摘要 :
Lewis hunting reaction refers to the alternating cold-induced vasoconstriction and dilation in extremities, whose underlying mechanism is complex. While numerous studies reported this intriguing phenomenon by measuring cutaneous t...
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Lewis hunting reaction refers to the alternating cold-induced vasoconstriction and dilation in extremities, whose underlying mechanism is complex. While numerous studies reported this intriguing phenomenon by measuring cutaneous temperature fluctuation under cold exposure, few of them tracked peripheral vascular responses in real-time, lacking a non-invasive and quantitative imaging tool. To better monitor hunting reaction and diagnose relevant diseases, we developed a hybrid photoacoustic ultrasound (PAUS) tomography system to monitor finger vessels’ dynamic response to cold, together with simultaneous temperature measurement. We also came out a standard workflow for image analysis with self-defined indices. In the small cohort observational study, vascular changes in the first cycle of hunting reaction were successfully captured by the image series and quantified. Time difference between vasodilation and temperature recovery was noticed and reported for the first time, thanks to the unique capability of the PAUS imaging system in real-time and continuous vascular monitoring. The developed imaging system and indices enabled more objective and quantitative monitoring of peripheral vascular activities, indicating its great potential in numerous clinical applications.
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摘要 :Objective : Nanotheranostic systems integrate therapeutic and diagnostic procedures using nanotechnology. This type of approach has enabled the development of methods for early detection and treatment of different pathologies. Mag...
展开Objective : Nanotheranostic systems integrate therapeutic and diagnostic procedures using nanotechnology. This type of approach has enabled the development of methods for early detection and treatment of different pathologies. Magnetic hyperthermia (MH) has been proposed as an alternative or complementary method of cancer therapy. However, challenges such as delivering and localizing the magnetic nanoparticles (MNPs) within tissues and monitoring the temperature during the treatment hinder this technique to be effectively translated into a clinical routine. Therefore, in this study a theranostic platform has been proposed and examined to address two main issues, localizing MNPs and real-time temperature monitoring, for preclinical MH. Methods : The system integrates magnetomotive (MMUS) and thermal ultrasound imaging with MH. An ultrasound device was used to acquire MMUS images to detect MNPs, and ultrasound thermometry to monitor the temperature. This platform was designed such that a single coil generated the magnetic field for MMUS and MH. The feasibility of the system was examined using a tissue mimicking phantom containing an inclusion filled with zinc substituted magnetite NPs. Results : These MNPs were effectively used as contrast agent for MMUS and to generate heat during MH. In addition to localizing MNPs, real-time two-dimensional temperature maps were obtained with substantial concordance ( ρc > 0.97) with invasive measurements using fiber optic thermometer. The heating rate was proportional to the displacements in MMUS ( r = 0.92). Conclusion : Ultrasound thermometry was successfully used to monitor the temperature during MH. In addition, it was shown that acquiring MMUS images prior to MH can qualitatively predict the temperature distribution of the MNP-laden regions.
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Focused ultrasound (FUS) peripheral neuromodulation has been linked to nerve displacement caused by the acoustic radiation force; however, the roles of cavitation and temperature accumulation on nerve modulation are less clear, as...
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Focused ultrasound (FUS) peripheral neuromodulation has been linked to nerve displacement caused by the acoustic radiation force; however, the roles of cavitation and temperature accumulation on nerve modulation are less clear, as are the relationships between these three mechanisms of action. Temperature directly changes tissue stiffness and viscosity. Viscoelastic properties have been shown to affect cavitation thresholds in both theoretical and ex vivo models, but the direct effect of temperature on cavitation has not been investigated in vivo. Here, cavitation and tissue displacement were simultaneously mapped in response to baseline tissue temperatures of either 30 °C or 38 °C during sciatic nerve sonication in mice. In each mouse, the sciatic nerve was repeatedly sonicated at 1.1-MHz, 4-MPa peak-negative pressure, 5-ms pulse duration, and either 15- or 30-Hz pulse repetition frequency (PRF) for 10 s at each tissue temperature. Cavitation increased by 1.8–4.5 dB at a tissue temperature of 38 °C compared to 30 °C, as measured both by passive cavitation images and cavitation doses. Tissue displacement also increased by 1.3–
$1.8 \mu \text{m}$
at baseline temperatures of 38 °C compared to 30 °C. Histological findings indicated small increases in red blood cell extravasation in the 38 °C baseline temperature condition compared to 30 °C at both PRFs. A strong positive correlation was found between the inertial cavitation dose and displacement imaging noise, indicating the potential ability of displacement imaging to simultaneously detect inertial cavitation in vivo. Overall, tissue temperature was found to modulate both in vivo cavitation and tissue displacement, and thus, both tissue temperature and cavitation can be monitored during FUS to ensure both safety and efficiency.
