Comparison of Baseline 68Ga-FAPI and 18F-FDG PET/CT for Prediction of Response and Clinical Outcome in Patients with Unresectable Hepatocellular Carcinoma Treated with PD-1 Inhibitor and Lenvatinib.

Fibroblast activation protein contributes to immunosuppression and resistance to immunotherapies. This study aimed to compare baseline 68Ga-labeled fibroblast activation protein inhibitor (68Ga-FAPI) PET/CT and 18F-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 18F-FDG and 68Ga-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 18F-FDG SUVmax, metabolic tumor volume, total lesion glycolysis, 68Ga-FAPI SUVmax, 68Ga-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 18F-FDG parameters overlapped. A higher 68Ga-FAPI-avid tumor burden (FTV > 230.46 cm3 or TLF > 961.74 SUVbody weight⋅cm3) 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 cm3 or total lesion glycolysis > 693.53 SUVbody weight⋅cm3) showed a shorter OS although the difference did not reach statistical significance (P = 0.085). In multivariate analysis, a higher 68Ga-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 68Ga-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 68Ga-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 68Ga-FAPI PET/CT may facilitate uHCC patient selection before combination therapy.

Preclinical and pilot clinical evaluation of a small-molecule carbonic anhydrase IX targeting PET tracer in clear cell renal cell carcinoma.

PURPOSE: Clear cell renal cell carcinoma (ccRCC) highly expresses carbonic anhydrase IX (CAIX). The purpose of this study was to evaluate 68Ga-NY104, a small-molecule CAIX-targeting PET agent, in tumor models of ccRCC and patients diagnosed with confirmed, or suspicious, ccRCC. METHODS: The in vivo and ex vivo biodistribution of 68Ga-NY104 was investigated in CAIX-positive OS-RC-2 xenograft-bearing models. The binding of the tracer was further validated using autoradiography for human ccRCC samples. In addition, three patients with confirmed or suspicious ccRCC were studied. RESULTS: NY104 can be labeled with high radiochemical yield and purity. It quickly cleared through kidney with α-half-life of 0.15 h. Discernible uptake is noted in the heart, lung, liver, stomach, and kidney. The OS-RC-2 xenograft demonstrated intense uptake 5 min after injection and gradually increased until 3 h after injection with ID%/g of 29.29 ± 6.82. Significant binding was detected using autoradiography on sections of human ccRCC tumor. In the three patients studied, 68Ga-NY104 was well-tolerated and no adverse events were reported. Substantial accumulation was observed in both primary and metastatic lesions in patient 1 and 2 with SUVmax of 42.3. Uptake in the stomach, pancreas, intestine, and choroid plexus was noted. The lesion in third patient was correctly diagnosed as non-metastatic for negative 68Ga-NY104 uptake. CONCLUSION: 68Ga-NY104 can efficiently and specifically bind to CAIX. Given the pilot nature of our study, future clinical studies are warranted to evaluate 68Ga-NY104 for detection of CAIX-positive lesions in patients with ccRCC. TRIAL REGISTRATION: The clinical evaluation part of this study was retrospectively registered at ClinicalTrial.gov (NCT05728515) as NYPILOT on 6 Feb, 2023.

Direct attenuation correction for 99mTc-3PRGD2 chest SPECT lung cancer images using deep learning.

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. 99mTc-3PRGD2 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 99mTc-3PRGD2 chest SPECT images. Methods: Retrospective analysis was performed on 53 patients with pathological diagnosis of lung cancer who received 99mTc-3PRGD2 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 99mTc-3PRGD2 chest SPECT images is highly accurate and feasible for SPECT without configuration with CT or treatment effect evaluation using multiple SPECT/CT scans.

Dynamic PET/CT scan of 68Ga-FAPI-04 for the optimal acquisition time in suspected malignant hepatic cancer patients.

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.

A deep learning-based post-processing method for automated pulmonary lobe and airway trees segmentation using chest CT images in PET/CT.

