared with those in healthy controls and MC subjects (0.144 ± 0.023 and 0.146 ± 0.027 mL·g−1·min−1, respectively; P <.01). MEE was significantly reduced in ACM patients (13.0% ± 4.3%) compared with those of healthy controls (22.4% ± 4.6%, P <.01), MC subjects (20.1% ± 4.5%, P <.05), and HC subjects (22.3% ± 4.5%, P <.001). Conclusion: Functional assessment via dynamic 11C-Acetate PET imaging may represent a clinically feasible probe for identifying cohorts with high-risk cardiotoxicity due to addictive alcohol consumption and ACM. [ABSTRACT FROM AUTHOR]

Brown adipose tissue (BAT) is emerging as a potential target for treating human obesity. It has been indicated that BAT is rich in innervations of sympathetic nerve control. Using [sup.18]F-FDG microPET imaging, this study aims at evaluating how factors related to sympathetic activation/inhibition changed BAT metabolism of mice. BAT [sup.18]F-FDG uptake were semiquantitatively evaluated in different groups of mice under temperature (cold or warm stimulus) or pharmacological interventions (norepinephrine, epinephrine, isoprenaline, or propranolol) and were compared with the corresponding controls. It was found that BAT activation can be stimulated by cold exposure (P = 1.96 x [10.sup.-4]), norepinephrine (P = .002), or both (P = 2.19 x [10.sup.- 6]) within an hour before [sup.18]F-FDG injection and can also be alleviated by warming up (P = .001) or propranolol lavage (P = .027). This preliminary study indicated that BAT function could be evaluated by [sup.18]F-FDG PET imaging through short-term interventions, which paved the way for further investigation of the relationship between human obesity and BAT dysfunction., 1. Introduction Brown adipose tissue (BAT) is a kind of fat tissue different from white adipose tissue (WAT). In mammals, BAT has its function mainly in nonshivering thermogenesis, responsible for [...]

Objective: Previously we observed that dual phase 11C-acetate positron emission tomography (AC-PET) could be employed for differential diagnosis of liver malignancies. In this study, we prospectively evaluated the effect of dual phase AC-PET on differential diagnosis of primary hepatic lesions of 1–3 cm in size. Methods: 33 patients having primary hepatic lesions with size of 1–3 cm in diameter undertook dual phase AC-PET scans. Procedure included an early upper-abdomen scan immediately after tracer injection and a conventional scan in 11–18 min. The standardized uptake value (SUV) was calculated for tumor (SUVT) and normal tissue (SUVB), from which 11C-acetate uptake ratio (as lesion against normal liver tissue, SUVT/SUVB) in early imaging (R1), conventional imaging (R2), and variance between R2 and R1 (ΔR) were derived. Diagnoses based on AC-PET data and histology were compared. Statistical analysis was performed with SPSS 19.0. Results: 20 patients were found to have HCC and 13 patients had benign tumors. Using ΔR>0 as criterion for malignancy, the accuracy and specificity were significantly increased comparing with conventional method. The area under ROC curve (AUC) for R1, R2, and ΔR were 0.417, 0.683 and 0.831 respectively. Differential diagnosis between well-differentiated HCCs and benign lesions of FNHs and hemangiomas achieved 100% correct. Strong positive correlation was also found between R1 and R2 in HCC (r2 = 0.55, P<0.001). Conclusions: Dual phase AC-PET scan is a useful procedure for differential diagnosis of well-differentiated hepatocellular carcinoma and benign lesions. The dynamic changes of 11C-acetate uptake in dual phase imaging provided key information for final diagnosis. [ABSTRACT FROM AUTHOR]

Brown adipose tissue (BAT) is emerging as a potential target for treating human obesity. It has been indicated that BAT is rich in innervations of sympathetic nerve control. Using (18)F-FDG microPET imaging, this study aims at evaluating how factors related to sympathetic activation/inhibition changed BAT metabolism of mice. BAT (18)F-FDG uptake were semiquantitatively evaluated in different groups of mice under temperature (cold or warm stimulus) or pharmacological interventions (norepinephrine, epinephrine, isoprenaline, or propranolol) and were compared with the corresponding controls. It was found that BAT activation can be stimulated by cold exposure (P = 1.96 x 10(-4)), norepinephrine (P = .002), or both (P = 2.19 x 10(-6)) within an hour before (18)F-FDG injection and can also be alleviated by warming up (P = .001) or propranolol lavage (P = .027). This preliminary study indicated that BAT function could be evaluated by (18)F-FDG PET imaging through short-term interventions, which paved the way for further investigation of the relationship between human obesity and BAT dysfunction. [ABSTRACT FROM AUTHOR]

