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Objective This study aimed to compare [ 68 Ga]Ga-FAPI-04/[ 18 F]FAPI-42 PET/CT with [ 18 F]FDG PET/CT in the evaluation of initial gastric cancer. Methods We retrospectively compared [ 68 Ga]Ga-FAPI-04/[ 18 F]FAPI-42 PET/CT with [ 18 F]FDG PET/CT in patients with initial gastric cancer from September 2020 to March 2021. Lesion detectability and the uptake of lesions quantified by the maximum standardized uptake value (SUVmax) and target-to-background ratio (TBR) were compared between the two modalities using the Wilcoxon signed-rank test, Mann–Whitney U test, and McNemar’s chi-square test. Results A total of 61 patients (37 males, aged 23–81 years) were included, of which 22 underwent radical gastrectomy. For primary lesions, higher uptake of [ 68 Ga]Ga-FAPI-04/[ 18 F]FAPI-42 was observed compared to [ 18 F]FDG (median SUVmax, 14.60 vs 4.35, p < 0.001), resulting in higher positive detection using [ 68 Ga]Ga-FAPI-04/[ 18 F]FAPI-42 PET/CT than [ 18 F]FDG PET/CT (95.1% vs 73.8%, p < 0.001), particularly for tumors with signet-ring cell carcinoma (SRCC) (96.4% vs 57.1%, p < 0.001). [ 68 Ga]Ga-FAPI-04/[ 18 F]FAPI-42 PET/CT detected more positive lymph nodes than [ 18 F]FDG PET/CT (637 vs 407). However, both modalities underestimated N staging compared to pathological N staging. [ 68 Ga]Ga-FAPI-04/[ 18 F]FAPI-42 PET/CT showed a higher sensitivity (92.3% vs 53.8%, p = 0.002) and peritoneal cancer index score (18 vs 3, p < 0.001) in peritoneum metastasis and other suspect metastases compared to [ 18 F]FDG PET/CT. Conclusion Our findings indicate that [ 68 Ga]Ga-FAPI-04/[ 18 F]FAPI-42 PET/CT outperformed [ 18 F]FDG PET/CT in the evaluation of primary tumors with SRCC and peritoneum metastasis in initial gastric cancer. However, no clinically useful improvement was seen in N staging. Key Points • The uptake of [ 68 Ga]Ga-FAPI-04/[ 18 F]FAPI-42 in primary tumor and metastasis was intensely higher than that of [ 18 F]FDG (p < 0.001) in 61 patients with initial gastric cancer . • [ 68 Ga]Ga-FAPI-04/[ 18 F]FAPI-42 PET/CT had a higher sensitivity detection in primary tumors (95.1% vs 73.8%, p < 0.001) and peritoneal metastases (92.3% vs 53.8%, p = 0.002) than [ 18 F]FDG PET/CT . • [ 68 Ga]Ga-FAPI-04/[ 18 F]FAPI-42 PET/CT depicted more positive lymph nodes than [ 18 F]FDG PET/CT (637 vs 407); however, both underestimated N staging compared to pathological N staging .

Background Total Body PET/CT is increasingly used in clinical practice, but its benefits for lung cancer staging are not fully established. This study aimed to evaluate the impact of Total Body PET/CT on lung cancer staging compared to traditional Whole-Body PET/CT. Results Among the 763 patients, 289 (37.9%) had stage IV disease, with 96 (33.2%) showing limb metastases, including those in the lower limbs (legs) or also the upper limbs (arms). Compared to Whole-Body PET/CT, Total Body PET/CT detected additional metastases in 60.4% (58/96) of patients with limb metastases, representing 20.1% (58/289) of all stage IV patients. These included 96 bone and 43 muscle metastases. In patients with isolated limb metastases ( n  = 31), Total Body PET/CT detected additional metastases in 13 (41.9%) compared to Whole-Body PET/CT, altering tumor staging in only one patient (0.3% of stage IV patients). In those with multiple limb metastases ( n  = 65), Total Body PET/CT detected additional metastases in 45 (69.2%), but staging remained unchanged. Distal limb metastasis was strongly associated with concurrent bone (OR = 8.288, 95%CI: 3.642–18.861) and muscle metastases outside the limb (OR = 3.911, 95%CI: 1.624–9.417) (both P  < 0.001). Additionally, Total Body PET/CT detected acute arthritis in 193 (25.3%) patients and benign lesions (e.g., varicose veins, neurogenic tumors, lipomas, fractures) in 68 (8.9%) compared to Whole-Body PET/CT. Conclusion Whole-Body imaging is sufficient to meet the clinical staging requirements for lung cancer. Although Total Body PET/CT detects more distal metastases in approximately 20% of stage IV lung cancer patients, it led to stage shift in only one patient and 0% change in the oncologic treatment.

