Accuracy evaluation in ultrasonic-based measurement of microscopic change in thickness

Propagation of Vibration Caused by Electrical Excitation in the Normal Human Heart

“…To measure the original wall vibrations of the heart sounds, which are audible by a stethoscope, we have developed a novel ultrasound-based transthoracic method to measure the minute vibrations in the heart wall as waveforms and to show their spatial distribution (Kanai et al 1996(Kanai et al , 1999a(Kanai et al , 1999b. The measurement of the vibration is simultaneously applied to several thousand points preset at 51.3-mm intervals along about 10 ultrasonic beams, which are scanned sparsely in the heart wall to maintain a high frame rate (Kanai et al 2001).…”

Elasticity imaging of atheroma with transcutaneous ultrasound both in longitudinal-axis and short-axis planes

“…The lowest value of the change in thickness was validated as being about 0.5 Am by expanding a rubber plate in a water tank [14]. Such a minute change in thickness cannot be measured by any other method.…”

Measurement of nonlinear property of artery wall using remote cyclic actuation

“…21 Elastic modulus obtained by measuring change in wall thickness From the measured change in wall thickness, the circumferential elastic modulus is obtained as follows: 23 under a two-dimensional stress-strain relationship in the plane that is perpendicular to the axis of the artery, the radial incremental strain, ∆ε r (t), which is defined by dividing the change in thickness, ∆h(t), by the original wall thickness, h 0 , is expressed by the radial and the circumferential incremental stresses, ∆σ r (t) and ∆σ θ (t), as follows: (5) where E r , E θ , and v are the radial and the circumferential elastic moduli and Poisson's ratio, respectively.…”

“…For this purpose, we developed the "phased tracking" method, for measurement of the small change in the thickness of the arterial wall (less than 100 µm) due to the heartbeat. [16][17][18][19][20][21][22][23][24][25][26] From basic experiments, the accuracy of measurement of the change in thickness has been found to be less than 1 µm using the phased tracking method. 17,20,21 From the change in thickness measured by using this method, the regional strain and the elasticity of the arterial wall can be noninvasively evaluated.…”

“…[16][17][18][19][20][21][22][23][24][25][26] From basic experiments, the accuracy of measurement of the change in thickness has been found to be less than 1 µm using the phased tracking method. 17,20,21 From the change in thickness measured by using this method, the regional strain and the elasticity of the arterial wall can be noninvasively evaluated. 23,26 On the basis of the measured elasticity, it should be possible to discriminate tissues in atherosclerotic plaques, such as fibrous tissue and lipids, because of the large differences in their elasticity.…”