Preclinical study and first-in-human imaging of [18F]FAP-2286, and comparison with 2-[18F]FDG PET/CT in various cancer patients.

PURPOSE: Fibroblast-activated protein (FAP) is highly expressed in cancer-associated fibroblasts (CAFs) of many solid cancers, but low or absent in normal tissues. Our study aimed to develop a novel FAP-specific tracer, namely [18F]FAP-2286, and evaluated its performance in comparison with well-established agents such as [18F]FAPI-42 and [68Ga]Ga-FAP-2286 in preclinical research, as well as 2-[18F]FDG in pilot clinical study. METHODS: [18F]FAP-2286 was manually synthesized in accordance with Good Manufacturing Practice (GMP). Subsequent investigations encompassed cell uptake, competitive binding affinity, internalization and efflux assays using HT-1080hFAP cell lines. PET imaging and biodistribution studies were conducted in HEK-293ThFAP, A549hFAP, HT-1080hFAP tumor-bearing mice as well as HEK-293T, A549 and HT-1080 control groups. Furthermore, clinical evaluation of [18F]FAP-2286 was performed in fifteen patients with various cancers compared to 2-[18F]FDG PET. RESULTS: The radiolabeling yield of [18F]FAP-2286 was 30.53 ± 5.20%, with a radiochemical purity exceeding 97%. In cell assays, [18F]FAP-2286 showed specific uptake, high internalization fraction and low cellular efflux. Rapid tumor uptake and satisfactory tumor retention was observed on micro-PET imaging and cancer patients. Meanwhile, the clinical research demonstrated that [18F]FAP-2286 may represent an alternative for low glucose-metabolism malignant tumors PET imaging such as gastric cancers. CONCLUSION: [18F]FAP-2286 showed superior imaging quality including rapid and high target uptake and satisfactory retention in both tumor-bearing mice and cancer patients. It may emerge as a promising candidate for early or delayed phase imaging and 2-[18F]FDG non-avid cancers PET scan.

Confinement effects of mandrel degradation in ICF target fabrication.

Understanding and further regulating the degradation of mandrel materials is a key aspect of target fabrication in inertial confinement fusion (ICF). Here, a quasi-one-dimensional confinement model is developed using a series of single-walled carbon nanotubes with varying diameters (Dm), and the degradation of poly-α-methylstyrene (PAMS) as a typical mandrel material is investigated under such confined conditions by using the combined method of quantum mechanics and molecular mechanics. In comparison to the isolated system, the calculations show that confinement can decrease or increase the energy barriers of PAMS degradation, which directly depends on Dm. Following which a clear exponential relationship between the degradation rate of PAMS and its own density is derived, indicating that the density of PAMS can be used to regulate mandrel degradation. This work highlights the important effects of confinement on degradation and provides a valuable reference for further development of polymer degradation technologies in ICF target fabrication and other fields.

Assessment of water enema PET/CT: an effective imaging technique for the diagnosis of incidental colorectal 18F-FDG uptake.

BACKGROUND: To validate the feasibility of water enema PET/CT (WE-PET/CT) in incidental colorectal 18F-FDG uptake and improve the accuracy of diagnosing colorectal neoplastic lesions. METHODS: We retrospectively analysed the electronic records of 338 patients undergoing common PET/CT and WE-PET/CT at our hospital. PET/CT results were correlated with colonoscopy pathology and follow-up results. The ROC contrast curve was plotted to evaluate the accuracy of SUVmax on common PET/CT and WE-PET/CT for detecting neoplastic lesions. SUVmax and the median retention indexes (RIs) of cancerous, precancerous, and benign lesions and physiologic uptake were compared. RESULTS: The sensitivity, specificity and accuracy of diagnosing neoplastic lesions with common PET/CT were 84.0%, 78.3% and 80.2%, respectively. The corresponding results with WE-PET/CT were 95.8%, 96.5% and 96.2%. The AUC of SUVmax on WE-PET/CT was significantly higher than that on common PET/CT (0.935 vs. 0.524, p < 0.001). The median SUVmax on WE-PET/CT was significantly higher than that on common PET/CT in cancerous and precancerous lesions, and significantly decreased in benign lesions and physiologic uptake (p < 0.001). The RI was significantly different between cancerous lesions and physiologic uptake, between precancerous lesions and physiologic uptake, between benign lesions and physiologic uptake, and between cancerous and benign lesions (p < 0.05). CONCLUSIONS: WE-PET/CT is a noninvasive, well-tolerated and effective technique for diagnosing incidental colorectal 18F-FDG uptake. It is helpful for a timely colonoscopy and can effectively avoid an unnecessary colonoscopy for incidental colorectal 18F-FDG uptake.

