Diagnostic efficiency of [68 Ga]Ga-DOTA-FAPI-04 in differentiating periprosthetic hip joint infection and aseptic failure.

PURPOSE: To assess the efficiency of [68 Ga]Ga-DOTA-FAPI-04 in diagnosing periprosthetic hip joint infection and establish a diagnostic standard of clinical significance based on uptake pattern. METHODS: [68 Ga]Ga-DOTA-FAPI-04 PET/CT was performed in patients with symptomatic hip arthroplasty from December 2019 to July 2022. The reference standard was based on the 2018 Evidence-Based and Validation Criteria. Two diagnostic criteria, SUVmax and uptake pattern, were used to diagnose PJI. Meanwhile, original data were imported into IKT-snap to draw the view of interest, A.K. was used to extract features of clinical cases, and unsupervised clustering analysis was applied according to the groups. RESULTS: A total of 103 patients were included, 28 of whom had PJI. The area under the curve of SUVmax was 0.898, which was better than that of all of the serological tests. The cutoff value of SUVmax was 7.53, and the sensitivity and specificity were 100 and 72%, respectively. The sensitivity, specificity and accuracy of the uptake pattern were 100, 93.1 and 95%, respectively. In radiomics analysis, the features of PJI were significantly different from those of aseptic failure. CONCLUSION: The efficiency of [68 Ga]Ga-DOTA-FAPI-04 PET/CT in diagnosing PJI showed promising results, and the diagnostic criteria of the uptake pattern were more clinically instructive. Radiomics also showed certain application prospects in the field of PJI. TRIAL REGISTRATION NUMBER: Trial registration: ChiCTR2000041204. Registered 24 September 2019.

Control of agitation and aeration rates in the production of surfactin in foam overflowing fed-batch culture with industrial fermentation.

Bacillus amyloliquefaciens fmb50 produces a high yield of surfactin, a lipopeptide-type biosurfactant that has been widely studied and has potential applications in many fields. A foam overflowing culture has been successfully used in the combined production-enrichment fermentation of surfactin. In this study, the agitation and aeration rates were found to have relationships with foam formation and surfactin enrichment. A maximum surfactin concentration of 4.7g/l of foam was obtained after 21h of culture with an agitation rate of 150rpm and an aeration rate of 1vvm in fed-batch culture. By controlling the foam overflow rate (fout) of a fed-batch culture, surfactin concentration in the foam was continuously maintained above 4g/l.

Mining and evaluation of new specific molecular targets for the PCR detection of Salmonella spp. genome.

The purpose of this study is to find new molecular targets for the detection of Salmonella. With the online BLAST Program, we compared homology of genomic sequences and specificity in GenBank among Salmonella serovars and non-Salmonella strains and found 98 Salmonella specific target sequences. We selected 33 target sequences of Gene ID from 3335000 to 3337003 for the specificity evaluation, and finally 8 specific fragments screened out, they are 3334138, 3335583, 3335471, 3335211, 3335068, 3336466, 3336736 and 3336998. Primer SC8 of gene 3335583 and SC9 of gene 3335471 were the best in specificity and sensitivity among these primers. The detection sensitivity of Primer SC9 was 1.23 fg/µl for DNA templates and 720 cfu/ml for whole cells, while primer SC8's was 12.3 fg/µl and 720 cfu/ml, respectively. Salmonella could be detected successfully by the PCR method developed in this study after 8 h enrichment when the milk samples were artificially contaminated by this organism at 7 cfu per 10 ml milk.

Synthesis and Preclinical Evaluation of 2-(4-[18F]Fluorophenyl)imidazo[1,2-h][1,7]naphthyridine ([18F]FPND-4): An Aza-Fused Tricyclic Derivative as Positron Emission Tomography Tracer for Neurofibrillary Tangle Imaging.

