Showing papers by "Scott D. Swanson published in 1998"
TL;DR: A physical and mathematical basis of SWEI is presented and some experimental results of pilot studies proving feasibility of this new ultrasonic technology are presented, including a theoretical model of shear oscillations in soft biological tissue remotely induced by the radiation force of focused ultrasound.
Abstract: Shear wave elasticity imaging (SWEI) is a new approach to imaging and characterizing tissue structures based on the use of shear acoustic waves remotely induced by the radiation force of a focused ultrasonic beam. SWEI provides the physician with a virtual "finger" to probe the elasticity of the internal regions of the body. In SWEI, compared to other approaches in elasticity imaging, the induced strain in the tissue can be highly localized, because the remotely induced shear waves are attenuated fully within a very limited area of tissue in the vicinity of the focal point of a focused ultrasound beam. SWEI may add a new quality to conventional ultrasonic imaging or magnetic resonance imaging. Adding shear elasticity data ("palpation information") by superimposing color-coded elasticity data over ultrasonic or magnetic resonance images may enable better differentiation of tissues and further enhance diagnosis. This article presents a physical and mathematical basis of SWEI with some experimental results of pilot studies proving feasibility of this new ultrasonic technology. A theoretical model of shear oscillations in soft biological tissue remotely induced by the radiation force of focused ultrasound is described. Experimental studies based on optical and magnetic resonance imaging detection of these shear waves are presented. Recorded spatial and temporal profiles of propagating shear waves fully confirm the results of mathematical modeling. Finally, the safety of the SWEI method is discussed, and it is shown that typical ultrasonic exposure of SWEI is significantly below the threshold of damaging effects of focused ultrasound.
1,632 citations
TL;DR: The magnetic coupling between methyl lactate protons and water protons in samples of cross-linked bovine serum albumin (BSA) is studied and cross-relaxation spectroscopy shows efficient magnetization transfer from immobilized BSA to both water and methyl lactates protons.
33 citations
11 Jan 1998-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, the authors investigated the feasibility of magnetic resonance imaging with laser-polarized 129 Xe and concluded that by increasing the production and absolute polarization of the129 Xe, it will be possible to apply this technique to human brain activation studies based on quantitative measurement of regional cerebral blood flow.
Abstract: To investigate the feasibility of magnetic resonance imaging with laser-polarized 129 Xe we have undertaken the study of time dependences of the 129 Xe magnetization in the whole body and its build-up in the brain. We conclude that by increasing the production and absolute polarization of the 129 Xe, it will be possible to apply this technique to human brain activation studies based on quantitative measurement of regional cerebral blood flow.
19 citations
20 Jan 1998
TL;DR: This work establishes that nuclear polarization produced in the gas phases survives transport to the brain where it may be imaged in 129Xe and will allow clinical measurements of regional blood flow.
Abstract: Magnetic Resonance Imaging with laser-polarized 129Xe can be utilized to trace blood flow and perfusion in tissue for a variety of biomedical applications. Polarized xenon gas introduced in to the lungs dissolves in the blood and is transported to organs such as the brain where it accumulates in the tissue. Spectroscopic studies combined with imaging have been used to produce brain images of 129Xe in the rat head. This work establishes that nuclear polarization produced in the gas phases survives transport to the brain where it may be imaged. Increases in polarization and delivered volume of 129Xe will allow clinical measurements of regional blood flow.
7 citations