Background: The proposed algorithm could support accurate localization of lung disease. To develop and validate an automated deep learning model combined with a post-processing algorithm to segment six pulmonary anatomical regions in chest computed tomography (CT) images acquired during positron emission tomography/computed tomography (PET/CT) scans. The pulmonary regions have five pulmonary lobes and airway trees. Methods: Patients who underwent both PET/CT imaging with an extra chest CT scan were retrospectively enrolled. The pulmonary segmentation of six regions in CT was performed via a convolutional neural network (CNN) of DenseVNet architecture with some post-processing algorithms. Three evaluation metrics were used to assess the performance of this method, which combined deep learning and the post-processing method. The agreement between the combined model and ground truth segmentations in the test set was analyzed. Results: A total of 640 cases were enrolled. The combined model, which involved deep learning and post-processing methods, had a higher performance than the single deep learning model. In the test set, the all-lobes overall Dice coefficient, Hausdorff distance, and Jaccard coefficient were 0.972, 12.025 mm, and 0.948, respectively. The airway-tree Dice coefficient, Hausdorff distance, and Jaccard coefficient were 0.849, 32.076 mm, and 0.815, respectively. A good agreement was observed between our segmentation in every plot. Conclusions: The proposed model combining two methods can automatically segment five pulmonary lobes and airway trees on chest CT imaging in PET/CT. The performance of the combined model was higher than the single deep learning model in each region in the test set.

The Performance Comparison of 18F-FDG PET/MRI and 18F-FDG PET/CT for the Identification of Pancreatic Neoplasms.

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.

Preoperative prediction of pathological grade in pancreatic ductal adenocarcinoma based on 18F-FDG PET/CT radiomics.

PURPOSE: To develop and validate a machine learning model based on radiomic features derived from 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) images to preoperatively predict the pathological grade in patients with pancreatic ductal adenocarcinoma (PDAC). METHODS: A total of 149 patients (83 men, 66 women, mean age 61 years old) with pathologically proven PDAC and a preoperative 18F-FDG PET/CT scan between May 2009 and January 2016 were included in this retrospective study. The cohort of patients was divided into two separate groups for the training (99 patients) and validation (50 patients) in chronological order. Radiomics features were extracted from PET/CT images using Pyradiomics implemented in Python, and the XGBoost algorithm was used to build a prediction model. Conventional PET parameters, including standardized uptake value, metabolic tumor volume, and total lesion glycolysis, were also measured. The quality of the proposed model was appraised by means of receiver operating characteristics (ROC) and areas under the ROC curve (AUC). RESULTS: The prediction model based on a twelve-feature-combined radiomics signature could stratify PDAC patients into grade 1 and grade 2/3 groups with AUC of 0.994 in the training set and 0.921 in the validation set. CONCLUSION: The model developed is capable of predicting pathological differentiation grade of PDAC based on preoperative 18F-FDG PET/CT radiomics features.

A methodological investigation of healthy tissue, hepatocellular carcinoma, and other lesions with dynamic 68Ga-FAPI-04 PET/CT imaging.

BACKGROUND: The study aimed to establish a 68Ga-FAPI-04 kinetic model in hepatic lesions, to determine the potential role of kinetic parameters in the differentiation of hepatocellular carcinoma (HCC) from non-HCC lesions. MATERIAL AND METHODS: Time activity curves (TACs) were extracted from seven HCC lesions and five non-HCC lesions obtained from 68Ga-FAPI-04 dynamic positron emission tomography (PET) scans of eight patients. Three kinetic models were applied to the TACs, using image-derived hepatic artery and/or portal vein as input functions. The maximum standardized uptake value (SUVmax) was taken for the lesions, the hepatic artery, and for the portal veins-the mean SUV for all healthy regions. The optimum model was chosen after applying the Schwartz information criteria to the TACs, differences in model parameters between HCC, non-HCC lesions, and healthy tissue were evaluated with the ANOVA test. RESULTS: A reversible two-tissue compartment model using both the arterial as well as venous input function was most preferred and showed significant differences in the kinetic parameters VND, VT, and BPND between HCC, non-HCC lesions, and healthy regions (p < 0.01). CONCLUSION: Several model parameters derived from a two-tissue compartment kinetic model with two image-derived input function from vein and aorta and using SUVmax allow a differentiation between HCC and non-HCC lesions, obtained from dynamically performed PET scans using FAPI.

Fibroblast imaging of hepatic carcinoma with 68Ga-FAPI-04 PET/CT: a pilot study in patients with suspected hepatic nodules.

