Stable gadolinium chelates are widely used as the contrast agents (CAs) for magnetic resonance imaging (MRI). Conjugation of the chelates onto macromolecular carriers forms macromolecular CAs (mCAs). ...Compared with small molecule MRI CAs, mCAs have advantages of high relaxivity and prolonged retention in blood circulation. Variants of mCAs have been synthesized and tested using animal models, showing their great potential applications in angiography, cancer imaging, kidney imaging, liver imaging, lymphatic imaging, and noninvasive visualization of drug delivery. Herein, the state of the art of mCAs, including their structures, properties, and applications is reviewed and future directions for developing mCAs are suggested.
Thermoelectric generators (TEGs) provide a unique solution for energy harvesting from waste heat, presenting a potential solution for green energy. However, traditional rigid and flexible TEGs cannot ...work on complex and dynamic surfaces. Here, we report a stretchable TEG (S-TEG) (over 50% stretchability of the entire device) that is geometrically suitable for various complex and dynamic surfaces of heat sources. The S-TEG consists of hot-pressed nanolayered p-(Sb
Te
) and n-(Bi
Te
)-type thermoelectric couple arrays and exploits the wavy serpentine interconnects to integrate all units. The internal resistance of a 10 × 10 array is 22 ohm, and the output power is ∼0.15 mW/cm
at Δ
= 19 K on both developable and nondevelopable surfaces, which are much improved compared with those of existing S-TEGs. The energy harvesting of S-TEG from the dynamic surfaces of the human skin offers a potential energy solution for the wearable devices for health monitoring.
•Over 1000 radiomic features of coronary plaques provided more quantitative information than that provided by conventional analysis.•The radiomics model outperformed the conventional method ...assessment in the prediction of hemodynamically significant stenosis.•Radiomic feature analysis of coronary plaques provides a noninvasive approach to identify the ischemic coronary stenosis.
This study aimed to investigate the diagnostic performance of radiomics features derived from coronary computed tomography angiography (CCTA) in the identification of ischemic coronary stenosis plaque using invasive fractional flow reserve (FFR) as the reference standard.
174 plaques of 149 patients (age: 62.21 ± 8.47 years, 96 males) with at least one lesion stenosis degree between 30 % and 90 % were retrospectively included. Stenosis degree and plaque characteristics were recorded, and a conventional multivariate logistic model was established. Over 1000 radiomics features of the plaque were derived from CCTA images. The plaques were randomly divided into training set (n = 139) and validation set (n = 35). A random forest model was built. The area under the curve (AUC) of the models was compared.
Fifty-eight radiomics features were correlated with functionally significant stenosis (p < 0.05), wherein 56 features had an AUC of >0.6. NCP volume, NRS, remodeling index, and spotty calcification were included in the conventional model. Ultimately, 14 features were integrated to build the radiomics model. The AUC showed an improvement: 0.71 vs 0.82 for the training set and 0.70 vs 0.77 for the validation set (conventional model and radiomics model, respectively); however, it was not statistically significant (p = 0.58).
The radiomics analysis of plaques showed improvement compared with conventional plaques assessment in identifying hemodynamically significant coronary stenosis. The statistical advancement of machine learning for plaques to predict hemodynamic stenosis with a noninvasive approach still needs further studies on a large-scale dataset.
Continuous monitoring of the central-blood-pressure waveform from deeply embedded vessels, such as the carotid artery and jugular vein, has clinical value for the prediction of all-cause ...cardiovascular mortality. However, existing non-invasive approaches, including photoplethysmography and tonometry, only enable access to the superficial peripheral vasculature. Although current ultrasonic technologies allow non-invasive deep-tissue observation, unstable coupling with the tissue surface resulting from the bulkiness and rigidity of conventional ultrasound probes introduces usability constraints. Here, we describe the design and operation of an ultrasonic device that is conformal to the skin and capable of capturing blood-pressure waveforms at deeply embedded arterial and venous sites. The wearable device is ultrathin (240 μm) and stretchable (with strains up to 60%), and enables the non-invasive, continuous and accurate monitoring of cardiovascular events from multiple body locations, which should facilitate its use in a variety of clinical environments.
Purpose
Liver tumor segmentation is a crucial prerequisite for computer‐aided diagnosis of liver tumors. In the clinical diagnosis of liver tumors, radiologists usually examine multiphase CT images ...as these images provide abundant and complementary information of tumors. However, most known automatic segmentation methods extract tumor features from CT images merely of a single phase, in which valuable multiphase information is ignored. Therefore, it is highly demanded to develop a method effectively incorporating multiphase information for automatic and accurate liver tumor segmentation.
Methods
In this paper, we propose a phase attention residual network (PA‐ResSeg) to model multiphase features for accurate liver tumor segmentation. A phase attention (PA) is newly proposed to additionally exploit the images of arterial (ART) phase to facilitate the segmentation of portal venous (PV) phase. The PA block consists of an intraphase attention (intra‐PA) module and an interphase attention (inter‐PA) module to capture channel‐wise self‐dependencies and cross‐phase interdependencies, respectively. Thus, it enables the network to learn more representative multiphase features by refining the PV features according to the channel dependencies and recalibrating the ART features based on the learned interdependencies between phases. We propose a PA‐based multiscale fusion (MSF) architecture to embed the PA blocks in the network at multiple levels along the encoding path to fuse multiscale features from multiphase images. Moreover, a 3D boundary‐enhanced loss (BE‐loss) is proposed for training to make the network more sensitive to boundaries.
