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Micrometer-sized microcapsules collapse upon exposure to ultrasound. Use of this phenomenon for a drug delivery system (DDS), not only for local delivery of medication but also for gene therapy, should be possible. However, enhancing the efficiency of medication is limited because capsules in suspension diffuse in the human body after injection, since the motion of capsules in blood flow cannot be...
We describe the first mapping of biological current in a live heart using ultrasound current source density imaging (UCSDI). Ablation procedures that treat severe heart arrhythmias require detailed maps of the cardiac activation wave. UCSDI can potentially improve on existing mapping procedures which are time-consuming and limited by its poor spatial resolution (5-10 mm). UCSDI is based on a pressure-induced...
Ultrasound strain imaging has been proposed to quantitatively assess myocardial contractility. Cross-correlation based 2D speckle tracking (ST) and auto-correlation based Doppler tissue imaging (DTI) are competitive ultrasound techniques for this application. Unlike ST, DTI is limited by angle dependency and suffers from low signal-to-noise ratio because a high pulse repetition frequency (PRF) is...
Cardiac motion related artifact in ultrasound induced thermal strain imaging (TSI) was reduced in-vitro and in-vivo using ECG gating. Tissue motion due to the heart beat is a major challenge for in-vivo TSI application, especially for cardiovascular systems. Temporal variation of the relative position between the transducer and the artery will induce decorrelation in speckle tracking. Tissue deformation...
Tissue engineers are greatly interested in non- invasively evaluating the extent of cell growth, scaffold degradation, and tissue development both in vitro and in vivo as a function of time. Current evaluation methods such as cell histology and direct mechanical measurements can only provide static snapshots using different specimens at different time points. These measurements introduce specimen...
The feasibility of inducing and imaging thermal strain to identify vulnerable plaques in peripheral arteries based on conventional ultrasound scanners is demonstrated. Vulnerable plaque usually consists of a large lipid-rich core. Because lipid-bearing tissue has a negative temperature dependence of sound speed, whereas water-based tissue has a positive one, thermal strain imaging can differentiate...
An optimized elastic modulus reconstruction procedure from ultrasound strain and pulse wave velocity (PWV) measurements was validated using a commercial ultrasound scanner. Longitudinal and transverse scans were performed on a vessel phantom connected to a pulsatile pump. Time delay between the ultrasound beams at each side of the transducer determines PWV and transverse elasticity imaging estimates...
Strain rate imaging has been proposed to quantitatively evaluate myocardial deformation and potentially quantify injury of ischemic heart disease (IHD) and remodeling of myocardial infarction (MI). However, because deformation of the cardiac wall is complex and three-dimensional, it's hard to evaluate imaging algorithms (e.g., 2D/3D speckle tracking for strain rate estimation) without a well-controlled...
Minimally invasive electrophysiology interventions to treat cardiac arrhythmias are increasing worldwide due to advances in technologies that enable more effective clinical procedures. A forward imaging ultrasound catheter design has been developed and tested to advance the methods of integration of intracardiac imaging and electrophysiology sensing. The first catheters built have been constructed...
The etiology of skeletal muscle fatigue is not well understood partly because techniques portraying muscle performance in vivo are limited by either their invasiveness (e.g., needle electrodes) or poor spatial resolution (e.g., surface EMG). To better characterize effects of FES and muscle fatigue, we captured real-time high resolution dynamics of the human forearm before and after a fatigue exercise...
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