Fibroblast activation protein contributes to immunosuppression and resistance to immunotherapies. This study aimed to compare baseline 68 Ga-labeled fibroblast activation protein inhibitor ( 68 Ga-FAPI) PET/CT and 18 F-FDG PET/CT in response and survival prediction in unresectable hepatocellular carcinoma (uHCC) patients treated with the combination of programmed cell death 1 (PD-1) inhibitor and lenvatinib. Methods: In this prospective cohort study, 22 patients with uHCC who underwent baseline 18 F-FDG and 68 Ga-FAPI PET/CT and soon began taking a combination of PD-1 inhibitor and lenvatinib were recruited. Semiquantitative indices of baseline PET/CT were measured as 18 F-FDG SUV max , metabolic tumor volume, total lesion glycolysis, 68 Ga-FAPI SUV max , 68 Ga-FAPI-avid tumor volume (FTV), and total lesion fibroblast activation protein expression (TLF). The primary endpoint was durable or nondurable clinical benefit after treatment, and the secondary endpoints were progression-free survival (PFS) and overall survival (OS). Results: The overall response rate of the combination therapy was 41% (9/22). Fifty percent of patients had durable clinical benefit. Median PFS and OS were 4.8 and 14.4 mo, respectively. Patients with nondurable clinical benefit showed a significantly higher FTV and TLF than those with durable clinical benefit, whereas 18 F-FDG parameters overlapped. A higher 68 Ga-FAPI-avid tumor burden (FTV > 230.46 cm 3 or TLF > 961.74 SUV body weight ⋅cm 3 ) predicted both shorter PFS (4.0 vs. 13.5 mo, P = 0.016) and shorter OS (7.8 mo vs. not reached, P = 0.030). Patients with a higher metabolic tumor burden (metabolic tumor volume > 206.80 cm 3 or total lesion glycolysis > 693.53 SUV body weight ⋅cm 3 ) showed a shorter OS although the difference did not reach statistical significance ( P = 0.085). In multivariate analysis, a higher 68 Ga-FAPI-avid tumor burden (hazard ratio [HR], 3.88 [95% CI, 1.26-12.01]; P = 0.020) and macrovascular invasion (HR, 4.00 [95% CI, 1.06-15.14]; P = 0.039) independently predicted a shorter PFS, whereas a higher 68 Ga-FAPI-avid tumor burden (HR, 5.92 [95% CI, 1.19-29.42]; P = 0.035) and bone metastases (HR, 5.88 [95% CI, 1.33-25.93]; P = 0.022) independently predicted a shorter OS. Conclusion: Volumetric indices on baseline 68 Ga-FAPI PET/CT were potentially independent prognostic factors to predict durable clinical benefit, PFS, and OS in uHCC patients treated with a combination of PD-1 and lenvatinib. Baseline 68 Ga-FAPI PET/CT may facilitate uHCC patient selection before combination therapy., (© 2023 by the Society of Nuclear Medicine and Molecular Imaging.)

Introduction: The attenuation correction technique of single photon emission computed tomography (SPECT) images is essential for early diagnosis, therapeutic evaluation, and pharmacokinetic studies of lung cancer. 99m Tc-3PRGD 2 is a novel radiotracer for the early diagnosis and evaluation of treatment effects of lung cancer. This study preliminary discusses the deep learning method to directly correct the attenuation of 99m Tc-3PRGD 2 chest SPECT images., Methods: Retrospective analysis was performed on 53 patients with pathological diagnosis of lung cancer who received 99m Tc-3PRGD 2 chest SPECT/CT. All patients' SPECT/CT images were reconstructed with CT attenuation correction (CT-AC) and without attenuation correction (NAC). The CT-AC image was used as the reference standard (Ground Truth) to train the attenuation correction (DL-AC) SPECT image model using deep learning. A total of 48 of 53 cases were divided randomly into the training set, the remaining 5 were divided into the testing set. Using 3D Unet neural network, the mean square error loss function (MSELoss) of 0.0001 was selected. A testing set is used to evaluate the model quality, using the SPECT image quality evaluation and quantitative analysis of lung lesions tumor-to-background (T/B)., Results: SPECT imaging quality metrics between DL-AC and CT-AC including mean absolute error (MAE), mean-square error (MSE), peak signal-to-noise ratio (PSNR), structural similarity (SSIM), normalized root mean square error (NRMSE), and normalized Mutual Information (NMI) of the testing set are 2.62 ± 0.45, 58.5 ± 14.85, 45.67 ± 2.80, 0.82 ± 0.02, 0.07 ± 0.04, and 1.58 ± 0.06, respectively. These results indicate PSNR > 42, SSIM > 0.8, and NRMSE < 0.11. Lung lesions T/B (maximum) of CT-AC and DL-AC groups are 4.36 ± 3.52 and 4.33 ± 3.09, respectively (p = 0.81). There are no significant differences between two attenuation correction methods., Conclusion: Our preliminary research results indicate that using the DL-AC method to directly correct 99m Tc-3PRGD 2 chest SPECT images is highly accurate and feasible for SPECT without configuration with CT or treatment effect evaluation using multiple SPECT/CT scans., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The reviewer GH declared a shared affiliation with the authors to the handling editor at the time of review., (Copyright © 2023 Xing, Wang, Jin, Tian, Ba, Jing and Li.)