Picoeukaryotes are a taxonomically diverse group of organisms less than 2 micrometers in diameter. Photosynthetic marine picoeukaryotes in the genus Micromonas thrive in ecosystems ranging from tropical to polar and could serve as sentinel organisms for biogeochemical fluxes of modern oceans during climate change. These broadly distributed primary producers belong to an anciently diverged sister clade to land plants. Although Micromonas isolates have high 18S ribosomal RNA gene identity, we found that genomes from two isolates shared only 90% of their predicted genes. Their independent evolutionary paths were emphasized by distinct riboswitch arrangements as well as the discovery of intronic repeat elements in one isolate, and in metagenomic data, but not in other genomes. Divergence appears to have been facilitated by selection and acquisition processes that actively shape the repertoire of genes that are mutually exclusive between the two isolates differently than the core genes. Analyses of the Micromonas genomes offer valuable insights into ecological differentiation and the dynamic nature of early plant evolution.

The smallest known eukaryotes, at ≈1-μm diameter, are Ostreococcus tauri and related species of marine phytoplankton. The genome of Ostreococcus lucimarinus has been completed and compared with that of O. tauri. This comparison reveals surprising differences across orthologous chromosomes in the two species from highly syntenic chromosomes in most cases to chromosomes with almost no similarity. Species divergence in these phytoplankton is occurring through multiple mechanisms acting differently on different chromosomes and likely including acquisition of new genes through horizontal gene transfer. We speculate that this latter process may be involved in altering the cell-surface characteristics of each species. In addition, the genome of O. lucimarinus provides insights into the unique metal metabolism of these organisms, which are predicted to have a large number of selenocysteine-containing proteins. Selenoenzymes are more catalytically active than similar enzymes lacking selenium, and thus the cell may require less of that protein. As reported here, selenoenzymes, novel fusion proteins, and loss of some major protein families including ones associated with chromatin are likely important adaptations for achieving a small cell size.

Purpose Lung tumors, which receive dual-blood-supply from the pulmonary and bronchial arteries, may exhibit distinct kinetic parameters compared to other malignancies. This study aimed to investigate the impact of various factors on the kinetic parameter quantification of [ 18 F]F-FAPI-42 dynamic PET/CT and to establish an acceptable shortened acquisition time for lung cancer. Methods A total of 19 patients with lung tumors underwent 60-minute total-body dynamic [ 18 F]F-FAPI-42 PET/CT imaging. Tumor kinetic metrics (K 1 to K 3 and K i ) were calculated using a two-tissue irreversible comparative (2TiC) model. The effects of different image-derived input function (IDIF) models (derived from the right ventricle [RV], left ventricle [LV], and descending aorta [DA]), as well as tumor location, pathohistological subtype and size on kinetic parameters were evaluated. Additionally, the mean standardized uptake value (SUV mean ), tumor-to-background ratio (TBR), signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were assessed to determine an acceptable shortened acquisition time. Results The time-activity curve (TAC) of the RV exhibited the earliest and highest peak, followed by those of the LV and DA. Impact of IDIF model and tumor size on kinetic parameters of primary tumors was observed. Specifically, in the RVIF model, size of tumor > 3 cm exhibited higher K 2 and K 3 than those with size ≤ 3 cm ( P  < 0.05). Similar findings were also noted for K 3 in the LVIF model ( P  < 0.05), but not in the DAIF model. Tumor location and pathohistological subtype had no significant impact on kinetic parameters quantification. Regarding acquisition time, the RVIF model achieved kinetic parameters equivalent to those at 60 min in 26 min, while the LVIF and DAIF models required 36 min. At 26 min, the tumors were clearly visualized, with SUV mean , SNR, CNR and TBR being equivalent or nearly approaching the values observed at 60 min. Conclusion The RVIF model appears to be more suitable than the DAIF model for quantifying kinetic parameters in [ 18 F]F-FAPI-42 PET dynamic imaging of lung cancer, with an acceptable shortened acquisition time of 26 min.

