Evaluation of thrombolysis by using ultrasonic imaging: an in vitro study

Abstract

The hematocrit of a thrombus is a key factor associated with the susceptibility to thrombolysis. Ultrasonic imaging is currently the first-line screening tool for thrombus examinations. Different hematocrits result in different acoustical structures of thrombi, which alter the behavior of ultrasonic backscattering. This study explored the relationships among thrombolytic efficiencies, hematocrits, and ultrasonic parameters (the echo intensity and backscattered statistics). Porcine thrombi with different hematocrits, ranging from 0% to 50%, were induced in vitro. An ultrasonic scanner was used to scan thrombi and acquire raw image data for B-mode (echo intensity measurements) and Nakagami imaging (backscattered statistics analysis). Experiments on thrombolysis were performed using urokinase to explore the effect of the hematocrit on thrombolytic efficiency. Results showed that the weight loss ratio of thrombi exponentially decreased as the hematocrit increased from 0% to 50%. Compared with the echo intensity obtained from the conventional B-scan, the Nakagami parameter predicts the weight loss ratio, increasing from 0.6 to 1.2 as the weight loss ratio decreased from 0.67 to 0.26. The current findings suggest that using Nakagami imaging characterizing thrombi provides information of backscattered statistics, which may be associated with the thrombolytic efficiency.

Acoustic structure quantification by using ultrasound Nakagami imaging for assessing liver fibrosis

“…The detailed techniques of Nakagami parameter estimation and imaging were described previously 14 28 29 . In brief, (i) The envelope image was obtained using the absolute value of the Hilbert Transform of each echo signal filtered using empirical mode decomposition 28 ; (ii) A square window within the envelope image was used to collect local amplitude data for estimating the Nakagami parameter, which is assigned as the new pixel located in the center of the window.…”

“…In brief, (i) The envelope image was obtained using the absolute value of the Hilbert Transform of each echo signal filtered using empirical mode decomposition 28 ; (ii) A square window within the envelope image was used to collect local amplitude data for estimating the Nakagami parameter, which is assigned as the new pixel located in the center of the window. The side length of the window was three times the pulse length of the transducer 14 24 25 27 29 . The maximum likelihood estimator (MLE) derived by Greenwood 30 was selected to calculate the Nakagami parameter because MLE yields a lower variance in estimating the Nakagami parameter 31 32 33 .…”

Control of fibrinolytic drug injection via real-time ultrasonic monitoring of blood coagulation

“…Certainly, further in vivo investigations are required to answer a general question: whether the monitoring of the early stages of blood coagulation can increase the real clinical facilities for the prevention of thrombotic complications. Until recently, practically all research on the ultrasonic registration of blood coagulation has been carried out with in vitro model systems [7–18, 23–25, 53]. A few novel studies in this research field that have employed in vivo experiments have been published just recently [20–22].…”

Retrieved cerebral thrombi studied by T 2 and ADC mapping: preliminary results

“…A fibrin meshwork by itself is a permeable porous structure; however, its permeability may be strongly influenced by the presence of platelets as well as of fibrin cross-linking which could considerably thicken the meshwork 6, 7. Entrapped RBCs in thrombi8 reduce pore sizes within the meshwork and therefore also reduce the permeability of the thrombi 9. Furthermore, distribution and proportion of the entrapped blood cells in thrombi (RBCs and platelets) influence their mechanical properties as well 10.…”