Side-chain engineering for high degradation performance of mandrel materials in ICF target fabrication.

The exploration of mandrel materials with superior degradation performance to the traditionally adopted hydrocarbon polymer of poly-α-methylstyrene (PAMS), has always been an important pursuit for fabricating high-quality inertial confinement fusion (ICF) targets. Here, we propose a method to enhance the degradation performance of mandrel material based on side-chain engineering. A series of hydrocarbon cyclic functional groups, including cyclopentane, cyclopentadiene, naphthalene and azulene, are used to replace the benzene ring on the side chain of PAMS to form new polymer structures. The results show that the degradation performance of structures can be largely regulated by different side chains. In particular, one of the naphthalene-substituted structures has similar properties to PAMS, but the required degradation condition is lower. Furthermore, the reaction rate calculations indicate that this structure is expected to be synthesized experimentally. This work provides a direction for side-chain engineering for research into the key technology of ICF target fabrication in the future.

First Inertial Confinement Fusion Implosion Experiment in Octahedral Spherical Hohlraum.

In inertial confinement approaches to fusion, the asymmetry of target implosion is a major obstacle to achieving high gain in the laboratory. A recently proposed octahedral spherical hohlraum makes it possible to naturally create spherical target irradiation without supplementary symmetry control. Before any decision is made to pursue an ignition-scale laser system based on the octahedral hohlraum, one needs to test the concept with the existing facilities. Here, we report a proof-of-concept experiment for the novel octahedral hohlraum geometry on the cylindrically configured SGIII laser facility without a symmetry control. All polar and equatorial self-emission images of the compressed target show a near round shape of convergence ratio 15 under both square and shaped laser pulses. The observed implosion performances agree well with the ideal spherical implosion simulation. It also shows limitations with using the existing facilities and adds further weight to the need to move to a spherical port geometry for future ignition laser facilities.

Heterotrimeric G-protein α subunit (LeGPA1) confers cold stress tolerance to processing tomato plants (Lycopersicon esculentum Mill).

BACKGROUND: Tomatoes (Lycopersicon esculentum Mill) are key foods, and their molecular biology and evolution have been well described. Tomato plants originated in the tropics and, thus, are cold sensitive. RESULTS: Here, we generated LeGPA1 overexpressing and RNA-interference (RNAi) transgenic tomato plants, which we then used to investigate the function of LeGPA1 in response to cold stress. Functional LeGPA1 was detected at the plasma membrane, and endogenous LeGPA1 was highly expressed in the roots and leaves. Cold treatment positively induced the expression of LeGPA1. Overexpression of LeGPA1 conferred tolerance to cold conditions and regulated the expression of genes related to the INDUCER OF CBF EXPRESSION-C-REPEAT-BINDING FACTOR (ICE-CBF) pathway in tomato plants. In the LeGPA1-overexpressing transgenic plants, the superoxide dismutase, peroxidase, and catalase activities and soluble sugar and proline contents were increased, and the production of reactive oxygen species and membrane lipid peroxidation decreased under cold stress. CONCLUSIONS: Our findings suggest that improvements in antioxidant systems can help plants cope with the oxidative damage caused by cold stress, thereby stabilizing cell membrane structures and increasing the rate of photosynthesis. The data presented here provide evidence for the key role of LeGPA1 in mediating cold signal transduction in plant cells. These findings extend our knowledge of the roles of G-proteins in plants and help to clarify the mechanisms through which growth and development are regulated in processing tomato plants.

Diagnostic performance of ultrasonography, dual-phase 99mTc-MIBI scintigraphy, early and delayed 99mTc-MIBI SPECT/CT in preoperative parathyroid gland localization in secondary hyperparathyroidism.