Increased expression of fibroblast-activating protein (FAP) in fibrous caps may contribute to progression of atherosclerotic plaques. Methods: Forty-one patients who underwent 68 Ga-conjugated quinoline-based FAP inhibitor ( 68 Ga-FAPI-04) PET/CT for noncardiovascular indications were retrospectively analyzed. Correlations were assessed between the uptake of 68 Ga-FAPI-04 in large arterial walls (SUV max and target-to-background ratio, TBR) and degree of calcification and cardiovascular risk factors. Results: Focal arterial uptake of 68 Ga-FAPI-04 or calcification was detected in 1,177 arterial segments in all 41 patients. TBR was negatively correlated with the degree of calcification (Hounsfield units) ( r = -0.27, P < 0.01). Mean TBR in higher-risk patients was greater than in lower-risk patients (2.2 ± 0.3 vs. 1.8 ± 0.3, P < 0.01). Immunohistochemical labeling of carotid plaques exhibited prominent FAP expression in a thin fibrous cap and moderate FAP expression in a thick cap. Conclusion: 68 Ga-FAPI-04 PET/CT might have potential for imaging fibroblastic activation in the arterial wall., (© 2022 by the Society of Nuclear Medicine and Molecular Imaging.)

Brown adipose tissue (BAT) is important in monitoring energy homeostasis and cancer cachexia. Different from white adipose tissue, BAT is characterized by the presence of a large number of mitochondria in adipocytes. Translocator protein 18 kDa (TSPO), a critical transporter, is expressed in the outer membrane of mitochondria. We speculated that [ 18 F]DPA714, a specific TSPO tracer, may monitor BAT activity in tumor-bearing mice in vivo. We first analyzed the radioactive uptake of positron emission tomography (PET) tracers in BAT of CT26 xenograft mice with 18F-fluorodeoxyglucose ([ 18 F]FDG) and [ 18 F]DPA714. We also studied the BAT uptake of [ 18 F]DPA714 in CT26, A549 and LLC tumor models. The dynamic distribution of [ 18 F]FDG is quite variable among animals, even in mice of the same tumor model (%ID/g-mean: mean ± SDM, 8.61 ± 8.90, n = 16). Contrarily, [ 18 F]DPA714 produced high-quality and stable BAT imaging in different tumor models and different animals of the same model. Interestingly, %ID/g-mean of [ 18 F]DPA714 in BAT was significantly higher on day 26 than that on day 7 in CT26 xenograft model. Taken together, these results strongly indicate the potential feasibility of [ 18 F]DPA714 PET imaging in investigating BAT and energy metabolism during tumor progression in preclinical and clinical study.

Objective: To compare and analyze the positron emission tomography (PET) images with other multi-modalities in the diagnosis of hepatic tumors., Methods: A total of 158 patients undergoing (18)F fluorodeoxyglucose (FDG)-PET were enrolled along with another 55 cases with (11)C acetate-PET (AC-PET) imaging within 1 week. The pathological results were taken as the golden criteria. Tumor marker, contrast ultrasound, computed tomography (CT) and magnetic resonance imaging (MRI) results were collected.SPSS 19.0 was used for statistical analysis., Results: Contrast MRI, ultrasound and CT were more effective than PET in the differential diagnosis of hepatic tumor.FDG-PET showed a better accuracy in the diagnosis of intrahepatic cholangiocarcinomas, metastasis and rare primary hepatic carcinoma. AC-PET was a good complementary method to FDG-PET. Consideration of tumor size, amount, laboratory results and history could improve the diagnostic accuracy of PET and enhanced CT., Conclusion: PET must be combined with other image modalities to differentiate hepatic tumors more effectively and accurately.