Volume 21, Issue 6

The aim of the experiments was to check the feasibility of pulmonary perfusion imaging by functional electrical impedance tomography (EIT) and to compare the EIT findings with electron beam computed tomography (EBCT) scans. In three pigs, a Swan-Ganz catheter was positioned in a pulmonary artery branch and hypertonic saline solution or a radiographic contrast agent were administered as boli through the distal or proximal openings of the catheter. During the administration through the proximal opening, the balloon at the tip of the catheter was either deflated or inflated. The latter case represented a perfusion defect. The series of EIT scans of the momentary distribution of electrical impedance within the chest were obtained during each saline bolus administration at a rate of 13/s. EBCT scans were acquired at a rate of 3.3/s during bolus administrations of the radiopaque contrast material under the same steady-state conditions. The EIT data were used to generate local time-impedance curves and functional EIT images showing the perfusion of a small lung region, both lungs with a perfusion defect and complete both lungs during bolus administration through the distal and proximal catheter opening with an inflated or deflated balloon, respectively. The results indicate that EIT imaging of lung perfusion is feasible when an electrical impedance contrast agent is used.

实验的目的是检验通过功能性电阻抗断层成像（EIT）进行肺灌注成像的可行性，并将EIT结果与电子束计算机断层扫描（EBCT）进行比较。在三头猪体内，将Swan-Ganz导管置于肺动脉分支，并通过导管的远端或近端开口注射高渗盐水溶液或放射造影剂。通过近端开口注射时，导管尖端的球囊要么放气要么充气。后一种情况代表灌注缺损。在每次盐水团注过程中，以13次/秒的速率获取胸部内电阻抗瞬时分布的EIT扫描序列。在相同稳态条件下，以3.3次/秒的速率获取注射放射造影剂团注时的EBCT扫描。EIT数据用于生成局部时间-阻抗曲线和功能性EIT图像，这些图像分别显示了在通过导管远端和近端开口（球囊充气或放气）注射团注时，小肺区域、双肺伴灌注缺损以及完整双肺的灌注情况。结果表明，当使用电阻抗造影剂时，EIT肺灌注成像是可行的。

Electrical impedance spectroscopy (EIS) is a potential, noninvasive technique to image women for breast cancer. Studies have shown characteristic frequency dispersions in the electrical conductivity and permittivity of malignant versus normal tissue. Using a multifrequency EIS system, we imaged the breasts of 26 women. All patients had mammograms ranked using the American College of Radiology (ACR...

电阻抗光谱成像（EIS）是一种潜在的无创技术，可对女性进行乳腺癌成像。研究表明，恶性组织与正常组织的电导率和介电常数存在特征频率色散。我们使用多频EIS系统对26名女性的乳房进行了成像。所有患者都进行了乳房X线摄影检查，并根据美国放射学会（ACR）标准进行分级。

Results of development and testing of the new medical imaging system are described. The system uses a planar array consisting of 256 electrodes and enables obtaining images of the three-dimensional conductivity distribution in regions below the skin's surface up to several centimeters deep. The developed measuring system and image reconstruction algorithm can be used for breast tissue imaging and ...

描述了新型医学成像系统的开发和测试结果。该系统采用由256个电极组成的平面阵列，能够获取皮肤表面以下数厘米深区域的三维电导率分布图像。所开发的测量系统和图像重建算法可用于乳腺组织成像等……

Recently, a new static resistivity image reconstruction algorithm is proposed utilizing internal current density data obtained by magnetic resonance current density imaging technique. This new imaging method is called magnetic resonance electrical impedance tomography (MREIT). The derivation and performance of J-substitution algorithm in MREIT have been reported as a new accurate and high-resoluti...

最近，提出了一种利用磁共振电流密度成像技术获得的内部电流密度数据的新型静态电阻率图像重建算法。这种新的成像方法被称为磁共振电阻抗成像（MREIT）。MREIT中J-替换算法的推导和性能已被报道为一种新的精确且高分辨率...

A direct (noniterative) reconstruction algorithm for electrical impedance tomography in the two-dimensional (2-D), cross-sectional geometry is reviewed. New results of a reconstruction of a numerically simulated phantom chest are presented. The algorithm is based on the mathematical uniqueness proof by A.I. Nachman [1996] for the 2-D inverse conductivity problem. In this geometry, several of the c...

回顾了一种用于二维（2-D）横截面几何的电阻抗断层成像的直接（非迭代）重建算法。给出了数值模拟的胸部体模重建的新结果。该算法基于A.I. Nachman [1996] 对二维逆电导率问题的数学唯一性证明。在这种几何结构中，几个...