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The Spectral Airglow Temperature Imager is an instrument for ground-based spectroscopic measurements of the night-glow atmosphere emissions. This instrument was developed specially for gravity wave investigation. The measured airg...
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The Spectral Airglow Temperature Imager is an instrument for ground-based spectroscopic measurements of the night-glow atmosphere emissions. This instrument was developed specially for gravity wave investigation. The measured airglow spectra are matched to synthetic spectra calculated in advance for determination of the temperature in the mesopause region where the radiation maximum of some O_2 emissions is situated. The synthetic spectra are transformed into a format which corresponds to the measured spectra in order to be matched. This transformation is based on the known values of the refractive index and the central wavelength of the interference filter used. A substantial part of the processing algorithms of the SATI images is connected with determination of these two filter parameters. The results of the original and newly-proposed algorithms for filter parameter calculation and their importance for the final results for temperature determination on the basis of the O_2 (864-868 nm) emission measurements are presented. Considerable systematic differences (~20 K) between temperatures at different points in the mesopause retrieved by the two algorithms are established. The advantage of the proposed algorithm over the original one is illustrated by retrieved rotational temperatures and by lower error values. Furthermore, the irregular errors in the nocturnal variation of the temperature retrieved by the original algorithm are absent when the proposed approach is applied. The error investigation in the calculations and the stability of the individual components of the processing algorithms and the calculation models may be helpful in achieving better results and enhancing the potentialities of the SATI instrument.
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摘要 :
The Spectral Airglow Temperature Imager (SATI) instrument registers airglow coming from an annular mesopause segment. The temperatures of various points of this segment are retrieved by sectors of the registered images containing ...
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The Spectral Airglow Temperature Imager (SATI) instrument registers airglow coming from an annular mesopause segment. The temperatures of various points of this segment are retrieved by sectors of the registered images containing spectral information. A stage of SATI spectrogram processing connected with deriving spectral information from images and the determination of the rotational temperature of oxygen molecules emitting at the altitude of the mesopause is considered. A "moving sector" approach for sector spectra calculation is proposed. Typical for this approach is the possibility for varying the number of calculated sector spectra from one image and the sector angle. The sector angle may be selected depending on the quality features of the images. Two versions, one based on averaging and a second - based on finding the median of the values of all pixels at equal distance from the image center are developed. The determination of a mean temperature based on a whole image mean spectrum is considered as a potential source of systematic and gross errors. A determination of the mean temperature by averaging sector temperatures is proposed. Applying criteria for evalu ating the usability of sector temperatures based on azimuthal distribution of sector errors, emission intensities and backgrounds is possible. The moving sector approach is useful with the possibility for a detailed visual evaluation of the azimuthal distribution of retrieved sector variables - rotational temperature, emission rate, background and error.
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The advantages of noninvasive, fast speed, low-cost, and nonionizing radiation hazard have made electrical impedance tomography (EIT) an attractive imaging technology in geological, medical, and industrial applications. However, t...
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The advantages of noninvasive, fast speed, low-cost, and nonionizing radiation hazard have made electrical impedance tomography (EIT) an attractive imaging technology in geological, medical, and industrial applications. However, the EIT image has low spatial resolution due to the limited number of independent measurements and soft-field property. Focused on the fact that, in some applications, the conductivity variation exists only in part of the sensing field, this paper proposes a new strategy to enhance the image quality by restricting the image reconstruction within a region of interest (RROI). Compared with the conventional image reconstruction over the entire sensing field, the proposed strategy of RROI can improve regional image resolution effectively without increasing the number of electrodes and the complexity of the data acquisition system. The implementation of a conventional sensitivity-theorem-based conjugate gradient algorithm with the proposed RROI strategy is presented, and the improvement of image spatial resolution in region of interest is demonstrated by both simulations and phantom experiments.
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Axle box bearing is an important part of the rotating part of the bogie, and its state is related to the running safety of the train. For fault diagnosis and condition monitoring, vibration and temperature are measured from the bo...
