BIOLUMINESCENCE TOMOGRAPHY： BIOMEDICAL BACKGROUND,MATHEMATICAL THEORY,AND NUMERICAL APPROXIMATION

Over the last couple of years molecular imaging has been rapidly developed to study physiological and pathological processes in vivo at the cellular and molecular levels. Among molecular imaging modalities, optical imaging stands out for its unique advantages, especially performance and cost-effectiveness. Bioluminescence tomography （BLT） is an emerging optical imaging mode with promising biomedical advantages. In this survey paper, we explain the biomedical significance of BLT, summarize theoretical results on the analysis and numerical solution of a diffusion based BLT model, and comment on a few extensions for the study of BLT.     

Product measurements and fully symmetric measurements in qubit-pair tomography: A numerical study

State tomography on qubit pairs is routinely carried out by measuring the two qubits separately, while one expects a higher efficiency from tomography with highly symmetric joint measurements of both qubits. Our numerical study of simulated experiments does not support such expectations.     

Laser absorption spectroscopy for combustion diagnosis in reactive flows: A review

Laser absorption spectroscopy (LAS) has been rapidly developed and widely applied to combustion diagnosis in recent decades. As a cost-effective tool for measuring multiple combustion parameters, LAS provides unique properties in terms of accuracy and sensitivity for understanding the reactions and kinetics in reactive flows. Line-of-sight and tomographic LAS techniques have stimulated numerous applications and been proved to be robust for in situ combustion diagnosis in uniform and non-uniform combustion fields, respectively. This review highlights the breakthroughs in the evolution of LAS techniques from the viewpoints of key principles, sensors and instrumentations developed for combustion diagnosis, with particular emphasis on a series of spatially-resolved LAS techniques with their recent applications on obtaining high-fidelity measurement results with minimal intrusion to the practical combustors. Along the way, we note some challenges and requirements for further development of the LAS-based combustion diagnosis.     

The asymptotic behaviour of weak solutions to the forward problem of electrical impedance tomography on unbounded three‐dimensional domains

The forward problem of electrical impedance tomography on unbounded domains can be studied by introducing appropriate function spaces for this setting. In this paper we derive the point‐wise asymptotic behaviour of weak solutions to this problem in the three‐dimensional case. Copyright © 2008 John Wiley & Sons, Ltd.     

Study on scattering correction in fast neutron tomography at NECTAR facility

Fast neutron tomography has been established as an inspection and detection tool at the NECTAR facility at the FRM-II reactor.Scattered neutrons from the object become a major disturbance and bring in artifacts and deviations in reconstruction results,especially for hydrogenous material object.In this article,an iterative scattering correction method for fast neutron tomography was proposed.In each loop of iteration the scattering component of the projections will be simulated by Monte-Carlo program MCNPX based on the previous reconstruction result and then it will be subtracted from original projections.The differences between scattering components at different perspectives were quantitatively evaluated and an average scattering component image was used for all projections finally.Smooth and uniform slices with more clear edges were obtained and the new reconstructed attenuation coefficients are quite close to the real one compared to the results without scattering correction,in which case the relative error of the reconstructed attenuation coefficients is about 10%–30%.     

Detection of diminished response to cold pressor test in smokers: Assessment using phase-contrast cine magnetic resonance imaging of the coronary sinus

Purpose

The purposes of this study were to evaluate the reproducibility for measuring the cold pressor test (CPT)-induced myocardial blood flow (MBF) alteration using phase-contrast (PC) cine MRI, and to determine if this approach could detect altered MBF response to CPT in smokers.

Materials and methods

After obtaining informed consent, ten healthy male non-smokers (mean age: 28 ± 5 years) and ten age-matched male smokers (smoking duration ≥ 5 years, mean age: 28 ± 3 years) were examined in this institutional review board approved study. Breath-hold PC cine MR images of the coronary sinus were obtained with a 3 T MR imager with 32 channel coils at rest and during a CPT performed after immersing one foot in ice water. MBF was calculated as coronary sinus flow divided by the left ventricular (LV) mass which was given as a total LV myocardial volume measured on cine MRI multiplied by the specific gravity (1.05 g/mL).

Results

In non-smokers, MBF was 0.86 ± 0.25 mL/min/g at rest, with a significant increase to 1.20 ± 0.36 mL/min/g seen during CPT (percentage change of MBF (?MBF (%)); 39.2% ± 14.4%, p < 0.001). Inter-study reproducibility for ?MBF (%) measurements by different MR technologist was good, as indicated by the intraclass correlation coefficient of 0.93 and reproducibility coefficient of 10.5%. There was no significant difference between smokers and non-smokers for resting MBF (0.85 ± 0.32 mL/min/g, p = 0.91). However, ?MBF (%) in smokers was significantly reduced (-4.0 ± 32.2% vs. 39.2 ± 14.4%, p = 0.011).

Conclusion

PC cine MRI can be used to reproducibly quantify MBF response to CPT and to detect impaired flow response in smokers. This MR approach may be useful for monitoring the sequential change of coronary blood flow in various potentially pathologic conditions and for investigating its relationship with cardiovascular risk.     

Assessment of different fixation protocols on the presence of membrane-bound vesicles in Caco-2 cells: A multidimensional view by means of correlative light and 3-D transmission electron microscopy

Herein, we present a comparative analysis of a variety of chemical and physical fixation protocols for the specific visualisation of the membrane-bound vesicles (MBVs) in the Caco-2 colorectal cancer (CRC) cell line. In so doing, we validated the applicability of specific specimen preparation protocols for the preservation and contrasting of membrane-associated vesicles. Next, by employing the best respective chemical (GOT) and physical (SHPF) fixation methods for the application of transmission electron tomography and modelling we were able to characterise MBVs in three-dimensions and at the nanometer scale. In the second part of this study, we employ a correlative light and electron microscopy (CLEM) approach in order to determine which vesicular compartments are implicated in the uptake of FITC-BSA as a model protein drug. In so doing, we provide a solid foundation for future studies investigating chemotherapeutic drug uptake, transport and fate in cancer cell lines.     

金属圆柱腔体中使用非均一背景增强微波断层成像

针对基于圆柱金属腔体的微波断层成像系统,提出了一种利用非均一背景增强系统获取目标信息能力的方法.该方法通过在腔体内放置已知物体构成非均一背景,这样不但能利用背景的先验信息,而且可以增加等效辐射源对目标进行探测.首先,利用矩量法计算圆柱金属腔体内非均一背景的格林函数和离散积分算子,并对离散积分算子进行奇异值谱和条件数分析,在理论上证明该方法的可行性;然后,利用基于有限元的对比源逆成像法对均一背景、有耗非均一背景和无耗非均一背景三种情况进行仿真研究;最后对仿真结果进行了误差分析和比较.仿真结果表明,该方法可以提高反演收敛速度和结果准确度,有耗非均一背景略优于无耗非均一背景.该方法可以在不改变硬件系统和算法的情况下得到更准确的反演结果,可应用于医学成像与工业无损探测.