Tau accumulation is one of the predominant neuropathological biomarkers for in vivo diagnosis of Alzheimer's disease due to its high correlation with disease progression. In this study, we focused on the structure-activity relationship study of the substituent effect on the aza-fused tricyclic core imidazo[1,2-h][1,7]naphthyridine to screen 18F-labeled Tau tracers. Through a series of autoradiographic studies and biological evaluations, 4-[18F]fluorophenyl-substituted tracer [18F]13 ([18F]FPND-4) was identified as a promising candidate with high affinity to native Tau tangles (IC50 = 2.80 nM), few appreciable binding to Aß plaques and MAO-A/B. Validated by dynamic positron emission tomography (PET) imaging in rodents and rhesus monkey, [18F]13 displayed desirable brain uptake (SUV = 1.75 at 2 min), fast clearance (brain2min/60min = 5.9), minimal defluorination, and few off-target binding, which met the requirements of a Tau-specific PET radiotracer.

Evaluation of short-term effects of drug-loaded microspheres and traditional transcatheter arterial chemoembolization in the treatment of advanced liver cancer.

BACKGROUND: Liver cancer is a malignant tumor with high morbidity and mortality. Transcatheter arterial chemoembolization (TACE) is the main method for surgically unresectable liver cancer. In recent years, drug-loaded microspheres have been gradually applied in TACE technology. There are some controversies about the therapeutic effects of drug-loaded microspheres TACE (D-TACE) and traditional TACE. AIM: To explore the short-term efficacy of D-TACE and traditional TACE in the treatment of advanced liver cancer. METHODS: The clinical data of 73 patients with advanced liver cancer admitted to the First and Sixth Medical Centers of Chinese PLA General Hospital from January 2017 to October 2019 were retrospectively analyzed. Among them, 15 patients were treated with D-TACE, and 58 patients were treated with traditional TACE. Clinical baseline characteristics, perioperative laboratory indices, postoperative adverse reactions and postoperative complications were compared between the two groups. RESULTS: There was no statistical difference between the two groups for the postoperative response: The highest postoperative body temperature of the drug-loaded microsphere group was 38.0 ± 0.9℃ and the postoperative highest body temperature of the traditional TACE group was 38.3 ± 0.7℃ (t = -1.414, P = 0.162). For the 24 h postoperative nausea and vomiting after surgery in terms of scoring and postoperative pain scores, the traditional TACE group was higher than the drug-loaded microsphere group (χ 2 = 14.33, P = 0.014; χ 2 = 32.967, P = 0.000) and the two groups had significant statistical differences. The disease control rate at 3 mo after treatment in the drug-loaded microsphere group was 60% and the disease control rate at 3 mo after treatment in the traditional TACE group was 75.9% (χ 2 = 4.091, P = 0.252). There was no statistical difference between the two groups of data. During the follow-up period, the number of interventional treatments received was once in the drug-loaded microsphere group and the traditional TACE group received an average of 1.48 treatments (χ 2 = 10.444 P = 0.005). There was a statistical difference between the two groups. CONCLUSION: Compared with traditional TACE, D-TACE may have some advantages in the treatment of advanced hepatocellular carcinoma with a large tumor load in the short term, but the long-term clinical efficacy needs additional follow-up studies. In addition, compared with the traditional group, the patients in the drug-loaded microsphere group had better subjective tolerance and could reduce the number of interventional treatments. Therefore, D-TACE is worthy of clinical promotion.

The Combination of 18F-Fluorodeoxyglucose Positron Emission Tomography Metabolic and Clinical Parameters Can Effectively Distinguish Rheumatoid Arthritis and Polymyalgia Rheumatic.

Objective: To evaluate 18F-fluorodeoxyglucose positron emission tomography (18FDG PET) and clinical parameters to differentiate rheumatoid arthritis (RA) and polymyalgia rheumatic (PMR). Patients and Methods. This retrospective study evaluated 54 patients with suspected RA (n = 23) and PMR (n = 31) who underwent 18F-FDG PET/CT before treatment. The complete diagnosis was based on each classification criterion and at least followed up for 6 months. Demographic and clinical data were also collected. Semiquantitative analysis (maximum standardized uptake value, SUVmax) of abnormal 18F-FDG uptake was undertaken at 17 musculoskeletal sites, and two scoring systems (mean reference (liver/control) scores) were evaluated. The differential diagnostic efficacy of each independent parameter was evaluated using the receiver operating characteristic (ROC) curve. Integrated discriminatory improvement (IDI) and bootstrap tests were used to evaluate the improvement in diagnostic efficacy using a combination of multiple parameters. Results: The ROC curve analysis of SUVmax indicated that the interspinous ligament showed the highest discriminative diagnostic value (sensitivity, 64.5%; specificity, 78.3%; area under the curve (AUC), 0.764; positive predictive value, 0.800; negative predictive value, 0.621). The combined model with the rheumatoid factor (RF) and metabolic parameters of 18F-FDG PET resulted in the highest AUC of 0.892 and showed significant reclassification by IDI (IDI, 9.51%; 95% confidence interval: 0.021-0.175; P = 0.013). According to the bootstrap test, compared with RF alone, the combination of RF and metabolic parameters showed an improvement in ROC and was statistically significant (P = 0.017). Conclusions: The combination of 18F-FDG PET metabolic and clinical parameters can further improve the differential diagnosis of RA and PMR.