BACKGROUND: Secondary hyperparathyroidism (SHPT) usually requires parathyroidectomy when drug regimens fail. However, obtaining an exact preoperative map of the locations of the parathyroid glands is a challenge. The purpose of this study was to compare the diagnostic performance of US, dual-phase 99mTc-MIBI scintigraphy, early and delayed 99mTc-MIBI SPECT/CT in patients with SHPT. METHODS: Sixty patients with SHPT who were undergoing dialysis were evaluated preoperatively by US, dual-phase 99mTc-MIBI scintigraphy, early and delayed 99mTc-MIBI SPECT/CT. Postoperative pathology served as the gold standard. The sensitivity, specificity, and accuracy were determined for each method. Spearman correlation analysis was used to analyse the correlation of hyperplastic parathyroid calcification with serum alkaline phosphatase (ALP) and parathyroid hormone (PTH). RESULTS: A total of 229 lesions in 60 patients were pathologically confirmed to be parathyroid hyperplasia, with 209 lesions in typical sites, 15 lesions in the upper mediastinum and 5 lesions in the thyroid. A total of 88.33% (53/60) of patients had four lesions. US, early and delayed 99mTc-MIBI SPECT/CT had significantly higher sensitivity and accuracy than dual-phase 99mTc-MIBI scintigraphy (P < 0.001). Furthermore, early 99mTc-MIBI SPECT/CT had significantly higher sensitivity (P < 0.001) and accuracy (P = 0.001 and P < 0.001) than US and delayed 99mTc-MIBI SPECT/CT. In patients with ectopic hyperplastic parathyroid glands, the sensitivity of early 99mTc-MIBI SPECT/CT (90%) was significantly higher than that of US (55%) and dual-phase 99mTc-MIBI scintigraphy (50%) (P < 0.05). The Spearman correlation results showed a significant albeit weak association between calcification and both serum PTH and ALP (P = 0.002). CONCLUSION: The ability of early 99mTc-MIBI SPECT/CT to detect hyperplastic parathyroid glands in patients with SHPT is superior to that of US, dual-phase 99mTc-MIBI scintigraphy and delayed 99mTc-MIBI SPECT/CT; furthermore, dual-phase 99mTc-MIBI SPECT/CT is not essential.

PET Imaging of Hepatocellular Carcinomas: 18F-Fluoropropionic Acid as a Complementary Radiotracer for 18F-Fluorodeoxyglucose.

OBJECTIVE: To evaluate the preclinical value of 18F-fluoropropionic acid (18F-FPA) and 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) for imaging HCCs. METHODS: The 18F-FPA and 18F-FDG uptake patterns in 3 HCC cell lines (Hep3B, HepG2, and SK-Hep1) were assessed in vitro and in vivo. The 18F-FPA uptake mechanism was investigated using inhibition experiments with orlistat and 5-tetradecyloxy-2-furoic acid. The 18F-FPA PET imaging was performed in different tumor animal models and compared with 18F-FDG. We also evaluated the expressions of glucose transporter-1 (GLUT1), fatty acid synthase (FASN), and matrix metalloproteinase-2 (MMP2) in these cell lines. RESULTS: In vitro experiments showed that the radiotracer uptake patterns were complementary in the HCC cell lines. Orlistat and 5-tetradecyloxy-2-furoic acid decreased the uptake of 18F-FPA. The tumor-to-liver ratio of 18F-FPA was superior to that of 18F-FDG in the SK-Hep1 and HepG2 tumors ( P < .05). However, in the Hep3B tumors, the tumor-to-liver normalized uptake of 18F-FDG was higher than 18F-FPA ( P < .01). FASN was highly expressed in cell lines with high 18F-FPA uptake, whereas GLUT1 was highly expressed in cell lines with high 18F-FDG uptake. The 18F-FPA uptake correlated with FASN ( r = 0.89, P = .014) and MMP2 ( r = 0.77, P = .002) expressions. CONCLUSIONS: PET imaging with 18F-FPA combined with 18F-FDG can be an alternative for detecting HCC.

High performance optical temperature sensing via selectively partitioning Cr4+ in the residual SiO2-rich phase of glass-ceramics.

