Using electroencephalogram (EEG) signal to control external devices has always been the research focus in the field of brain-computer interface (BCI). This is especially significant for those disabilities who have lost capacity of movements. In this paper, the P300-based BCI and the microcontroller-based wireless radio frequency (RF) technology are utilized to design a smart home control system, which can be used to control household appliances, lighting system, and security devices directly. Experiment results showed that the system was simple, reliable and easy to be populirised.
In the development of radio frequency (RF) coils for better quality of the mini-type permanent magnetic resonance imager for using in the small animal imaging, the solenoid RF coil has a special advantage for permanent magnetic system based on analyses of various types of RF coils. However, it is not satisfied for imaging if the RF coils are directly used. By theoretical analyses of the magnetic field properties produced from the solenoid coil, the research direction was determined by careful studies to raise further the uniformity of the magnetic field coil, receiving coil sensitivity for signals and signal-to-noise ratio (SNR). The method had certain advantages and avoided some shortcomings of the other different coil types, such as, birdcage coil, saddle shaped coil and phased array coil by using the alloy materials (from our own patent). The RF coils were designed, developed and made for keeled applicable to permanent magnet-type magnetic resonance imager, multi-coil combination-type, single-channel overall RF receiving coil, and applied for a patent. Mounted on three instruments (25 mm aperture, with main magnetic field strength of 0.5 T or 1.5 T, and 50 mm aperture, with main magnetic field strength of 0.48 T), we performed experiments with mice, rats, and nude mice bearing tumors. The experimental results indicated that the RF receiving coil was fully applicable to the permanent magnet-type imaging system.
Trying to provide ultrasonic image-aid measures for quantitative diagnosis and dynamic monitoring of liver fibrosis, we propose two scoring methods for liver fibrosis tissue in vivo, based on ultrasound radio frequency (RF) time series in this paper. Firstly, RF echo signals of human liver were recorded in this study. Then one of the recorded frame RF data was demodulated to be B model image. After that, a region of interest (ROI) in the B model image was selected. For each point in the ROI, its all frame data were acquired so that RF time series were formed. An SMR (size measure relationship) fractal dimension and six spectral features were extracted from RF time series in the ROI. With relative deviation and Fisher's discriminant ratio, seven features were weighted and summed so that the liver tissues' scores were obtained, Score-rd and Score-fisher, respectively. Area under ROC curve (AUC) and a support vector machine (SVM) were used to evaluate whether these scoring methods would be useful in distinguishing normal and cirrhosis tissues. Experimental results are shown as follows: Score-rd's AUC was 0.843, while Score-fisher was 0.816, SVM classification accuracies were both up to 87.5%. This proved that our proposed scoring methods were effective in distinguishing normal and cirrhosis tissues. Score-rd and Score-fisher have potential for clinical applications. They can also provide quantitative references for liver fibrosis diagnosis.
In this paper, a new probe is proposed for the in vivo dielectric measurement of anisotropic tissue in radio frequency band, which could accomplish the dielectric measurement in perpendicular directions by one operation. The simulative studies are performed in the frequency range from 1–1 000 MHz in order to investigate the influence of probe dimension on the energy coupling and sensitivity of measurement. The suitable probe is designed and validated for the actual measurement in this frequency band. According to the simulation results, the energy coupling of the probe could be kept below –12 dB in the frequency range from 200–400 MHz with high sensitivity of measurement for the dielectric properties of anisotropic tissue. That indicates the new type of probe has the potential to achieve the dielectric measurement of anisotropic tissue in radio frequency band and could avoid the measurement error by multi-operations in the conventional method. This new type of probe could provide a new method for the in vivo dielectric measurement of anisotropic tissue in radio frequency band.
For rat spinal magnetic resonance imaging (MRI) experiments, due to the lower main magnetic field strength, shallower detected depth and poor spatial compatibility of the traditional radio frequency (RF) coil, the image signal-to-noise ratio (SNR) of rat spinal was rather lower. In this paper, a RF coil for rat spinal MRI at 9.4 T was developed to improve the image quality and at the same time to avoid the space limitation while scanning in special conditions (cardiac catheterization, etc.). In this article, open birdcage structure was built and magnetic field distribution was calculated. The phantom and rat spine MRI imaging were experimented at 9.4 T to verify the advantage of the coil in rat spine MRI application.