Using 18F-flurodeoxyglucose and 68Ga-fibroblast activation protein inhibitor PET/CT to evaluate a new periprosthetic joint infection model of rabbit due to Staphylococcus aureus.

PURPOSE: The existing periprosthetic joint infection (PJI) models have obvious limitations, and studies of PJI on animal models using PET/computed tomography (CT) for diagnosis are still lacking. Thus, the aim of this study was to establish a new PJI model and 18F-fluorodeoxyglucose (FDG) and 68Ga-fibroblast activation protein inhibitor (FAPI) were employed to study their performance. METHODS: A novel PJI model of rabbit was developed by placing two screws in the tibia and femur. Based on bacteria concentration, the animals were divided into five groups, control, 104, 105, 106 and 107. 18F-FDG and 68Ga-FAPI PET/CT were performed continuously in next 2 weeks and maximum standardized uptake value (SUVmax), mean standardized uptake value (SUVmean), metabolic target volume (MTV) and total lesion glycolysis/total lesion fibrosis were calculated as the metrics. RESULTS: As for SUVmax, all data of 18F-FDG were larger than that of 68Ga-FAPI in the same group for both weeks. For the performance of 18F-FDG, no definitive conclusion could be drawn for SUVmax and SUVmean. As for 68Ga-FAPI, the 104 group was significantly larger than 105, 106 and 107 groups for SUVmax and SUVmean in both weeks (P < 0.05). MTV of 68Ga-FAPI was found to be almost always larger than that of 18F-FDG in the same group. CONCLUSION: The mechanism of 68Ga-FAPI is totally different from 18F-FDG and this unique property of 68Ga-FAPI shows a promising prospect in detecting infection boundary and may even distinguish a small number or a large number of bacterial infections.

Pretreatment Metabolic Parameters Measured by 18F-FDG PET to Predict the Pathological Treatment Response of HCC Patients Treated With PD-1 Inhibitors and Lenvatinib as a Conversion Therapy in BCLC Stage C.

Objectives: This study aimed to assess the pretreatment 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) as a predictor of the pathological treatment response (PTR) of hepatocellular carcinoma (HCC) patients treated with PD-1 inhibitors and lenvatinib as a conversion therapy in BCLC stage C. Methods: All patients (n=20) underwent pretreatment 18F-FDG PET/CT and were treated with conversion therapy and surgery. Patients were categorized into responders (n=9) and non-responders (n=11) according to PTR. The parameters of PET/CT, including lesion size, SUVmean (mean standard uptake value), MTV (metabolic tumor volume), TLG (total lesion glycolysis), SUVpeak (peak standard uptake value), and TLR (tumor-to-normal liver standardized uptake value ratio), were calculated. The diagnostic efficacy was evaluated by receiver operating characteristic analysis (ROC). PTR was compared with pretreatment PET/CT parameters by using Spearman correlation analysis. The patients were followed up. Results: There was significant difference in TLR (5.59 ± 1.90 vs. 2.84 ± 1.70, respectively; P=0.003) between responders and non-responders, with the largest area under the curve (sensitivity=100%, specificity=72.7%, AUC=0.899, 95%CI: 0.759-1.000, optimal diagnostic threshold of 3.09). The relationship between 18F-FDG PET/CT parameters and PTR indicated TLR was moderately and positively correlated with pathological treatment response, with correlation coefficients (rs) of 0.69 (P<0.01). During the follow-up, no patients died, and tumor recurrence was found in one of the responders (11.1%). In all 11 non-responders, tumor recurrence was found in six patients (54.5%) and four patients (36.4%) died. Conclusions: TLR may be a powerful marker to predict PTR of HCC patients with BCLC stage C who were treated with conversion therapy.