Quadrivalent Cr4+ theoretically exhibits great potential to achieve higher photo-luminescence (PL) lifetime based temperature sensitivity than the commonly utilized trivalent Cr3+, but the problem is how to stabilize the anomalous quadrivalent chemical state of Cr4+. Here we propose a type of glass-ceramic phase structure with a precipitated ZnAl2O4 crystalline sub-phase and a residual ZnO-SrO-SiO2 glassy sub-phase, where Cr4+ can be well stabilized in the residual glassy sub-phase. From PL spectra, Cr4+ or Cr3+ was found to be located at Td (tetrahedral crystal filed) or Oh (octahedral crystal filed) sites with a relatively high crystal field strength. The thermally coupled 1E(1D)/3T2(3F) states of Cr4+ or the 2E(2G)/4T2(4F) states of Cr3+ were revealed as competitive energy level pairs suitable for PL lifetime based temperature sensing. Quadrivalent Cr4+ had a particular PL lifetime ratio of 1E(1D)/3T2(3F) up to 103, which was much higher than that (101) of trivalent Cr3+:2E(2G)/4T2(4F). This supported Cr4+ to eventually achieve a higher temperature sensitivity (1.72% K-1) one order of magnitude higher than that of Cr3+ (0.83% K-1). This provides the possibility of utilizing Cr4+-doped glass to develop a type of temperature sensor with high precision and sensitivity.

An effective method to make polymers degrade readily: spatial isomerization.

The widespread application of hydrocarbon polymers has spurred an increasing interest in the study of their degradation mechanism. In general, the chemical inertness of polymers makes their degradation by low-energy processes a challenging problem. Herein, we report a method of spatial isomerization to make polymers degrade easily. The first-principles calculations show that the energy barrier required for degradation reaction is directly related to the spatial arrangement of the polymer, with the isotactic structure and most atactic structures being easier to degrade than the syndiotactic structure. Therefore, a new way to accelerate the degradation by achieving spatial isomerization of polymers has been proposed. Furthermore, the synthesis rates of these structures have also been calculated to support future experiments.

Apoptotic PET Imaging of Rat Pulmonary Fibrosis With [18F]ML-8.

OBJECTIVE: To investigate the value of 2-(3-[18F]fluoropropyl)-2-methyl-malonic acid ([18F]ML-8) positron emission tomography (PET) imaging of rat pulmonary fibrosis. METHODS: Male Sprague-Dawley rats were divided into 2 groups, including pulmonary fibrosis model group and control group. The rat model was established by an intratracheal instillation of bleomycin (BLM). Control rats were treated with saline. Positron emission tomography/computed tomography (CT) with [18F]ML-8 or 18F-fluorodeoxyglucose ([18F]FDG) was performed on 2 groups. After PET/CT imaging, lung tissues were collected for histologic examination. Data were analyzed and comparisons between 2 groups were performed using Student t test. RESULTS: Bleomycin-treated rats showed a higher lung uptake of [18F]ML-8 than control rats ( P < .05). In BLM-treated rats, the lung to muscle relative uptake ratio of [18F]ML-8 was also higher than that of [18F]FDG ( P < .05). Pathological examination showed overproliferation of fibroblasts and deposition of collagen in lungs from BLM-treated rats. Compared to control rats, BLM-treated rats had higher lung hydroxyproline content ( P < .05). Immunofluorescence staining indicated more apoptotic cells in BLM-treated rats than those in control rats. Moreover, the apoptosis rate of lung tissues obtained from BLM-treated rats was higher than that from control rats ( P < .05). CONCLUSIONS: 2-(3-[18F]fluoropropyl)-2-methyl-malonic acid PET/CT could be used for noninvasive diagnosis of pulmonary fibrosis in a rat model.

PET imaging of cardiomyocyte apoptosis in a rat myocardial infarction model.

