With increasing use of high-power laser settings for lithotripsy, the potential exists to induce thermal tissue damage. In vitro studies have demonstrated that temperature elevation sufficient to cause thermal tissue damage can occur with certain laser and irrigation settings. The objective of this pilot study was to measure caliceal fluid temperature during high-power laser lithotripsy in an in vivo porcine model.

The isolation and sorting of cells is an important process in research and hospital labs. Most large research and commercial labs incorporate fluorescently or magnetically labeled antibodies adherent to cell surface antigens for cell identification and separation. In this paper, a process is described that merges biochemical labeling with ultrasound-based separation. Instead of lasers and fluorophore tags, or magnets and magnetic particle tags, the technique uses ultrasound and microbubble tags. Streptavidin-labeled microbubbles were mixed with a human acute lymphoblastic leukemia cell line, CCL 119, conjugated with biotinylated anti-CD7 antibodies. Tagged cells were forced under ultrasound, and their displacement and velocity quantified. Differential displacement in a flow stream was quantified against erythrocytes, which showed almost no displacement under ultrasound. A model for the acoustic radiation force on the conjugated pairs compares favorably with observations. This technology may improve on current time-consuming and costly purification procedures.

Burst wave lithotripsy (BWL) is an experimental method to noninvasively fragment urinary calculi using low-frequency focused bursts of ultrasound. To optimize many of the acoustic parameters for this technology, it is necessary to understand the physical interactions between ultrasound bursts and stones. In this study, the interaction of elastic waves with model stones was simulated and experimentally visualized by photoelastography, a technique using polarized light to spatially and temporally visualize stress patterns.

This study was motivated by the desire to develop a non-invasive means to treat abscesses, and represents the first steps toward that goal. Non-thermal, high-intensity focused ultrasound (HIFU) was used to inactivate Escherichia coli (~1 x 10⁹

In medical and industrial ultrasound, it is often necessary to measure the acoustic properties of a material. A specific medical application requires measurements of sound speed, attenuation, and nonlinearity to characterize livers being evaluated for transplantation. For this application, a transmission-mode caliper device is proposed in which both transmit and receive transducers are directly coupled to a test sample, the propagation distance is measured with an indicator gage, and receive waveforms are recorded for analysis. In this configuration, accurate measurements of nonlinearity present particular challenges: diffraction effects can be considerable while nonlinear distortions over short distances typically remain small. To enable simple estimates of the nonlinearity coeffcient from a quasi-linear approximation to the lossless Burgers’ equation, the calipers utilize a large transmitter and plane waves are measured at distances of 15–50 mm. Waves at 667 kHz and pressures between 0.1 and 1 MPa were generated and measured in water at different distances; the nonlinearity coeffcient of water was estimated from these measurements with a variability of approximately 10%. Ongoing efforts seek to test caliper performance in other media and improve accuracy via additional transducer calibrations.

Comminution of axisymmetric stones by a lithotripter shock wave was studied experimentally and theoretically. In experiments, shock waves were generated by a research electrohydraulic lithotripter modeled after the Dornier HM-3, and stones were made from U-30 cement. Cylindrical stones of various length to diameter ratios, stones of conical shape, and stones with artificial cracks were studied. In other cases, baffles to block specific waves that contribute to spallation or squeezing were used, and glycerol was used to suppress cavitation. The theory was based on the elasticity equations for an isotropic medium. The equations were written in finite differences and integrated numerically. Maximum compression, tensile and shear stresses were predicted depending on the stone shape and side-surface condition in order to investigate the importance of the stone geometry. It is shown that the theoretical model used explains the observed position of a crack in a stone. The theory also predicts the efficiency of stone fragmentation depending on its shape and size, as well as on the presence of cracks on the stone surface and baffles near the stone.