We apply electrical impedance tomography to detect and localize brain impedance changes associated with stroke. Forward solutions are computed using the finite-element method in two dimensions. We assume that baseline conductivity values are known for the major head tissues, and focus on changes in the brain compartment only. We use singular-value decomposition (SVD) to show that different impedan...

我们应用电阻抗成像来检测和定位与脑卒中相关的脑阻抗变化。正向解采用二维有限元方法计算。假设主要头部组织的基线电导率值已知，并仅关注脑隔室的变化。我们使用奇异值分解（SVD）来展示不同的阻抗...

This paper concerns the modeling and interpretation of harmonies observed as a result of the nonlinear electrical properties of biomedical electrode/electrolyte interfaces. The higher order harmonics have been calculated assuming that the nonlinearity of the interfacial impedance is dominated at low frequencies by the nonlinear faradaic charge transfer resistance. The harmonic distribution in the ...

本文关注生物医学电极/电解质界面非线性电特性所产生的谐波的建模与解释。假设在低频下，界面阻抗的非线性主要由非线性法拉第电荷转移电阻主导，计算了高阶谐波。谐波分布...

Breast cancer diagnosis may be improved by electrical immittance measurements. We have developed a novel method, space-frequency MUItiple Signal Classification (MUSIC), to determine three-dimensional positions and electrical parameters of focal lesions from multifrequency trans-admittance data recorded with a planar electrode array. A homogeneous infinite volume conductor containing focal inhomoge...

乳腺癌诊断可以通过电阻抗测量得到改善。我们开发了一种新方法——空间频率多信号分类（MUSIC），用于从平面电极阵列记录的多频跨导纳数据中确定局灶性病变的三维位置和电参数。一个包含局灶性不均匀性的均匀无限体积导体...

In this paper, we review some numerical techniques based on the linear Krylov subspace iteration that can be used for the efficient calculation of the forward and the inverse electrical impedance tomography problems. Exploring their computational advantages in solving large-scale systems of equations, we specifically address their implementation in reconstructing localized impedance changes occurr...

本文回顾了一些基于线性Krylov子空间迭代的数值技术，这些技术可用于高效计算电阻抗断层成像的正问题和逆问题。探讨了它们在求解大规模方程组中的计算优势，特别关注了在重建局部阻抗变化时的实现...

We studied dielectrical properties of canine myocardium during acute ischemia and hypoxia using dielectrical spectroscopy method at frequency spectrum from 100 kHz to 6 GHz. This study was conducted on a group of six canines with acute ischemia and seven canines with hypoxia. Hypoxia (10% for 30 min) decreases myocardial resistance (/spl rho/), while the dielectrical permittivity (/spl epsi/') of ...

我们采用介电谱方法，在100 kHz至6 GHz频率范围内研究了犬心肌在急性缺血和缺氧时的介电特性。本研究在一组六只急性缺血犬和七只缺氧犬上进行。缺氧（10% 30分钟）降低心肌电阻抗（ρ），而介电常数（ε'）...

In the inverse conductivity problem, as in any ill-posed inverse problem, regularization techniques are necessary in order to stabilize inversion. A common way to implement regularization in electrical impedance tomography is to use Tikhonov regularization. The inverse problem is formulated as a minimization of two terms: the mismatch of the measurements against the model, and the regularization f...

在逆电导率问题中，如同任何不适定逆问题一样，需要正则化技术来稳定反演。在电阻抗成像中，实现正则化的一种常见方式是使用吉洪诺夫正则化。该逆问题被表述为两项的最小化：测量值与模型之间的失配，以及正则化项...

A new postprocessing algorithm was developed for the diagnosis of breast cancer using electrical impedance scanning. This algorithm automatically recognizes bright focal spots in the conductivity map of the breast. Moreover, this algorithm discriminates between malignant and benign/normal tissues using two main predictors: phase at 5 kHz and crossover frequency, the frequency at which the imaginar...

开发了一种新的后处理算法，用于使用电阻抗扫描进行乳腺癌诊断。该算法自动识别乳房电导率图中的明亮焦点斑。此外，该算法使用两个主要预测因子区分恶性组织和良性/正常组织：5 kHz时的相位和交叉频率，即虚部消失的频率...

We propose a new impedance imaging method, electromagnetic impedance tomography (EMIT), in which the boundary electric potential measurements in electrical impedance tomography (EIT) are augmented by measurements of the exterior magnetic field induced by the currents excited in the object by the standard EIT procedures. These magnetic measurements can be obtained reliably and inexpensively by simp...