PURPOSE: 68Ga-FAPI-04 is a rapidly evolving PET tracer for whole-body imaging in a variety of cancers. We aimed to evaluate the diagnostic performance of 68Ga-FAPI-04 for detecting and characterizing hepatic nodules in patients with suspected carcinoma. METHODS: Twenty-five patients showing suspicious hepatic lesions for malignancy underwent 68Ga-FAPI-04 PET. The maximum and mean standardised uptake values (SUVmax, SUVmean) were measured for all detected lesions and normal hepatic tissues, respectively. The target-to-background ratio (TBR) was calculated by dividing the lesion SUVmax with the SUVmean of non-tumour liver tissue. Lesion uptake value was correlated with the in vitro hepatic FAP expression determined by immunohistochemistry (IHC). RESULTS: In total, 17 patients who underwent surgery or biopsy were recruited for the final analysis. A total of 28 intrahepatic malignant lesions were detected in 16 patients; the mean SUVmax was 8.36 ± 4.21 (range 2.21 to 15.86), and mean TBR was 13.15 ± 9.48 (range 2.79 to 38.12) in all detected lesions (n = 28). One benign patient showed negligible hepatic uptake (SUVmax = 0.47), whereas 75% of the primary intrahepatic hepatocellular carcinoma (HCC) lesions (n = 6) showed prominent FAP expression, 12.5% of the lesions (n = 1) showed moderate expression in stromal cells, and one showed negligible expression. CONCLUSIONS: 68Ga-FAPI-04 showed high sensitivity in detecting hepatic malignancies, particularly in poorly differentiated forms with concordantly elevated FAP expression.

Comparison of PET imaging of activated fibroblasts and 18F-FDG for diagnosis of primary hepatic tumours: a prospective pilot study.

PURPOSE: This study aimed to compare the performance of 68Ga-labelled fibroblast activating protein inhibitor (FAPI) PET and 18F-FDG PET for imaging of hepatic tumours. METHODS: We prospectively assessed 20 patients with suspected intrahepatic lesions. Tumour radiological features, pathology, or follow-up examinations were assessed as ground truth in correlation with PET scans. Semiquantitative analysis was additionally performed by measuring the standardised uptake value (SUV). Tumour-to-liver background ratios (TBR) were calculated and compared between 68Ga-FAPI PET and 18F-FDG PET. FAPI expression was assessed by immunochemistry in samples obtained from 7 patients with hepatocellular carcinomas (HCC)/intrahepatic cholangiocarcinoma (ICC) or granulomas. RESULTS: Primary intrahepatic tumours, including 16 HCC in 14 patients and 4 ICC in 3 patients with extrahepatic metastases, were determined by histology (n = 14) and clinical examinations (n = 3). Based on visual analysis, 17 patients presented elevated 68Ga-FAPI uptake (sensitivity: 100%, specificity: 100%), while 7 patients presented 18F-FDG avid tumours (sensitivity: 58.8%, specificity: 100%). 68Ga-FAPI PET/CT identified 17 extrahepatic metastases vs. 13 in 18F-FDG PET/CT in 2 ICC patients. Three benign liver nodules in three patients showed negligible uptake in dual-PET scans. The SUVmax_HCC = 8.47 ± 4.06 and TBRmax_HCC = 7.13 ± 5.52, and SUVmax_ICC = 14.14 ± 2.20 TBRmax_ICC = 26.46 ± 4.94 in 68Ga-FAPI-04 PET/CT were significantly higher than the 18F-FDG uptake presenting SUVmax_HCC = 4.86 ± 3.58 and TBRmax_HCC = 2.39 ± 2.21, and SUVmax_ICC = 9.19 ± 3.60 and TBRmax_ICC = 2.39 ± 2.21 (all p values < 0.05). ICC patients showed higher levels of FAPI uptake in the primary hepatic lesions compared to extrahepatic metastases, TBRmax_ICC = 15.18 ± 5.80 (p = 0.04). CONCLUSIONS: 68Ga-FAPI PET-CT has superior potential in the detection of primary hepatic malignancy compared to 18F-FDG.

Comparative [18F]FDG and [18F]DPA714 PET imaging and time-dependent changes of brown adipose tissue in tumour-bearing mice.