Performance characteristics of 18F-fluorodeoxyglucose in non-infected hip replacement.

Purpose: The aim of this study was to retrospectively analyze 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET)/ computed tomography (CT) images of non-infected hip arthroplasty patients and summarize findings that may be useful for clinical practice. Methods: 18F-FDG PET/CT images of non-infected hip arthroplasty patients were collected from September 2009 to August 2021. The region of interest was independently delineated by two physicians and maximum standardized uptake values (SUVmax) were recorded and compared. Serologic data were also collected and the correlation between SUVmax and serologic parameters was analyzed, while the images were classified based on the 18F-FDG uptake pattern in the images using the diagnostic criteria proposed by Reinartz et al. (9). The interval between hip replacement and PET/CT was classified by year and the characteristics of the two groups were compared. The images of patients who underwent PET/CT multiple times were analyzed dynamically. Results: A total of 121 examinations were included; six patients underwent PET/CT twice and two patients had three scans. There were no significant correlations between SUVmax and serologic results. The interobserver agreement between the two physicians in the classification according to the criteria of Reinartz et al. (9) was 0.957 (P < 0.005). Although there was non-specific uptake in cases with an arthroplasty-to-PET/CT interval this was non-significant. Additionally, 18F-FDG showed potential utility for dynamic observation of the condition of the hip. Conclusion: SUVmax provided information independent of serologic results, meanwhile 18F-FDG showed potential applicability to the dynamic monitoring of hip arthroplasty-related diseases. However, the presence of blood vessels and muscles affected image interpretation and the specificity of 18F-FDG was not optimal. A more specific radionuclide is needed to maximize the benefits of using PET/CT for the assessment of periprosthetic joint infection (PJI).

Can multimodality imaging using 18F-FDG/18F-FLT PET/CT benefit the diagnosis and management of patients with pulmonary lesions?

PURPOSE: Dual-tracer, (18)F-fluorodeoxyglucose and (18)F-fluorodeoxythymidine ((18)F-FDG/(18)F-FLT), dual-modality (positron emission tomography and computed tomography, PET/CT) imaging was used in a clinical trial on differentiation of pulmonary nodules. The aims of this trial were to investigate if multimodality imaging is of advantage and to what extent it could benefit the patients in real clinical settings. METHODS: Seventy-three subjects in whom it was difficult to establish the diagnosis and determine management of their pulmonary lesions were prospectively enrolled in this clinical trial. All subjects underwent (18)F-FDG and (18)F-FLT PET/CT imaging sequentially. The images were interpreted with different strategies as either individual or combined modalities. The pathological or clinical evidence during a follow-up period of more than 22 months served as the standard of truth. The diagnostic performance of each interpretation and their impact on clinical decision making was investigated. RESULTS: (18)F-FLT/(18)F-FDG PET/CT was proven to be of clinical value in improving the diagnostic confidence in 28 lung tumours, 18 tuberculoses and 27 other benign lesions. The ratio between maximum standardized uptake values of (18)F-FLT and (18)F-FDG was found to be of great potential in separating the three subgroups of patients. The advantage could only be obtained with the full use of the multimodality interpretation. Multimodality imaging induced substantial change in clinical management in 31.5% of the study subjects and partial change in another 12.3%. CONCLUSION: Multimodality imaging using (18)F-FDG/(18)F-FLT PET/CT provided the best diagnostic efficacy and the opportunity for better management in this group of clinically challenging patients with pulmonary lesions.

Synthesis, Preclinical Evaluation, and First-in-Human PET Study of Quinoline-Containing PSMA Tracers with Decreased Renal Excretion.

The prostate-specific membrane antigen (PSMA) is considered to be an excellent theranostic target of prostate cancer (PCa). In this study, three 18F-labeled PSMA tracers with a more lipophilic quinoline functional spacer were designed, synthesized, and evaluated based on the Glu-Ureido-Lys binding motif. The effect of structure-related lipophilic difference on distribution and excretion of these tracers in vitro and in vivo (cells, rodent, primate, and human) was investigated by comparing with [18F]DCFPyL. There is no significant correlation between the renal elimination and the lipophilicity of the tracers in all species. However, the higher the lipophilicity of tracer, the higher the radioactivity accumulation in the liver of primate and human, and the less radioactivity is to excrete to the bladder with urine. The screened tracer [18F]8c, with a Ki value of 4.58 nM, displayed notable low bladder retention and demonstrated good imaging properties in patients with PCa.