我们提出了一种新的阻抗成像方法——电磁阻抗断层成像（EMIT），该方法通过标准EIT程序在物体中激励电流，并测量由此产生的外部磁场，从而增强了电阻抗断层成像（EIT）中的边界电位测量。这些磁场测量可以通过简单的方式可靠且低成本地获得…

Electrical impedance (EI) measurements conducted on the thorax contain useful information about the changes in blood volume that occur in the thorax during the heart cycle. The aim of this paper is to present a new (tomographic-like) method to obtain this relevant information with electrical impedance measurements, using a linear electrode array. This method is tested on three subjects and the res...

在胸腔上进行的电阻抗测量包含了心脏周期中胸腔血容量变化的有用信息。本文的目的是介绍一种新的（类似断层扫描的）方法，通过使用线性电极阵列的电阻抗测量来获取这些相关信息。该方法在三个受试者身上进行了测试，结果...

Previous studies have shown that tetrapolar electrical impedance spectroscopy measurements can identify cervical interstitial neoplasia with the same sensitivity and specificity as cervical smears. In the urinary bladder, the same technique yields significant differences (p < 0.05 at seven frequencies between 9.6 and 614 kHz) between normal and malignant urothelium, but is unable to classify indiv...

既往研究表明，四极电阻抗谱测量可以识别宫颈间质瘤，其敏感性和特异性与宫颈涂片相同。在膀胱中，相同技术在正常和恶性尿路上皮之间显示出显著差异（p < 0.05，在9.6至614 kHz之间的七个频率下），但无法对个体进行分类...

This paper describes a new method for scanning the conductivity of a tissue or an organ using a multielectrode impedance probe placed at the center of the region of interest. The long-term objective of the study is the evaluation, using an urethral impedance probe, of the lesion produced by ultrasound ablathermy of localized prostate cancer. The probe consists of electrodes placed at the surface o...

本文描述了一种使用位于感兴趣区域中心的多电极阻抗探头扫描组织或器官电导率的新方法。该研究的长期目标是使用尿道阻抗探头评估超声消融治疗局限性前列腺癌所产生的病灶。该探头由放置在表面的电极组成……

A framework to analyze the propagation of measurement noise through backprojection reconstruction algorithms in electrical impedance tomography (EIT) is presented. Two measurement noise sources were considered: noise in the current drivers and in the voltage detectors. The influence of the acquisition system architecture (serial/semi-parallel) is also discussed. Three variants of backprojection re...

提出了一种分析电阻抗断层成像（EIT）中反投影重建算法中测量噪声传播的框架。考虑了两种测量噪声源：电流驱动器和电压检测器中的噪声。还讨论了采集系统架构（串行/半并行）的影响。三种反投影变体...

In electrical impedance tomography, errors due to stray capacitance may be reduced by optimization of the reference phase of the demodulator. Two possible methods, maximization of the demodulator output and minimization of reciprocity error have been assessed, applied to each electrode combination individually, or to all combinations as a whole. Using an EIT system with a single impedance measurin...

在电阻抗断层成像中，通过优化解调器的参考相位可以减少杂散电容引起的误差。评估了两种可能的方法：最大化解调器输出和最小化互易误差，这些方法可单独应用于每个电极组合，或整体应用于所有组合。使用具有单阻抗测量的EIT系统...

In electrical impedance tomography, currents are applied to the body through electrodes that are attached to the surface and the corresponding surface voltages are measured. Based on these boundary measurements, the internal admittivity distribution of the body can be reconstructed. In order to improve the image quality it is necessary and useful to apply physiologically meaningful prior informati...

在电阻抗断层成像中，通过附着在体表的电极向人体施加电流，并测量相应的表面电压。基于这些边界测量，可以重建人体内部的导纳分布。为了提高图像质量，应用具有生理学意义的先验信息是必要且有益的...

The possibilities of identification of intraventicular haemorrhage with the aid of electrical impedance tomography are presented in this paper. On the base of the tomographic image of a human brain a simplified two-dimensional mathematical model of the human head is proposed. The mathematical model is relatively poor, but the main purpose of this paper is to investigate the possibility and precisi...

本文介绍了利用电阻抗断层成像识别脑室内出血的可能性。基于人类大脑的断层图像，提出了一种简化的人头二维数学模型。该模型相对粗糙，但本文的主要目的是研究这种可能性及其精确性...

A discrete coil EIT system is investigated for the general case of an eccentric circular inhomogeneity. The solution methodology of the forward problem of this system is explained. An optimization procedure using this forward problem solution is developed to find optimum currents that maximize the distinguishability. For an eccentric inhomogeneity problem, it is shown that the coil currents can be...

本文研究了一种用于一般偏心圆形非均匀体情况的离散线圈EIT系统。解释了该系统正问题的求解方法。利用该正问题解，开发了一种优化程序，以寻找最大化可分辨性的最优电流。对于偏心非均匀体问题，表明线圈电流可以...