Cardiomyocyte apoptosis has been observed in several cardiovascular diseases and contributes to the subsequent cardiac remodeling processes and progression to heart failure. Consequently, apoptosis imaging is helpful for noninvasively detecting the disease progression and providing treatment guidance. Here, we tested 18F-labeled 2-(5-fluoropentyl)-2-methyl-malonic acid (18F-ML-10) and 18F-labeled 2-(3-fluoropropyl)-2-methyl-malonic acid (18F-ML-8) for apoptosis imaging in rat models of myocardial infarction (MI) and compared them with 18F-fluorodeoxyglucose (18F-FDG). MI was induced in Sprague-Dawley rats by permanent left coronary artery ligation. Procedural success was confirmed by echocardiography and positron emission tomography (PET) imaging with 18F-FDG. In vivo PET imaging with 18F-ML-10 and 18F-ML-8 was performed in the MI models at different time points after operation. Terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assays and immunohistochemical analyses were used to evaluate myocardial apoptosis. In vitro cell binding assays were performed to validate 18F-ML-8 binding to apoptotic cardiomyocytes. PET imaging demonstrated high 18F-ML-10 and 18F-ML-8 uptake where 18F-FDG uptake was absent. The focal accumulation of the two tracers was high on days 1 and 3 but was not notable on days 5 and 7 after surgery. The infarct-to-lung uptake ratio was 4.29 ± 0.30 for 18F-ML-10 and 3.51 ± 0.18 for 18F-ML-8 (n = 6, analyzed by averaging the uptake ratios on postoperative days 1 and 3, P < 0.05). The TUNEL results showed that myocardial cell apoptosis was closely related to the focal uptake of the apoptotic tracers in the infarct area. In addition, the apoptosis rates calculated from the TUNEL results were better correlated with 18F-ML-8 uptake than with 18F-ML-10 uptake. Ex vivo cell binding assays demonstrated that 18F-ML-8 accumulated in apoptotic cells but not in necrotic or normal cells. PET imaging using 18F-ML-10 or 18F-ML-8 allows the noninvasive detection of myocardial apoptosis in the early phase. In addition, 18F-ML-8 may be better than 18F-ML-10 for apoptosis imaging. We propose that PET imaging with 18F-ML-10 or 18F-ML-8 combined with 18F-FDG is an alternative for detecting and assessing MI.

Synthesis and Ceramic Conversion of a New Organodecaborane Preceramic Polymer with High-Ceramic-Yield.

Boron carbide is one of the hardest materials known, with diamond-like mechanical properties and excellent chemical stability. It is wildly used in military defense area, nuclear industry, aerospace technology, etc. Precursor-derived ceramics have made it easier to produce pure boron carbide in processed forms and expand its applications. The challenge of this method is the synthesis of precursor polymer with high-ceramic-yield. The aim of the present work is to develop a new poly(6-norbornenyldecaborane-co-decaborane) [P(ND-co-D)] copolymer, which was successfully synthesized via ring-opening metathesis polymerization of 6-norbornenyldecaborane and tandem hydroboration with decaborane. The obtained light-yellow powder displayed good solubility, and was fully characterized by NMR, FT-IR and GPC analysis. Thermogravimetric analysis demonstrated that the char yield was up to 79%. The polymer-to-ceramic transformation process and pyrolysis mechanism has shown that the rearrangement of carbon chains of P(ND-co-D) mainly occurred in the temperature range of 350 °C~470 °C. Furthermore, the crystallization behavior and microstructures of derived ceramics were studied by XRD and SEM. Nano-sized boron carbide powders were prepared by pyrolysis of P(ND-co-D) under argon at 1400 °C for 2 h, while the structure and morphologies of the obtained rhombohedral B4C were investigated.

Elevated tumor-to-liver uptake ratio (TLR) from 18F-FDG-PET/CT predicts poor prognosis in stage IIA colorectal cancer following curative resection.

PURPOSE: The prognostic value of the tumor-to-liver uptake ratio (TLR) from 18-fluoro-2-deoxyglucose positron emission tomography/computed tomography (18F-FDG-PET/CT) in the early stage of colorectal cancer (CRC) is unclear. Notably, some stage IIA CRC patients experience early recurrence even after curative resection and might benefit from neoadjuvant or adjuvant chemotherapy. This study aims to evaluate whether elevated TLR from 18F-FDG-PET/CT can predict poor prognosis in stage IIA CRC patients undergoing curative resection. METHODS: From April 2010 to December 2013, 504 consecutive CRC patients with different TNM stages (I-IV) underwent 18F-FDG-PET/CT scans at the 6th Affiliated Hospital of Sun Yat-Sen University. Among the patients, 118 with stage IIA CRC who accepted preoperative 18F-FDG-PET/CT scanning and were treated with curative surgery alone were reviewed retrospectively. The maximum standardized uptake value (SUVmax) in the primary tumor, TLR, and demographic, clinical, histopathological, and laboratory data were analyzed. Receiver operating characteristic (ROC) curve, univariate and multivariate analyses were performed to identify prognostic factors associated with patient disease-free survival (DFS) and overall survival (OS). RESULTS: ROC curve analysis demonstrated that TLR was superior to primary tumor SUVmax in predicting the risk of recurrence in stage IIA CRC. The optimal TLR cutoff was 6.2. Univariate analysis indicated that elevated TLR, tumor size, and lymphovascular/neural invasion correlated with DFS (P = 0.001, P = 0.002, and P = 0.001, respectively) and OS (P = 0.001, P = 0.003, and P < 0.001, respectively). The 1-, 3-, and 5-year DFS rates were 98.4%, 96.9%, and 96.9% for stage IIA CRC patients with lower TLR (≤6.2) versus 77.8%, 60.6%, and 60.6% for those with elevated TLR (>6.2), respectively. The 1-, 3-, and 5-year OS rates were 100.0%, 100.0%, and 98.3% for the patients with lower TLR versus 98.1%, 83.3%, and 74.3% for those with elevated TLR. Cox regression analysis showed that elevated TLR [>6.2; hazard ratio (HR): 3.109-57.463; P < 0.001] and tumor size (>4.4 cm; HR: 1.636-19.155; P = 0.006) were independent risk factors for DFS. Meanwhile, elevated TLR (>6.2; HR: 1.398-84.945; P = 0.023) and lymphovascular/neural invasion (positive; HR: 1.278-12.777; P = 0.017) were independent risk factors for OS. CONCLUSION: Elevated TLR predicted worse DFS and OS for stage IIA CRC patients and might serve as a potential radiological index to identify candidates for neoadjuvant or adjuvant chemotherapy. Stage IIA CRC patients with elevated TLR should be monitored carefully for early detection of possible recurrence.