Analysis of the F-18 FDG PET/CT features of pulmonary sclerosing pneumocytoma.

PURPOSE: This retrospective study aimed to analyzed the F-18 fluorodeoxyglucose PET/computed tomography (F-18 FDG PET/CT) features of pulmonary sclerosing pneumocytoma (PSP) to improve the understanding and preoperative diagnostic efficacy of this rare disorder. METHODS: FDG PET/CT images from 11 patients with 22 lesions (including one patient with 12 lesions) proven PSP in our hospital were reviewed. We summarized the PET/CT features of PSP and analyzed the correlation between FDG uptake and tumor size. RESULTS: PET/CT imaging revealed all tumors located in each lobe of the two lungs randomly. All 22 tumors were round or oval nodules; 15 had smooth margins, six were lobulated, six were calcified, and one had a ground-glass halo sign. The mean diameter of these tumors was 19.2 ± 7.8 mm (range: 8-34 mm); the mean maximum standardized uptake value (SUVmax) was 2.8 ± 1.3 (range: 1.1-7.4). Sixteen of the lesions exhibited mild to moderate FDG uptake (mean SUVmax 2.3 ± 0.6), and six of the lesions exhibited intense FDG uptake (mean SUVmax 4.3 ± 1.6). A positive correlation was observed between FDG uptake and tumor size (P <0.05). CONCLUSION: Single round or ovoid soft-tissue lesions with smooth margins, and mild to moderate FDG uptake on PET/CT images in middle-aged females, suggest a possible diagnosis of PSP. For some atypical cases with intense FDG uptake, a diagnosis of PSP also can be considered. A statistically significant positive correlation was found between SUVmax and PSP lesion size in our study.

Simplified protocol for whole-body Patlak parametric imaging with 18 F-FDG PET/CT: Feasibility and error analysis.

PURPOSE: Parametric imaging using the Patlak model has been shown to provide improved lesion detectability and specificity. The Patlak model requires both tissue time-activity curves (TACs) after equilibrium and knowledge of the input function from the start of injection. Therefore, the conventional dynamic scanning protocol typically starts from the radiotracer injection all the way to equilibrium. In this paper, we propose the use of hybrid population-based and model-based input function estimation and evaluate its use for whole-body Patlak analysis, in order to reduce the total scan time and simplify clinical Patlak parametric imaging protocols. Possible quantitative errors caused by the simplified scanning protocol were also analyzed both theoretically and with the use of clinical data. MATERIALS AND METHODS: Clinical data from 24 patients referred for tumor staging were included in this study. The patients underwent a whole-body dynamic PET study, 20 min after FDG injection (0.13 mCi/kg). The proposed whole-body scanning protocol includes 6 passes with 4-5 bed positions, depending on the size of the patient, with 2 min for each bed position. An input function from the literature was selected as the shape of the population-based input function. The descending aorta from the corresponding CT image was segmented and applied on the reconstructed dynamic PET images to acquire an image-based input function, which was later fitted using an exponential model. Due to the late scan time, only the later portion of the input function was available, which was used to scale the population-based input function. The hybrid input function was used to derive the whole-body Patlak images. Assuming a given error in the population-based input function, its influence on the final Patlak images were also derived theoretically and verified using the clinical data sets. Finally, the image quality of the reconstructed Patlak slope image was evaluated by an experienced radiologist in four different aspects: image artifacts, image noise, lesion sharpness, and lesion detectability. RESULTS: It was found that errors in the population-based input function only affect the absolute scale of the Patlak slope image. The induced error is proportional to the percentage area-under-curve (AUC) error in the input function. These findings were also confirmed by numerical analysis. The predicted global scale was in good agreement with results from both image-based Patlak and direct Patlak approach. The fractions of the AUC from the early portion population-based input function were also found to be around 18% of the total AUC of the input function, further limiting the propagation of quantitation error from population-based input function to the final Patlak slope image. The reconstructed Patlak images were also found by the radiologist to provide excellent confidence in lesion detection tasks. CONCLUSIONS: We have proposed a simplified whole-body scanning protocol that utilizes both population-based input function and model-based input function. The error from the population-based function was found to only affect the global scale and the overall quantitative impact can be predicted using our proposed formulas.

