Development of Functional Ultrasonic Contrast Agent

本研究取得的主要成果如下：1.研制了一种可受外加磁场控制、比重随周围流体密度可调的超声造影剂。该药剂由中空双层球体组成。研制了谐振式超声示踪器，阐明了空心磁性微球的共振频率与直径之间的关系。利用该示踪剂对慢速流体流动进行了可视化演示。提出了一种利用图像序列进行二维场检测和计算的新方法。这种计算模型有一个多通道运动检测器。实验结果表明，与单通道模型相比，该模型能够检测到更可靠的运动场。将该方法应用于血流检测。

Main results obtained in this research are as follows ;1. An ultrasonic contrast agent which can be controlled by an external magnetic field, and whose specific gravity is adjustable to that of the ambient fluid is developed. The agent is made of hollow two-layred spheres.2. A resonant type ultrasonic tracer is developed and the relation between the resonance frequency and the diameter of hollow magnetic micro spheres is clarfied. Flow visualization of slow fluid flow was demonstrated using this tracers.3. A new approach for the detection and computation of two dimensional field using image sequence is presented. This computational model has a multi-channel motion detector. Experimental results shows that this model detects more reliable motion fields compared to one-channel model.3. The approach was applied for the detection of blood flow.