Visceral fat inspection method based on the ultrasound tomographic reconstruction of abdominal tissue sound speed image

本研究基于对人体腹部周围超声飞行时间数据的观测，对实现超声层析内脏脂肪检查仪进行了研究和验证实验。特别研制了一种采用面向一对低频高灵敏度宽带压电换能器的机械扫描系统，可以检测到通过远距离肠道气体介质传播的波而不受声音衰减的影响。此外，在换能器前附着聚氨酯凝胶半球，使换能器与体表保持良好的接触，无论两者之间的接触角度如何。连接在自动执行器台上的面对换能器用于旋转（直径720 mm），平移（600 mm行程）和推动（300 mm行程）的运动，由计算机控制移动到腹部体表的任意位置。为了尽量减少由于避免声音传播路径与脊柱相交而造成的数据损失，我们确定了传播路径，将扫描旋转的中心调整到脊柱。为此，利用激光测距传感器测量体表轮廓，并对脊柱位置进行预估。通过这种方法，可以根据患者的体型和坐姿自适应地确定路径。此外，还监测了声波的振幅，以便在不考虑预先测量的体表位置偏差的情况下，将接触条件控制在最佳推送位置。最后，利用模拟标本进行了评价实验，结果表明，飞行时间数据的测量精度足以再现腹部声速横截面图像。此外，从结果中证实了所提出的内脏脂肪测量技术的有效性，脂肪区域可以清晰地与剩余的蛋白质区域区分开来，准确度很高。虽然对人体患者的评估实验仍有待进一步的工作，但该系统已经完成，可以自动收集体表周围的声波数据，并从腹部重构声速图像中测量内脏脂肪面积。少

In the present study, investigations and validation experiments were made for the realization of acoustic tomographic visceral fat inspection apparatus based on the observation of ultrasound time of flight data around human abdominal surface. In particular, mechanical scanning system using a facing pair of high sensitivity broad band piezoelectric transducers in low frequency range was developed, so that waves propagated through the long distant intestinal gaseous medium can be detected without suffering sound attenuation. In addition, urethane gel hemi-spheres were attached in front of the transducers to keep good contact between transducer and body surface, regardless of contact angles between them. The facing pair transducers attached on the automated actuator stages for the movement of rotation (720 mm in diameter), translation (600 mm stroke), and pushing (300 mm stroke) were controlled by the computers to move to arbitral positions on the abdominal body surface. On this occasion, … More to minimize the loss of data caused by the avoidance of sound propagation paths intersecting a spine, propagation path was determined so that center of scanning rotation was adjusted to the spine. To this end, contour of the body surface was measured by laser range sensor and spine position was estimated in advance. By this means, the paths were adaptively determined in accordance with patient’s body size and sitting position. In addition, amplitudes of the sound waves were monitored so that contact condition can be controlled at an optimalpushing position regardless of the deviation of the premeasured body surface position. Finally, from the evaluation experiments by using the phantom specimen, it was shown that the measured precision of time of flight data were good enough to reproduce the abdominal sound speed cross sectional profile image. In addition, validity of the proposed visceral fat measurement techniques was confirmed from the results that fat areas can be clearly discriminated from the remaining protein areas with high degree of accuracy. Although the evaluation experiments for human patients were remained as future work, the system was brought to completion which can automatically collect the sound wave data around body surface andmeasure the visceral fat area from the abdominal reconstructed sound speed image. Less