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 [18F]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 ([18F]FDG) and [18F]DPA714. We also studied the BAT uptake of [18F]DPA714 in CT26, A549 and LLC tumor models. The dynamic distribution of [18F]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, [18F]DPA714 produced high-quality and stable BAT imaging in different tumor models and different animals of the same model. Interestingly, %ID/g-mean of [18F]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 [18F]DPA714 PET imaging in investigating BAT and energy metabolism during tumor progression in preclinical and clinical study.

Application of integrated positron emission tomography/magnetic resonance imaging in evaluating the prognostic factors of head and neck squamous cell carcinoma with positron emission tomography, diffusion-weighted imaging, dynamic contrast enhancement and combined model.

OBJECTIVES: 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). METHODS: 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. RESULTS: 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. CONCLUSIONS: Compared with the independent parameter, the combination of multiple parameters with PET/MR can further improve the diagnostic performance of tumour differentiation in HNSCC.

PET-MR Imaging and MR Texture Analysis in the Diagnosis of Pancreatic Cysts: A Prospective Preliminary Study.

RATIONALE AND OBJECTIVES: Our aim was to evaluate the capability of textural and metabolic parameters measured at pretreatment 18F-fluorodeoxyglucose Positron emission tomography (PET)-MR in differentiating malignant from benign pancreatic cystic lesions. MATERIALS AND METHOD: Forty consecutive patients were prospectively enrolled in this study. They underwent simultaneous PET-MR for the diagnosis of pancreatic cysts. Thirty texture parameters were extracted from manually contoured axial T2-weighted imaging with fat suppression (T2FS) and apparent diffusion coefficient images, respectively. Maximal and mean standardized uptake values (SUVmax and SUVmean, respectively) of pancreatic cysts were measured at PET-MR imaging. The Mann-Whitney test was used to compare both textural and metabolic parameters between benign and malignant group. RESULTS: FDG uptake was significantly higher in patients with malignant pancreatic cysts (SUVmaxp = 0.002, SUVmeanp < 0.001). Malignant cysts showed significantly lower standard deviation for spatial scaling factor at 3-6mm on T2FS images and lower skewness for spatial scaling factor at 2-4mm on apparent diffusion coefficient images (p < 0.01). SUVmean had the highest Area under the curve of 0.892 on receiver-operating characteristic analysis with a sensitivity, specificity, and accuracy of 88.9%, 87.1%, and 87.6%, respectively. When metabolic and textural features were combined into a single diagnostic model, the AUC increased to 0.961, with a sensitivity, specificity, and accuracy of 88.9%, 96.8%, and 95.0%, respectively. CONCLUSION: Our study implied that PET-MR showed no obvious advantages over traditional PET-related imaging in differentiating malignant from benign pancreatic cystic lesions. Diagnostic model based on the combination of metabolic and textural parameters showed satisfactory performance.

Incidental Detection of Adenocarcinoma in the Neck of the Pancreas by FDG PET Imaging When a Cystic Lesion in the Body of Pancreas Was Evaluated.

FDG PET/CT and PET/MRI were performed to evaluate a cystic lesion in the body of the pancreas in a 65-year-old man. Neither studies showed abnormally increased activity in the cystic lesion in the body of the pancreas. However, both studies revealed abnormal activity in the neck of the pancreas, which did not show anatomical abnormality and was not suspected prior to the PET imaging. Pathological examination demonstrated that the lesion in the body of the pancreas was a benign duct dilation, whereas the abnormal FDG activity in the neck of the pancreas was due to pancreatic adenocarcinoma.

Focal Autoimmune Pancreatitis Mimicking Pancreatic Cancer on FDG PET/CT Imaging.

Autoimmune pancreatitis generally results in diffuse increased FDG activity throughout the pancreas on PET/CT images. We present a case of focal autoimmune pancreatitis with abnormal FDG activity involving only the pancreatic tail on PET/CT in a 61-year-old man who was provisionally diagnosed as having pancreatic cancer based on the CT findings. The diagnosis of autoimmune pancreatitis was based on pathological examination and elevated serum immunoglobulin G4 level. Following the steroid therapy, the patient was gradually recovered.

Biodistribution and Radiation Dosimetry of the Enterobacteriaceae-Specific Imaging Probe [(18)F]Fluorodeoxysorbitol Determined by PET/CT in Healthy Human Volunteers.