Deep learning-based image reconstruction for TOF PET with DIRECT data partitioning format.

Conventional positron emission tomography (PET) image reconstruction is achieved by the statistical iterative method. Deep learning provides another opportunity for speeding up the image reconstruction process. However, conventional deep learning-based image reconstruction requires a fully connected network for learning the Radon transform. The use of fully connected networks greatly complicated the network and increased hardware cost. In this study, we proposed a novel deep learning-based image reconstruction method by utilizing the DIRECT data partitioning method. The U-net structure with only convolutional layers was used in our approach. Patch-based model training and testing were used to achieve 3D reconstructions within current hardware limitations. Time-of-flight (TOF)-histoimages were first generated from the listmode data to replace conventional sinograms. Different projection angles were used as different channels in the input. A total of 15 patient data were used in this study. For each patient, the dynamic whole-body scanning protocol was used to expand the training dataset and a total of 372 separate scans were included. The leave-one-patient-out validation method was used. Two separate studies were carried out. In the first study, the measured TOF-histoimages were directly used for model training and testing, to study the performance of the method in real-world applications. In the second study, TOF-histoimages were simulated from already reconstructed images to exclude the scatters, randoms, attenuation-activity mismatch effects. This study was used to evaluate the optimal performance when all other corrections are ideal. Volumes of interests were placed in the liver and lesion region to study image noise and lesion quantitations. The reconstructed images using the proposed deep learning method showed similar image quality when compared with the conventional expectation-maximization approach. A minimal difference was observed when the simulated TOF-histoimages were used as model input and testing, suggesting the deep learning model can indeed learn the reconstruction process. Some quantitative difference was observed when the measured TOF-histoimages were used. The two studies suggested that the major difference is caused by inaccurate corrections performed by the network itself, which indicated that physics-based corrections are still required for better quantitative performance. In conclusion, we have proposed a novel deep learning-based image reconstruction method for TOF PET. With the help of the DIRECT data partitioning method, no fully connected layers were used and 3D image reconstruction can be directly achieved within the limits of the current hardware.

Multiparameter Analysis Using 18F-FDG PET/CT in the Differential Diagnosis of Pancreatic Cystic Neoplasms.

Purpose: To evaluate multiparametric analysis in differential diagnosis between pancreatic serous cystic neoplasms (SCNs) and mucinous cystic neoplasms (MCNs) as well as the differentiation of the benign and malignant MCNs with 18F-FDG (18-fluorodeoxyglucose) PET/CT (positron emission tomography). Methods: Forty patients with total of 41 lesions (SCNs: 27/41; MCNs: 14/41), who were preoperatively examined with 18F-FDG PET/CT, were retrospectively analyzed. Multiple quantitative parameters using conventional and texture features were included. The combined model was established with complementary PET/MR parameters. The differential diagnostic efficacy of each independent parameter and the combined model were evaluated with receiver operating characteristic (ROC) analysis. Integrated discriminatory improvement (IDI) and net reclassification improvement (NRI) were used to evaluate improvement of diagnostic efficacy by using combination of multiple parameters. Results: Among all independent parameters, the percentile 5th (0.88 ± 0.38 vs 0.47 ± 0.23, P < 0.001) showed the highest discriminative diagnostic value. The combination of multiple parameters can improve the differential diagnostic efficacy of SCNs and MCNs (sensitivity = 71.4%, specificity = 77.8%, and AUC = 0.788), and the addition of texture parameters to the conventional parameters allowed a significant reclassification with IDI = 0.236 (95% CI: 0.095-0.377) and categorical NRI = 0.434 (95% CI: 0.030-0.838). SURmax (tumor to normal pancreas ratio, T/P) and SURmax (tumor to aorta ratio, T/A) both showed the highest discriminative diagnostic value (sensitivity = 100.0%, specificity = 70.0%, AUC = 0.900, and Youden index = 0.700) in the differential diagnosis of benign and malignant MCNs, with the cutoff values of 0.84 and 0.90, respectively. Conclusion: Combination of multiple parameters using 18F-FDG PET/CT could further improve differentiation between pancreatic SCNs and MCNs. SURmax (T/P) and SURmax (T/A) could improve differential diagnosis of benign and malignant MCNs.