Early screening is an important means to reduce breast cancer mortality. In order to solve the problem of low breast cancer screening rates caused by limited medical resources in remote and impoverished areas, this paper designs a breast cancer screening system aided with portable ultrasound Clarius. The system automatically segments the tumor area of the B-ultrasound image on the mobile terminal and uses the ultrasound radio frequency data on the cloud server to automatically classify the benign and malignant tumors. Experimental results in this study show that the accuracy of breast tumor segmentation reaches 98%, and the accuracy of benign and malignant classification reaches 82%, and the system is accurate and reliable. The system is easy to set up and operate, which is convenient for patients in remote and poor areas to carry out early breast cancer screening. It is beneficial to objectively diagnose disease, and it is the first time for the domestic breast cancer auxiliary screening system on the mobile terminal.
ObjectiveTo investigate the dynamic changes of nodule volume in benign thyroid tumors after radiofrequency ablation (RFA), and to analyze the predictive value of risk factors for nodule regeneration. MethodsA total of 165 patients with benign thyroid nodules who received RFA treatment in the People’s Hospital of Yuechi County from June 2019 to June 2021 were retrospectively collected and divided into small nodule volume group (≤15 mL, n=116) and large nodule volume group (>15 mL, n=49) according to the median nodule volume at admission. The clinical data and serological data of the two groups were compared. Multivariate Cox proportional hazard regression model was used to adjust confounding factors to explore the relationship between initial nodule volume, vascular density, nodule location near critical structure and postoperative nodule regeneration in patients with benign thyroid nodules. According to the proposed Nomogram of the model, Bootstrap method was adopted for sampling verification, calibration curve was adopted to evaluate the calibration degree of the model, and area under the curve (AUC) of receiver operating characteristics (ROC) curve was adopted to evaluate the model differentiation. ResultsIn the small volume nodule group, the proportion of unilateral nodule was higher, and the preoperative beauty score, preoperative symptom score, radiofrequency power, ablation time, total energy, operative time, intraoperative blood loss and hospital stay were lower or short, P<0.05. The change value of thyroid stimulating hormone (TSH), free triiodothyronine (FT3), catalase (CAT) after operation in small volume nodule group were higher than those in the large nodule volume group (P<0.05), but change value of the free thyroxine (FT4), malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) were lower than those in the large nodule volume group (P<0.05). At 1, 3, 6, 12, and 24 months after RFA operation, the nodule volume of the two groups decreased successively, and volume reduction rate (VRR) increased successively. The changes of nodule volume and VRR in the small nodule volume group were better than those in the large nodule volume group. In the large nodule group, the nodule volume was larger at 1, 3, 6, 12, and 24 months after operation, and the VRR was higher at 1 month after operation, the regeneration time was shorter, the number of residual nodules was higher, and the initial ablation rate (IAR) was lower (P<0.05). After adjusting for age, gender and other factors, the correlation effect value increased with the increase of initial volume and blood vessel density, and the differences in trend test were statistically significant (Ptrend <0.05). Nodules located near the critical structure had an increased risk of regeneration (OR=1.76, P<0.001). The Nomogram constructed according to the multi-factor model has good differentiation (AUC before and after ROC curve validation were 0.854 and 0.814, respectively) and accuracy (mean absolute error of 0.023). ConclusionsRFA achieved clinically relevant volume reduction in both ≤15 mL and >15 mL of single benign thyroid nodules, lasting for at least 2 years. However, the nodule VRR and cosmetic effect were better in the small volume nodule group, and the initial nodule volume, blood vessel density and location were closely related to nodule regeneration. The Nomogram model showed good differentiation and accuracy in predicting the risk of nodule regeneration, providing strong support for clinical decision-making.