An study of ultrasonic monitoring imaging of microwave ablation based on Nakagami statistic parameter / 生物医学工程学杂志

This paper explored the feasibility of using ultrasonic Nakagami statistic parameter imaging to evaluate the thermal lesion induced by microwave ablation (MWA) in porcine models. In this paper, thermal lesions were induced in livers and kidneys in 5 swines using a clinical MWA system. During this treatment progress, ultrasonic radiofrequency (RF) data were collected. The dynamic changes of Nakagami parameter in the thermal lesion were calculated, and the ultrasonic B-mode images and Nakagami images were reconstructed simultaneously. The contrast-to-noise ratio (CNR) between the thermal lesion and the surrounding normal tissue was calculated over the MWA procedure. After MWA, a bright hyperechoic region appeared in the ultrasonic Nakagami image as an indicator of the thermal lesion and this bright spot enlarged with lesion development during MWA exposure. The mean value of Nakagami parameter in the liver and kidney increased from 0.78 and 0.79 before treatment to 0.91 and 0.92 after treatment, respectively. During MWA exposure, the mean values of CNR calculated from the Nakagami parameter increased from 0.49 to 1.13 in the porcine liver and increased from 0.51 to 0.85 in the kidney, which were both higher than those calculated from the B-mode images. This study on porcine models suggested that the ultrasonic Nakagami imaging may provide an alternative modality for monitoring MWA treatment.

Genetic algorithm application to multi-focus patterns of 256-element phased array for focused ultrasound surgery / 生物医学工程学杂志

The genetic optimal algorithm and sound field calculation approach for the spherical-section phased array are presented in this paper. The in-house manufactured 256-element phased array focused ultrasound surgery system is briefly described. The on-axis single focus and off-axis single focus are simulated along with the axis-symmetric six-focus patter and the axis-asymmetric four-focus pattern using a 256-element phased array and the genetic optimal algorithm and sound field calculation approach. The experimental results of the described 256-element phased array focused ultrasound surgery system acting on organic glass and phantom are also analyzed. The results of the simulations and experiments confirm the applicability of the genetic algorithm and field calculation approaches in accurately steering three dimensional foci and focus.

Time-resolved fluorescence anisotropy measurement and its application in the research of biomacromolecule / 生物医学工程学杂志

In this symposium, we reviewed the principle and development of time-resolved fluorescence anisotropy measurement. Its method of measurement, characteristics and applications in the research of biomacromolecule, configuration and molecular structure have been discussed. Its potential applications are also illustrated.

MR-based assessment of pulmonary ventilation-perfusion in animal models / 中华放射学杂志

Objective To show the feasibility and value in the diagnosis of airway obstruction and pulmonary embolism with MR oxygen-enhanced ventilation combined with pulmonary perfusion imaging. Methods Eight canines were implemented for peripheral pulmonary embolism by intravenous injection of gelfoam granules at pulmonary segmental arterial level, and five of them were formed airway obstruction models by inserting self-made balloon catheter at second-bronchia. The oxygen-enhanced MR ventilation imaging was introduced by subtracting the images of pre- and post- inhaled pure oxygen. The MR pulmonary perfusion imaging was achieved by the first-pass contrast agent method. Moreover, the manifestation of MR ventilation and perfusion imaging was observed and contradistinguished with that of general pathologic anatomy, ventilation-perfusion scintigraphy, and pulmonary angiography. Results The manifestations of airway obstruction regions in MR ventilation and perfusion imaging were matched, but those of pulmonary embolism regions were dismatched. The defect range of airway obstruction in MR ventilation image was smaller than that in ventilation scintigraphy. The abnormal perfusion regions of pulmonary embolism were divided into defect regions and reduce regions based on the time courses of signal intensity changes. The sensitivity and specificity of diagnosis on pulmonary embolism by MR ventilation combined with perfusion technique were 75.0% and 98.1%. The diagnostic results were in good coherence with ventilation-perfusion scintigraphy and pulmonary angiography(K=0.743, 0.899). Conclusion The MR oxygen-enhanced ventilation combined with pulmonary perfusion imaging can be used to diagnose the airway and vascular abnormity in lung. This technique resembles the ventilation-perfusion scintigraphy. It can provide quantitative functional information and better spatial and temporal resolution, and possesses the value of clinical application.