Discrimination of lung cancer and adjacent normal tissues based on permittivity by optimized probabilistic neural network / 南方医科大学学报

OBJECTIVE@#To propose a probabilistic neural network classification method optimized by simulated annealing algorithm (SA-PNN) to discriminate lung cancer and adjacent normal tissues based on permittivity.@*METHODS@#The permittivity of lung tumors and the adjacent normal tissues was measured by an open-ended coaxial probe, and the statistical dependency (SD) algorithm was used for frequency screening.The permittivity associated with the selected frequency points was taken as the characteristic variable, and SA-PNN was used to discriminate lung cancer and the adjacent normal tissues.@*RESULTS@#Three frequency points, namely 984 MHz, 2724 MHz and 2723 MHz, were selected by SD algorithm.SA-PNN was used to discriminate 200 samples with the permittivity at the 3 frequency points as the characteristic variable.After 10-fold cross-validation, the final discrimination accuracy was 92.50%, the sensitivity was 90.65%, and the specificity was 94.62%.@*CONCLUSIONS@#Compared with the traditional probabilistic neural network, BP neural network, RBF neural network and the classification discriminant analysis function (Classify) in MATLAB, the proposed SA-PNN has higher accuracy, sensitivity and specificity for discriminating lung cancer and the adjacent normal tissues based on permittivity.

Research on 7.0 T Magnetic Resonance Based Electrical Properties Tomography Based on Bloch-Siegert Shift / 中国医疗器械杂志

Magnetic resonance based electrical properties tomography (MREPT) is a different method from proton density imaging, Bloch-Siegert shift (BSS) is used in this paper to reconstruct the radiofrequency (RF) field amplitude and calculate the distribution of the permittivity constant. The phase of the RF field is approximated by the phase component of the magnetization intensity, and the conductivity distribution is calculated. In the experiment, Bruker 7.0 T magnetic resonance device was used to image two water models and in vivo Balb/c mice to obtain the image of electrical characteristics. Experimental results show that the Bloch-siegert B1+ image is significantly more efficient than the double-angle B1+ image. The study can provide a reference for selecting appropriate B1 mapping technology for B1 field imaging of electrical characteristics organizations, and provide basic research support for promoting the practical application of magnetic resonance characteristics.

Monitoring osseointegrated prosthesis loosening and fracture using electrical capacitance tomography

A noncontact, noninvasive, electrical permittivity imaging technique is proposed for monitoring loosening of osseointegrated prostheses and bone fracture. The proposed method utilizes electrical capacitance tomography (ECT), which employs a set of noncontact electrodes, arranged in a circular fashion around the imaging area, for electrical excitations and measurements. An inverse reconstruction algorithm was developed and implemented to reconstruct the electrical permittivity distribution of the interrogated region from boundary capacitance measurements. In this study, osseointegrated prosthesis phantoms were prepared using plastic rods and Sawbone femur specimens, which were subjected to prosthesis loosening and fracture monitoring tests. The results demonstrated that the spatial location and extent of prosthesis loosening and bone fracture could be estimated from the ECT reconstructed permittivity maps. The resolution of the reconstructed images was further enhanced by a limited region tomography algorithm, and its accuracy in terms of identifying the severity, location, and shape of bone fracture was also investigated and compared with conventional full region tomography.

The open-ended coaxial line method for colorectal cancer detection and depth evaluation of tumor invasion / 实用医学杂志

Objective To confirm whether the open-ended coaxial line is effective in detection of the differences in dielectric properties between colorectal cancer tissues and surrounding normal tissues and evaluation of the depth of tumor invasion. Methods The open-ended coaxial line system at frequencies ranging from 50 to 500 MHz in 98 freshly excised colorectal cancerous specimens obtained from the operating theatre of Zhujiang Hospital, was used to detect both the relative permittivity and conductivity on the serosal surface of the carcinoma nidus, the mucosa of the carcinoma nidus, and the mucosa of the surgical resection margin. Pathological examinations were conducted on each specimen after surgery. Results The values for relative permittivity and conductivity of the colorectal cancerous mucosa were significantly higher than those of the normal mucosa (P < 0.01). For the tumor which had invaded or penetrated the serosa (stage ≥ T3), the dielectric properties of both the cancerous serosa and mucosa were higher than the one restricted to muscularis propria or less intestine wall (stage < T3) over the measured frequency range, and there existed statistical differences at the common frequencies of 213 MHz and 426 MHz. Conclusion The open-ended coaxial line system may result in fast and effective diagnostic differentiation between cancerous and normal colorectal tissues as well as reasonable assessment of the tumor infiltration depth.

Improving the measurement precision of the phantom model by network decomposition method / 医疗卫生装备

It is a kind of precise method tomeasure the complex permittivities of the phantom model by vector network analyzer.But it is difficult tomeasure them accurately because the phantom model is jelly-like gel and is hard tobe shaped.Network decompositon method can be used toresolve it and it has great meaning tostudy the phantom model simulating the biologic tissue.

Measuring the complex permittivity of phantom model by perturbation method / 医疗卫生装备

It is the measurement of high-loss dielectric to measure the permittivity and conductivity of biologic tissue.But now it is difficult to measure them accurately.Good result is got by measuring complex permittivity of phantom model at2450MHz using perturbation method,which is meaningful for the research on biologic tissue simulation by phantom model.

Electrophysiological Properties of Frequency Domain in Rats' Skeletal Muscle / 中国运动医学杂志

Objective To study the electrophysiological properties of rat skeletal muscle within the frequency from 100Hz to 100MHz.Methods The AC impedance of rat sural muscle tissues was measured using the Agilent 4294A impedance analyzer, then the electrophysiological properties of the normal rat sural muscle cells were established in the respect of cell dielectric spectroscopy, Cole-Cole plots, spectrum of loss factor and loss tangent.Results (1) The dielectric response of rat sural muscle cells was frequency-dependent, such as increase in frequency caused decrease in permittivity. At the same time the conductivity trended to arise; (2) The dielectric parameters(?_L,?_h,?_L,?_h,△?″_ max,△tg?_ max,f_ C1,f_ C2) cell fiber parallel to the applied electric field differed from that cell fiber perpendicular to the applied electric field; (3) The effect of alternating current electric field on rat sural muscle cells showed a dielectric dispersion phenomenon, representing two characteristic frequency: the 1 st frequency(f_ C1(∥)=f_ C1(⊥)=1.02 kHz) and 2 nd frequency(f_ C2(∥)=59.31 kHz,f_ C2(⊥)=380.04kHz). Conclusion The method for studying the electrophysiological properties of rat skeletal muscle cells was established in the respect of the frequency domain,providing a possibility for investigating muscle fatigue in the future.