BackgroundConventional clinical PET scanners typically have an axial field of view (AFOV) of 15–30 cm, resulting in limited coverage and relatively low photon detection efficiency. Taking advantage of the development of long-axial PET/CT, the uEXPLORER PET/CT scanner with an axial coverage of 194 cm increases the effective count rate by approximately 40 times compared to that of conventional PET scanners. Ordered subset expectation maximization (OSEM) is the most widely used iterative algorithm in PET. The major drawback of OSEM is that the iteration process must be stopped before convergence to avoid image degradation due to excessive noise. A new Bayesian penalized-likelihood iterative PET reconstruction, named HYPER iterative, was developed and is now available on the uEXPLORER total-body PET/CT, which incorporates a noise control component by using a penalty function in each iteration and finds the maximum likelihood solution through repeated iterations. To date, its impact on lesion visibility in patients with a full injected dose or half injected dose is unclear. The goal of this study was to determine a proper protocol for routine 18F-FDG uEXPLORER total-body PET/CT scans.ResultsThe uEXPLORER total-body PET/CT images reconstructed using both OSEM and HYPER iterative algorithms of 20 tumour patients were retrospectively reviewed. The quality of the 5 min PET image was excellent (score 5) for all of the dose and reconstruction methods. Using the HYPER iterative method, the PET images reached excellent quality at 1 min with full-dose PET and at 2 min with half-dose PET. The PET image reached a similar excellent quality at 2 min with a full dose and at 3 min with a half dose using OSEM. The noise in the OSEM reconstruction was higher than that in the HYPER iterative. Compared to OSEM, the HYPER iterative had a slightly higher SUVmax and TBR of the lesions for large positive lesions (≥ 2 cm) (SUVmax: up to 9.03% higher in full dose and up to 12.52% higher in half dose; TBR: up to 8.69% higher in full dose and up to 23.39% higher in half dose). For small positive lesions (≤ 10 mm), the HYPER iterative had an obviously higher SUVmax and TBR of the lesions (SUVmax: up to 45.21% higher in full dose and up to 74.96% higher in half dose; TBR: up to 44.91% higher in full dose and up to 93.73% higher in half dose).ConclusionsA 1 min scan with a full dose and a 2 min scan with a half dose are optimal for clinical diagnosis using the HYPER iterative and 2 min and 3 min for OSEM. For quantification of the small lesions, HYPER iterative reconstruction is preferred.

A finite element method is presented to optimize Prager structures using a truss-like material model. The members are assumed to be distributed over the design domain continuously but non-uniformly, and their densities and orientations at nodes are taken as design variables. The initial loads are applied to the design domain uniformly, and the densities of members are optimized by fully stressed criteria, with the members aligning along the principal direction of stress. Concomitantly, loads are moved to the elevations of the centroid along the vertical direction. Through iterating the above procedure until convergence, Prager structures can be optimized into anisotropic structures in which most of the arches are not parallel to each other.

This paper considers robust fault-detection problems for linear discrete time systems. It is shown that the optimal robust detection filters for several well-recognized robust fault-detection problems, such as ℋ−/ℋ∞, ℋ2/ℋ∞, and ℋ∞/ℋ∞ problems, are the same and can be obtained by solving a standard algebraic Riccati equatio n. Optimal filters are also derived for many other optimization criteria and it is shown that some well-studied and seeming-sensible optimization criteria for fault-detection filter design could lead to (optimal) but useless fault-detection filters.

A method to maximize the natural frequencies of vibration of truss-like continua with the constraint of material volume is presented. Truss-like is a kind of particular anisotropic continuum, in which there are finite numbers of members with infinitesimal spaces. Structures are analyzed by finite element method. The densities and orientations of members at nodes are taken as design variables. The densities and orientations of members in elements are interpolated by these values at nodes; therefore they vary continuously in design domain. For no intermediate densities being suppressed, there is no numerical instability, such as checkerboard patterns and one-node connected hinges. The natural frequency and its sensitivities of truss-like continuum are derived. Optimization is achieved by the techniques of moving asymptotes and steepest descent. Several numerical examples are provided to demonstrate this optimization method.