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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.

Purpose: The noninvasive imaging of bacterial infections is critical in order to reduce mortality and morbidity caused by these diseases. The recently reported (18)F-FDS ((18)F-2-fluorodeoxy sorbitol) as a PET (positron emission tomography) tracer can be used to image Enterobacteriaceae-specific infections and provides a potential alternative to this problem compared with other probes for imaging infections. In this study, automatic synthesis, validation of (18)F-FDS and a first-in-human study were performed and discussed., Methods: A multifunctional synthesis module was employed for the radiosynthesis of (18)F-FDG ((18)F-2-fluorodeoxy glucose) and (18)F-FDS starting from (18)F ion using two-pot three-step fully automated reactions. The behavior of (18)F-FDS as an in vivo imaging probe for infections was evaluated in an Escherichia coli mouse infection model. The first detailed pharmacokinetic and biodistribution parameters were obtained from healthy human volunteers., Results: The uptake of (18)F-FDS in an E. coli mouse-myositis infection model was easily differentiated from other organs and normal muscle. Intensive lesion uptake declined after antibiotic treatment. In the pilot human study, no adverse effects due to (18)F-FDS were observed up to 24 h post-injection. The radiotracer was rapidly cleared from the circulation and excreted mainly through the urinary system., Conclusion: We conclude that (18)F-FDS PET holds great potential for appropriate and effective for the imaging of bacterial infections in vivo. These preliminary results indicate that further clinical studies are warranted., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Objectives: Tumor-induced osteomalacia (TIO) is generally caused by small benign mesenchymal tumors producing fibroblast growth factor-23 (FGF-23). The only curative therapy of the disease is resection of the causative tumors. However, these tumors are extremely difficult to detect using conventional imaging modalities. This research was undertaken to evaluate efficacy of (68)Ga DOTATATE PET/CT in this clinical setting., Methods: Images of (68)Ga DOTATATE PET/CT and clinical charts from 54 patients with clinically suspected TIO were retrospectively reviewed. The image findings were compared with the results of histopathological examinations and clinical follow-ups., Results: (68)Ga DOTATATE PET/CT scans were positive in 44 patients, among which, 33 had surgery to remove the lesions. Postsurgical pathological examination confirmed causative tumors in 32 patients whose symptoms diminished promptly, and the serum phosphate levels became normal, which confirmed the diagnoses of TIO. Eleven patients with positive (68)Ga DOTATATE PET/CT did not have surgery. These 11 patients continued to have symptoms and hypophosphatemia but were not included in the final analysis because of lack of evidence to confirm or exclude TIO. Ten patients had negative (68)Ga DOTATATE PET/CT scans. All of these10 patients responded to conservative therapy and had normal serum phosphate levels in the follow-up, which excluded TIO. Therefore, the (68)Ga DOTATATE PET/CT imaging had a sensitivity of 100% (32/32) and a specificity of 90.9% (10/11). The overall accuracy of (68)Ga DOTATATE PET/CT scan in the detection of tumors responsible for osteomalacia is 97.7% (42/43)., Conclusions: (68)Ga DOTATATE PET/CT scan is an accurate imaging modality in the detection of tumors causing TIO.

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.

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.

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 × 10(-4)), norepinephrine (P = .002), or both (P = 2.19 × 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.

This study was designed to investigate the distribution of the independent parameters of PET and MR in tumour differentiation and staging and to evaluate the diagnostic efficiency of the independent parameters and combined model of PET/MR in the tumour differentiation of head and neck squamous cell carcinoma (HNSCC). The patients with the preliminary diagnosis of HNSCC were included and underwent the integrated PET/MR The parameters included the diffusion-weighted imaging, dynamic contrast enhancement and PET. The correlations between different parameters and the distribution in groups of tumour differentiation and staging were analysed. The combined model was established with complementary PET/MR parameters. The diagnostic efficiency of the independent parameters and combined model in the tumour differentiation were analysed by receiver operating characteristic curve. The correlations between the parameters of dynamic contrast enhancement and PET were most significant. There were significant differences between the well-differentiated group and the moderately/poorly differentiated group in terms of the mean values of apparent diffusion coefficient (ADC) and standardised uptake value (SUV) (p < 0.05). The distributions among different tumour stage groups were not statistically different in all the parameters. The diagnostic efficiency of tumour differentiation increased in the order of Kepmean, SUVmean, ADCmean, and the combined model. Compared with the independent parameter, the combination of multiple parameters with PET/MR can further improve the diagnostic performance of tumour differentiation in HNSCC. [ABSTRACT FROM AUTHOR]