Automated synthesis of N-(2-[18 F]Fluoropropionyl)-l-glutamic acid as an amino acid tracer for tumor imaging on a modified [18 F]FDG synthesis module.

N-(2-[18 F]Fluoropropionyl)-l-glutamic acid ([18 F]FPGLU) is a potential amino acid tracer for tumor imaging with positron emission tomography. However, due to the complicated multistep synthesis, the routine production of [18 F]FPGLU presents many challenging laboratory requirements. To simplify the synthesis process of this interesting radiopharmaceutical, an efficient automated synthesis of [18 F]FPGLU was performed on a modified commercial fluorodeoxyglucose synthesizer via a 2-step on-column hydrolysis procedure, including 18 F-fluorination and on-column hydrolysis reaction. [18 F]FPGLU was synthesized in 12 ± 2% (n = 10, uncorrected) radiochemical yield based on [18 F]fluoride using the tosylated precursor 2. The radiochemical purity was ≥98%, and the overall synthesis time was 35 minutes. To further optimize the radiosynthesis conditions of [18 F]FPGLU, a brominated precursor 3 was also used for the preparation of [18 F]FPGLU, and the improved radiochemical yield was up to 20 ± 3% (n = 10, uncorrected) in 35 minutes. Moreover, all these results were achieved using the similar on-column hydrolysis procedure on the modified fluorodeoxyglucose synthesis module.

Depolymerization of Free-Radical Polymers with Spin Migrations.

The mechanism of depolymerization is one of the most essential issues in chemical engineering and materials science. In this work, we investigate the depolymerization reactions of three typical free-radical poly(alpha-methylstyrene) tetramers by using first-principles density functional theory. The calculated results show that these reactions all need to overcome the energy barriers in the range of 0.58 to 0.77 eV, and that breaking the C-C bond at the chain end leads to the dissociation of alpha-methylstyrene monomers from the polymers. Electronic-structure analysis indicates that the reactions occur easily at the CR3 unsaturated end, and that the frontier molecular orbitals that participate in the reactions are mainly localized at the unsaturated ends. Meanwhile, spin population analysis presents the unique net spin-transfer process in free-radical depolymerization reactions. We hope the current findings can contribute to understanding the free-radical depolymerization mechanism and help guide future experiments.

Case report: Uncommon multiple metastases from occult breast cancer revealed by 68Ga-DOTATATE PET/CT.