[Application of positron emission tomography in evaluation of Alzheimer's disease rat model].

OBJECTIVE: To discuss the value of 11C-PIB PET and 18F-FDG micro PET imaging in Alzheimer's disease (AD) rat model. METHODS: The AD rat model was established by injection of Abeta1-40 into rat's hippocampus. Learning and memory function were estimated by the Morris water maze. Amyloid deposit and neuron loss were observed by Congo red staining and HE staining respectively. 11C-PIB PET and 18F-FDG micro PET scan were performed. Meanwhile the findings of PET imaging were compared with the results of behavior test and histology. RESULTS: The uptake of 18F-FDG in hippocampus of AD rat model group was lower than that of control group (P < 0.01). The Morris water maze showed that the escape latent period of rat model group was longer than that of control group (P < 0.01). Neuron loss was found in rat model brain. Thus the result of micro-PET imaging was matched with those of the Morris water maze and HE staining. 11C-PIB was specifically bound to beta-amyloid in rat model brain, the uptake of 11C-PIB in AD rat model was higher than that of control (P < 0.05). Abeta deposit was observed in Congo red staining so that the result of 11C-PIB Micro-PET imaging was matched with that of beta-amyloid deposition. CONCLUSION: 11C-PIB Micro-PET imaging shows the plaque deposition while 18F-FDG PET imaging reflects the change of glucose metabolism in hippocampus in AD rat model. And PET scan can be used to verify the successful establishment of AD model rat model.

[Positron emission tomography imaging of cell transplantation in a rat model of Alzheimer's disease].

OBJECTIVE: To explore the value of positron emission tomography (PET) in the Alzheimer's disease (AD) rat model verification and in monitoring the therapeutic effectiveness of cell transplantation. METHODS: A beta(1-40) hippocampus injected rat model was successfully established and neural stem cells were injected into hippocampus. Results of behavior tests and histological examinations were compared between model group and graft group, and then the N-methyl-[(11)C]2-(4 methylaminophenyl)-6-hydroxybenzothiazole ((11)C-PIB) and (18)F-fluorodeoxyglucose ((18)F-FDG) imaging were performed to observe whether the result of imaging was matched with behavior test and histological examination. RESULTS: The Morris water maze showed that the latent period of the escape was significantly longer in model group than in control group (P<0.01). In histological examinations, the neuron loss and A beta deposition were found in hippocampus CA1 and dentate gyrus of rat model. (11)C-PIB imaging showed increased uptake in model rat hippocampus district (P<0.05), while (18)F-FDG imaging showed that the uptake in the injected side of hippocampus in model group was significantly lower than that in the same side in control group (P<0.001). After cell transplantation, the latent period of the escape was significantly shorter in graft group than in model group (P<0.01). Histological examinations showed that there was no obvious changes in A beta deposition; in addition, the neural stem cells differentiated and expressed neuronal nuclei-positive cells, and continuously expressed 5-bromodeoxyuridine-positive cells for six weeks. (11)C-PIB imaging and (18)F-FDG imaging showed the uptakes were not significantly different between between model group and transplantation group(P>0.05). CONCLUSION: (11)C-PIB imaging is useful in diagnosing AD and monitoring the pathological change of AD model in vivo, while (18)F-FDG imaging provides useful visual information for monitoring short-term therapeutic effectiveness of stem cell transplantation.

[Positron emission tomography with special tracers in pulmonary abnormalities].

