Ultrasound imaging of propagation of myocardial contraction for non-invasive identification of myocardial ischemia

Abstract

Non-invasive identification of ischemic regions is important for diagnosis and treatment of myocardial infarction. In the present study, ultrasound measurement was applied to the interventricular septum of three open-chest swine hearts. The properties of the myocardial contraction response of the septum were compared between normal and acute ischemic conditions, where the acute ischemic condition of the septum originated from direct avascularization of the left anterior descending (LAD) coronary artery. The result showed that the contraction response propagated from the basal side to the apical side along the septum. The estimated propagation velocities in the normal and acute ischemic conditions were 3.6 and 1.9 m/s, respectively. This finding indicates that acute ischemia which occurred 5 s after the avascularization of the LAD promptly suppressed the propagation velocity through the ventricular septum to about half the normal velocity. It was suggested that the myocardial ischemic region could be identified using the difference in the propagation velocity of the myocardial response to contraction.

Quantitative evaluation method for liver fibrosis based on multi-Rayleigh model with estimation of number of tissue components in ultrasound B-mode image

“…It can be assumed that the power of the echo envelope from the normal tissue does not change in the near-field region; therefore, if we could determine the power of the echo envelope from the normal tissue in the near-field region for reference, the composition of two components of tissue could be determined by comparing the reference power of the echo envelope from the normal tissue with power of each tissue, ð RA 1 Þ 2 and ð RA 2 Þ 2 , in the MRA model with two components. In this paper, the estimated power of the echo envelope, (σ RA ) 2 , where the window is composed of one component of tissue and the estimated power ð RA 2 Þ 2 , where the window is composed of three-components of tissue, were used as the reference powers of the echo envelope from the normal tissue.…”

“…When the target window is composed of one component of tissue, the power of the echo envelope in the window can be calculated as (σ RA ) 2 …”

“…where x is the echo envelope amplitude corresponding to the intensity of each pixel in the B-mode image and σ RA is a scale parameter estimated as (σ RA ) 2 …”

“…Step 3 Calculate the squared Mahalanobis distance (D data ) 2 using Eq. (7), where V = V data , " ¼ " RA , and Σ = Σ RA .…”

“…[1][2][3][4] The development of a quantitative diagnostic method for liver fibrosis using an ultrasound B-mode image is highly required because it is not easy to quantitatively evaluate the progression of liver fibrosis only from the Bmode image. In a previous study, the acoustical properties of liver tissues were measured to realize the characteristics of such tissues.…”