Occult breast cancer is an uncommon type of breast cancer and its diagnosis is challenging. It is usually invisible on multiple imaging examines. Metastases to the rectum and inguinal lymph nodes from occult breast lobular cancer are even rarer. 68Ga-DOTA peptides can image neuroendocrine tumors by targeting specific somatostatin receptors. Besides, other tumors, including breast cancer, have been shown to express somatostatin receptors. In this case, we presented a 63-year-old woman who underwent both 18F-FDG and 68Ga-DOTATATE PET/CT due to a rectal polyp. An endoscopic excision biopsy confirmed metastatic carcinoma of suspected breast origin, but subsequent ultrasound and MRI showed no signs of malignancy in the breast and adnexa uteri. PET/CT showed obvious 68Ga-DOTATATE activity in bilateral axillary and right inguinal lymph nodes with mild 18F-FDG uptake. Final histopathology at the left axillary, right inguinal lymph nodes, and rectum indicated metastases from breast cancer while the origin remained radiologically occult. Additionally, one uterine fibroids was found with positive uptake of 68Ga-DOTATATE and negative uptake of 18F-FDG. This case suggested that 68Ga-DOTATAE PET/CT may be an effective supplement in diagnosing OBC lymph node metastases with mild 18F-FDG uptake, and it may provide a new technology for the clinical diagnosis of occult breast cancer.

Initiator enhancement of mandrel degradation for ICF target fabrication.

Poly-α-methylstyrene (PAMS), as an ideal mandrel material used in the fabrication of inertial confinement fusion (ICF) targets, its efficient degradation is the key to the quality of targets. However, there is a great challenge to achieve enhanced degradation. Here, we proposed the strategy to optimize the degradation of PAMS microspheres using di-tert-butyl peroxide (DTBP) as a degradation initiator. Experimentally, monodisperse PAMS microspheres with DTBP were controllably prepared by a microfluidic-based microencapsulation technique. Thermogravimetric results show that DTBP largely decreases the initial degradation temperature from 550 K to 450 K, which effectively promotes the thermal degradation of PAMS microspheres. Theoretically, DTBP can reduce the activation energy of degradation. Moreover, the potential energy surfaces were used to describe the degradation process at the atomic level. Our work brings a new direction for the study of mandrel degradation in ICF targets fabrication, and also provides a valuable reference for solving the pollution of waste plastics.

Quantum tunneling of hydrogen atom transfer affects mandrel degradation in inertial confinement fusion target fabrication.

Poly-α-methylstyrene (PAMS) is considered as the preferred mandrel material, whose degradation is crucial for the fabrication of high-quality inertial confinement fusion (ICF) targets. Herein, we reveal that hydrogen atom transfer (HAT) during PAMS degradation, which is usually attributed to the thermal effect, unexpectedly exhibits a strong high-temperature tunneling effect. Specifically, although the energy barrier of the HAT reaction is only 10-2 magnitude different from depolymerization, the tunneling probability of the former can be 14-32 orders of magnitude greater than that of the latter. Furthermore, chain scission following HAT will lead to a variety of products other than monomers. Our work highlights that quantum tunneling may be an important source of uncertainty in PAMS degradation, which will provide a direction for the further development of key technology of target fabricating in ICF research and even the solution of plastic pollution.

Propionic Acid-Based PET Imaging of Prostate Cancer.

PURPOSE: This study aimed to evaluate the potential value of 2-[18F]fluoropropionic acid ([18F]FPA) for PET imaging of prostate cancer (PCa) and to explore the relationship between [18F]FPA accumulation and fatty acid synthase (FASN) levels in PCa models. The results of the first [18F]FPA PET study of a PCa patient are reported. PROCEDURES: The LNCaP, PC-3 cell lines with high FASN expression, and DU145 cell lines with low FASN expression were selected for cell culture. A PET imaging comparison of [18F]FDG and [18F]FPA was performed in LNCaP, PC-3, and DU145 tumors. Additionally, in vivo inhibition experiments in those models were conducted with orlistat. In a human PET study, a patient with PCa before surgery was examined with [18F]FPA PET and [18F]FDG PET. RESULTS: The uptake of [18F]FPA in the LNCaP and PC-3 tumors was higher than that of [18F]FDG (P<0.05 and P<0.05), but was lower in DU145 tumors (P<0.05). The accumulation (% ID/g) of [18F]FPA in the LNCaP, PC-3, and DU145 tumors decreased by 27.6, 40.5, and 11.7 %, respectively, after treatment with orlistat. The [18F]FPA showed higher radioactive uptake than [18F]FDG in the first PCa patient. CONCLUSIONS: The [18F]FPA uptake in PCa models may be varies with fatty acid synthase activity and could be reduced after administration of a single FASN inhibitor, albeit the activity that is not measured directly. The [18F]FPA seems to be a potential broad-spectrum PET imaging agent and may serve as a valuable tool in the diagnosis of PCa in humans.