OBJECTIVE: To assess the value of positron emission tomography (PET) with (11)C-choline (CH), (11)C-methionine (MET), (18)F-fluorothymidine (FLT), and (11)C-acetate (AC) in diagnosis of pulmonary abnormalities and the features of pulmonary abnormalities in PET. METHODS: From June 2002 to June 2007, 100 patients with pulmonary nodules or masses confirmed by CT scans received PET with special tracers. Fifty-eight patients received CH-PET, 16 patients received MET-PET, 22 patients received FLT-PET, 4 patients received AC-PET. PET data was analyzed by visual method and semiquantitative method with standard uptake value (SUV). Diagnoses were compared with pathology and follow-up survey. RESULTS: For identification of pulmonary neoplasms with CH-PET, the sensitivity, specificity and accuracy were 84.2% (32/38), 57.9% (11/19) and 75.4% (43/57). In cancer cases, SUV had no correlation with tumor size or age. For identification of pulmonary neoplasms with MET-PET, the sensitivity, specificity and accuracy were 6/7, 6/9 and 75.0% (12/16). In cancer cases, SUV had not correlation with tumor size or age. For identification of pulmonary neoplasms with FLT-PET, the sensitivity, specificity and accuracy were 85.7% (12/14), 2/8 and 63.6% (14/22). In cancer cases, SUV had not correlation with tumor size or age. In AC-PET, only 1 case of pulmonary metastasis of kidney clear cell carcinoma showed acetate avid. Two squamous cell carcinoma and 1 adenocarcinoma didn't appear abnormal in AC-PET. CONCLUSION: CH, MET, FLT, AC are valuable in diagnosing but also lead to false positive and false negative.

In-vivo PET imaging of implanted human retinal pigment epithelium cells in a Parkinson's disease rat model.

BACKGROUND AND AIM: Researchers find that monitoring the differentiation of implanted cells in vivo is difficult. This study was designed to show that it is possible to track the efficacy of transplanted human retinal pigment epithelial cells (RPE cells) in a rat model of Parkinson's disease by using positron emission tomography (PET). METHODS: RPE cells or normal saline were injected into striatum of the injured side of the rat model in treated and control groups, respectively. PET imaging of both groups was undertaken before transplantation and at intervals afterwards, using C-raclopride and C-beta-CFT as the markers. Observation of the rats' behaviour and immunofluorescence confocal microscopy were also used to prove the PET results. RESULTS: PET studies showed increased accumulation of C-raclopride and decreased C-beta-CFT in the injured side of striatum in both groups. C-raclopride decreased along with a concomitant increase of C-beta-CFT after transplantation in the treated group. The changes shown by the PET studies paralleled the behavioural states and confocal microscopy observations in the treated animals. CONCLUSION: These results suggest that even a clinical PET scanner could, to a certain extent, provide some information on the existence and in-vivo differentiation of RPE cells in a rat model of Parkinson's disease.

[Value of carbon-11 choline positron emission tomography in patients with pulmonary abnormalities].

OBJECTIVE: To assess the value of carbon-11 choline (CH) positron emission tomography (PET) in patients with pulmonary nodules. METHODS: From September 2002 to December 2004, 39 patients with pulmonary nodules were imaged with CH-PET. CH-PET data was analyzed by visual method and semiquantitative method. When pulmonary nodules with abnormal CH uptake appeared in PET scans confirmed by visual method, their maximum and mean standard uptake value (SUVmax and SUVmean) were measured using semiquantitative method. Diagnoses were confirmed by surgery or biopsy and follow-up survey. RESULTS: Twenty-four cancerous and 3 inflammatory nodules and 1 bronchogenic cyst were detected by CH-PET and were diagnosed malignant with visual method. Three bronchial alveolar carcinoma, 2 metastatic tumor from kidney and colon, 3 fibrous nodules, 1 cryptococcosis, 1 hamartoma and 1 sclerosing hemangioma showed nothing abnormal in PET scans. For identification of pulmonary nodules with CH-PET, the sensitivity was 89% (24/29), the specificity was 60% (6/10), and the accuracy was 77% (30/39). There were differences in SUV between 8 squamous cell carcinomas and 9 adenocarcinomas (Z = -2.937, -2.887, P < 0.01). In diagnosing 70 resected enlarged lymph nodes beyond 1 cm in 17 lung cancer patients, CH-PET had the sensitivity of 86% (25/29), the specificity of 90% (37/41), and the accuracy of 89% (62/70). CH-PET confirmed 7 distant metastases in 25 lung cancer patients. In 5 cases suspected brain metastases CH-PET identified 2 cases positive correctly. CONCLUSIONS: CH-PET can confirm malignant pulmonary nodules, but still there were false positive and false negative cases. CH-PET can evaluate N stage effectively in patients with lung cancer. CH-PET can depict brain metastases accurately.