Results
To evaluate the performance of our proposed PA‐ResSeg, we conducted experiments on a multiphase CT dataset of focal liver lesions (MPCT‐FLLs). Experimental results show the effectiveness of the proposed method by achieving a dice per case (DPC) of 0.7787, a dice global (DG) of 0.8682, a volumetric overlap error (VOE) of 0.3328, and a relative volume difference (RVD) of 0.0443 on the MPCT‐FLLs. Furthermore, to validate the effectiveness and robustness of PA‐ResSeg, we conducted extra experiments on another multiphase liver tumor dataset and obtained a DPC of 0.8290, a DG of 0.9132, a VOE of 0.2637, and a RVD of 0.0163. The proposed method shows its robustness and generalization capability in different datasets and different backbones.
Conclusions
The study demonstrates that our method can effectively model information from multiphase CT images to segment liver tumors and outperforms other state‐of‐the‐art methods. The PA‐based MSF method can learn more representative multiphase features at multiple scales and thereby improve the segmentation performance. Besides, the proposed 3D BE‐loss is conducive to tumor boundary segmentation by enforcing the network focus on boundary regions and marginal slices. Experimental results evaluated by quantitative metrics demonstrate the superiority of our PA‐ResSeg over the best‐known methods.
Analysis of armature reaction field and inductance is extremely important for design and control implementation of electromagnetic machines. So far, most studies have focused on magnetic field ...generated by permanent-magnet (PM) poles, whereas less work has been done on armature reaction field. This paper proposes a novel analytical modeling method to predict the armature reaction field of a coreless PM tubular linear machine with dual Halbach array. Unlike conventional modeling approach, the proposed method formulates the armature reaction field for electromagnetic machines with finite length, so that the analytical modeling precision can be improved. In addition, winding inductance is also analytically formulated to facilitate dynamic motion control based on the reaction field solutions. Numerical result is subsequently obtained with finite-element method and employed to validate the derived analytical models. A research prototype with dual Halbach array and single phase input is developed. Experiments are conducted on the reaction field and inductance to further verify the obtained mathematical models.
Gastric bronchogenic cyst in a young woman Lou, Feifei; Chen, Qingqing; Hu, Hongjie
Asian journal of surgery,
October 2022, 2022-10-00, 2022-10-01, Letnik:
45, Številka:
10
Journal Article
Abstract Sodium taurocholate cotransporting polypeptide (NTCP) is the functional receptor for human hepatitis B virus (HBV) and its satellite hepatitis D virus (HDV). Species barriers to HBV/HDV ...infection are mainly determined at entry level by variations in the sequences of particular NTCP orthologs. In this study, we sought to determine whether the NTCP ortholog in woodchuck ( Marmota monax ), woodchuck NTCP (wNTCP) supports viral infection. We found that wNTCP is capable of supporting HBV/HDV infection in HepG2 cells, but to much lower extent than human NTCP (hNTCP), which is about 90% reduction of hNTCP. Comprehensive site-directed mutagenesis mapping of hNTCP and wNTCP revealed that the residue at position 263 is a novel site crucial for viral entry. The important role of site 263 in infection is conserved among NTCP orthologs and may therefore be a potential target for blocking the viral entry.
In this paper, a total variation (TV) minimization strategy is proposed to overcome the problem of sparse spatial resolution and large amounts of noise in low dose positron emission tomography (PET) ...imaging reconstruction. Two types of objective function were established based on two statistical models of measured PET data, least-square (LS) TV for the Gaussian distribution and Poisson-TV for the Poisson distribution. To efficiently obtain high quality reconstructed images, the alternating direction method (ADM) is used to solve these objective functions. As compared with the iterative shrinkage/thresholding (IST) based algorithms, the proposed ADM can make full use of the TV constraint and its convergence rate is faster. The performance of the proposed approach is validated through comparisons with the expectation-maximization (EM) method using synthetic and experimental biological data. In the comparisons, the results of both LS-TV and Poisson-TV are taken into consideration to find which models are more suitable for PET imaging, in particular low-dose PET. To evaluate the results quantitatively, we computed bias, variance, and the contrast recovery coefficient (CRC) and drew profiles of the reconstructed images produced by the different methods. The results show that both Poisson-TV and LS-TV can provide a high visual quality at a low dose level. The bias and variance of the proposed LS-TV and Poisson-TV methods are 20% to 74% less at all counting levels than those of the EM method. Poisson-TV gives the best performance in terms of high-accuracy reconstruction with the lowest bias and variance as compared to the ground truth (14.3% less bias and 21.9% less variance). In contrast, LS-TV gives the best performance in terms of the high contrast of the reconstruction with the highest CRC.
Cerebral glucose metabolism is a reliable index of neural activity and may provide evidence for brain function in healthy adults. We studied the correlation between cerebral glucose metabolism and ...age under the resting-state in both sexes with position emission tomography. Statistical test of age effect on cerebral glucose metabolism was performed using the statistical parametric mapping software with a voxel-by-voxel approach (p=0.05 family wise error corrected, 100-voxel threshold). The subjects consisted of 108 females (mean ± S.D. = 45 ± 10 years) and 126 males (mean ± S.D. = 49 ± 11 years). We showed here that brain activity in the frontal and temporal lobes in both sexes decreased significantly with normal aging. The glucose metabolism in the caudate bilaterally showed a negative correlation with age in males, but not in females. Few regions in males were shown with an increased glucose metabolism with age. Although the mechanisms of brain aging are still unknown, a map of brain areas susceptible to age was described in this report.
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