PURPOSE: [(18)F]fluorodeoxysorbitol ([(18)F]FDS) is the first radiopharmaceutical specific for a category of bacteria and has the potential to specifically detect Enterobacteriaceae infections. The purpose of this study was to testify the safety and investigate the biodistribution and radiation dosimetry of [(18)F]FDS in healthy human bodies. PROCEDURES: Six healthy subjects were intravenously injected with 320-520 MBq [(18)F]FDS. On each subject, 21 whole-body emission scans and a brain scan were conducted at settled time points within the next 4 h. Residence time for each source organ was determined by multi-exponential regression. Absorbed doses for target organs and effective dose were calculated via OLINDA/EXM. RESULTS: No adverse events due to [(18)F]FDS injection were observed in the study. The tracer was cleared rapidly from the blood pool through the urinary system. A small portion was cleared into the gut through the hepatobiliary system. The effective dose (ED) was estimated to be 0.021 ± 0.001 mSv/MBq. The organ receiving the highest absorbed dose was the urinary bladder wall (0.25 ± 0.03 mSv/MBq). CONCLUSIONS: [(18)F]FDS is safe and well tolerated. The effective dose was comparable to that of other F-18 labeled radiotracers. [(18)F]FDS is suitable for human use from a radiation dosimetry perspective.

[Features of Acquired Immunodeficiency Syndrome-related Lymphoma on (18)F-fluorodeoxyglucose Positron Emission Tomography/Computed Tomography].

OBJECTIVE: To analyze the imaging features of (18)F-fluorodeoxyglucose (¹8F-FDG) positron emission tomography(PET)/computed tomography (CT) in acquired immune deficiency syndrome-related lymphoma (ARL) patients correlated with their clinical signs, symptoms, and treatments. METHODS: Five ARL patients underwent ¹8F-FDG PET/CT at Peking Union Medical College Hospital from October 2008 to January 2013. Two patients received two additional follow-up studies 6 months later. RESULTS: Among these 5 patients, ¹8FDG-PET/CT helped in diagnosis of two patient and changed therapeutic strategy in other two patients. In two patients underwent ¹8F-FDG PET/CT brain scans, low-metabolism lesion was newly found in cerebral cortex. Of 4 patients receiving highly active antiretroviral therapy, PET/CT also demonstrated diffusely elevated ¹8F-FDG uptake in subcutaneous adipose tissue in two patients. CONCLUSION: ¹8F-FDG PET/CT is a highly useful tool in the diagnosis and treatment of ARL patients, in particular in the identification of associated encephalopathy and lipodystrophy.

68Ga DOTATATE PET/CT is an Accurate Imaging Modality in the Detection of Culprit Tumors Causing Osteomalacia.

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.

99mTc-HYNIC-TOC imaging in the evaluation of pancreatic masses which are potential neuroendocrine tumors.

PURPOSE: The aim of this investigation was to determine the accuracy of the findings and the diagnoses of Tc-hydrazinonicotinyl-Tyr3-octreotide scan (Tc-HYNIC-TOC imaging) in patients with pancreatic masses which were potential neuroendocrine tumors. METHODS: Records of total 20 patients with pancreatic masses were retrospectively reviewed. All of the patients had been revealed by abdominal contrast CT and possibility of neuroendocrine tumors could not be excluded by CT imaging before Tc-HYNIC-TOC imaging. Tc-HYNIC-TOC imaging was performed at 1 and 4 hours post-tracer injection, and SPECT/CT images of the abdomen were also acquired. The image findings were compared to final diagnoses which were made from pathological examination. RESULTS: Among all 20 pancreatic masses evaluated, there were 16 malignant lesions which included 1 ductal adenocarcinoma and 15 neuroendocrine tumors. Tc-HYNIC-TOC imaging identified 14 of 15 pancreatic neuroendocrine tumors and excluded 4 of 5 lesions which were not neuroendocrine tumors. The overall sensitivity, specificity, and accuracy was therefore 93.3% (14 of 15), 80% (4 of 5), and 90.0% (18 of 20), respectively, in our patient population. CONCLUSION: Tc-HYNIC-TOC imaging provides reasonable accuracy in the evaluation pancreatic mass suspected to be neuroendocrine tumors.

Application of dual phase imaging of 11C-acetate positron emission tomography on differential diagnosis of small hepatic lesions.

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.