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Axle box bearing is an important part of the rotating part of the bogie, and its state is related to the running safety of the train. For fault diagnosis and condition monitoring, vibration and temperature are measured from the bogie. However, installing additional sensing devices on the bogie increases manufacturing cost and can only obtain the information of a single point. In this article, we use the infrared monitoring system beside the railway to obtain global temperature information of the axle box. Aiming at a large number of infrared images with high noise caused by motion, this article presents a rapid position method of axle box based on image processing and infrared image characteristics. This article extracted G component as the input image, proposed adaptive temperature multicenter of gravity positioning method and curve detection method with the fitting radius of the boundary as shape descriptor to label the target image, and then used continuous-frame information to rapidly position the axle box based on the target image. The verification is carried out on six groups of real data. The results demonstrate the proposed method has 100% positioning accuracy, and the average time of each group is 11.77 s. The proposed method is more effective for images with high noise and blurred edges caused by motion. And on the premise of good robustness to ambient temperature and slight image deformation, it can also meet the real-time requirements, which can better adapt to the complex environment in practical engineering applications.
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The success of any minimally invasive treatment procedure can be enhanced significantly if combined with a robust noninvasive imaging modality that can monitor therapy in real time. Quantitative ultrasound (QUS) imaging has been w...
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The success of any minimally invasive treatment procedure can be enhanced significantly if combined with a robust noninvasive imaging modality that can monitor therapy in real time. Quantitative ultrasound (QUS) imaging has been widely investigated for monitoring various treatment responses such as chemotherapy, radiation, and thermal therapy. Previously, we demonstrated the feasibility of using spectral-based QUS parameters to monitor high-intensity focused ultrasound (HIFU) treatment of in situ tumors in euthanized rats [Ultrasonic Imaging 36(4), 239-255, 2014]. In the present study, we examined the use of spectral-based QUS parameters to monitor HIFU treatment of in vivo rat mammary adenocarcinoma tumors (MAT) where significant tissue motion was present. HIFU was applied to tumors in rats using a single-element transducer. During the off part of the HIFU duty cycle, ultrasound backscatter was recorded from the tumors using a linear array co-aligned with the HIFU focus. A total of 10 rats were treated with HIFU in this study with an additional sham-treated rat. Spectral parameters from the backscatter coefficient, i.e., effective scatterer diameter (ESD) and effective acoustic concentration (EAC), were estimated. The changes of each parameter during treatment were compared with a temperature profile recorded by a fine-needle thermocouple inserted into the tumor a few millimeters behind the focus of the HIFU transducer. The mean ESD changed from 121 ± 6 to 81 ± 8 μm (p-value = 0.0002), and the EAC changed from 33 ± 2 to 46 ± 3 dB/cm3 (p-value = 0.0002) during HIFU exposure as the temperature increased on average from 38.7 ± 1.0°C to 64.2 ± 2.7°C. The changes in ESD and EAC were linearly correlated with the changes in tissue temperature during the treatment. When HIFU was turned off, the ESD increased from 81 ± 8 to 121 ± 7 μm and the EAC dropped from 46 ± 3 to 36 ± 2 dB/cm3 as the temperature decreased from 64.2 ± 2.7°C to 45 ± 2.7°C. QUS was demonstrated in vivo to track temperature elevations caused by HIFU exposure.
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摘要 :
Magnetic Resonance Imaging (MRI) is a powerful imaging tool that combined with the use of contrast agents (CA) provides meaningful and crucial information both in the research and clinical settings. In recent years, strides have b...
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Magnetic Resonance Imaging (MRI) is a powerful imaging tool that combined with the use of contrast agents (CA) provides meaningful and crucial information both in the research and clinical settings. In recent years, strides have been taken towards the development of new CAs with enhanced capabilities (specificity, responsiveness, multimodality ...) to better diagnose and monitor physiological and pathological conditions in the body. Despite recent development, there are still challenges in the use of MRI to quantify specific functional or metabolic processes. The application of a ratiometric approach, in which images are acquired from the same sample using two different MR acquisitions, has potential to greatly improve the utility of MRI. In order to make this ratiometric approach work, a new generation of ratiometric probes are being developed which will be discussed in this review, classifying them based on the biological parameter under study as well as on the ratiometric analysis approach. Finally, the advantages and feasibility of using this methodology in a routine way will also be discussed. (C) 2021 Elsevier B.V. All rights reserved.
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