Adam D Maxwell 2024: vealing physical interactions of ultrasound waves with the body through photoelasticity imaging

Thursday, 14 November 2024

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Adam D Maxwell 1 2
1Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061.
2Department of Urology, University of Washington School of Medicine, Seattle, WA 98195.

Abstract

Ultrasound is a ubiquitous technology in medicine for screening, diagnosis, and treatment of disease. The functionality and efficacy of different ultrasound modes relies strongly on our understanding of the physical interactions between ultrasound waves and biological tissue structures. This article reviews the use of photoelasticity imaging for investigating ultrasound fields and interactions. Physical interactions are described for different ultrasound technologies, including those using linear and nonlinear ultrasound waves, as well as shock waves. The use of optical modulation of light by ultrasound is presented for shadowgraphic and photoelastic techniques. Investigations into shock wave and burst wave lithotripsy using photoelastic methods are summarized, along with other endoscopic forms of lithotripsy. Photoelasticity in soft tissue surrogate materials is reviewed, and its deployment in investigating tissue-bubble interactions, generated ultrasound waves, and traumatic brain injury, are discussed. With the continued growth of medical ultrasound, photoelasticity imaging can play a role in elucidating the physical mechanisms leading to useful bioeffects of ultrasound for imaging and therapy.

Opt Lasers Eng. 2024 Oct:181:108361. doi: 10.1016/j.optlaseng.2024.108361. Epub 2024 Jun 14.
PMID: 39219742 PMCID: PMC11361005 (available on 2025-10-01)

Comments 1

Othmar Wess on Thursday, 14 November 2024 10:00

To date, ultrasound and shock waves are indispensable tools for a multitude of diagnostic and therapeutic medical procedures. The working mechanism for stimulation and fragmentation of body stones is still under discussion. A hindrance is that both waves are not visible for the naked eye and their spatiotemporal working zone in the body is difficult to monitor. The author Adam D Maxwell provides an overview over available optical methods to visualize spatial ultrasound and shock wave fields.
As ultrasound and shock waves are pressure waves, they cause pressure generated density fluctuations in water, traveling with a velocity of app, 1500m/s. They retard and/or refract light waves at that position which are visualized by optical arrangements such as shadowgraph or schlieren optics.
We can optically visualize the waves in water but usually not in optically dense biological tissue.
The interaction of ultrasound waves with the body through photoelasticity imaging, as stated in the title, is limited to model experiments.
Photoelasticity imaging requires special tissue surrogate materials to visualize
stress-induced birefringence. Complex tissue structures as muscles, tendons and bones etc., however, are difficult to mimic by optically transparent materials.
Simple structures such as cubes or cylinders may give an impression of what happens with ultrasound in soft and solid tissues.
We include 3 samples of images taken with a colour schlieren optical set up in our lab.
1. Focused shockwave in water including growing and collapsing cavitation bubbles in the tail of the shock wave. (Schlieren optic)
2. Shockwave field in an acrylic cube (Schlieren optic combined with photoelasticity imaging)
3. Shockwave field in an acrylic cylinder (Schlieren optic combined with photoelasticity imaging)

Othmar Wess

To date, ultrasound and shock waves are indispensable tools for a multitude of diagnostic and therapeutic medical procedures. The working mechanism for stimulation and fragmentation of body stones is still under discussion. A hindrance is that both waves are not visible for the naked eye and their spatiotemporal working zone in the body is difficult to monitor. The author Adam D Maxwell provides an overview over available optical methods to visualize spatial ultrasound and shock wave fields. 
As ultrasound and shock waves are pressure waves, they cause pressure generated density fluctuations in water, traveling with a velocity of app, 1500m/s. They retard and/or refract light waves at that position which are visualized by optical arrangements such as shadowgraph or schlieren optics.
We can optically visualize the waves in water but usually not in optically dense biological tissue.
The interaction of ultrasound waves with the body through photoelasticity imaging, as stated in the title, is limited to model experiments. 
Photoelasticity imaging requires special tissue surrogate materials to visualize 
stress-induced birefringence. Complex tissue structures as muscles, tendons and bones etc., however, are difficult to mimic by optically transparent materials. 
Simple structures such as cubes or cylinders may give an impression of what happens with ultrasound in soft and solid tissues.
We include 3 samples of images taken with a colour schlieren optical set up in our lab. 
1. Focused shockwave in water including growing and collapsing cavitation bubbles in the tail of the shock wave. (Schlieren optic)
2. Shockwave field in an acrylic cube (Schlieren optic combined with photoelasticity imaging)
3. Shockwave field in an acrylic cylinder (Schlieren optic combined with photoelasticity imaging)

[img]https://www.storzmedical.com/images/blog/Maxwell1.PNG[/img]
[img]https://www.storzmedical.com/images/blog/Maxwell2.PNG[/img]
[img]https://www.storzmedical.com/images/blog/Maxwell3.PNG[/img]

Othmar Wess

To date, ultrasound and shock waves are indispensable tools for a multitude of diagnostic and therapeutic medical procedures. The working mechanism for stimulation and fragmentation of body stones is still under discussion. A hindrance is that both waves are not visible for the naked eye and their spatiotemporal working zone in the body is difficult to monitor. The author Adam D Maxwell provides an overview over available optical methods to visualize spatial ultrasound and shock wave fields. As ultrasound and shock waves are pressure waves, they cause pressure generated density fluctuations in water, traveling with a velocity of app, 1500m/s. They retard and/or refract light waves at that position which are visualized by optical arrangements such as shadowgraph or schlieren optics. We can optically visualize the waves in water but usually not in optically dense biological tissue. The interaction of ultrasound waves with the body through photoelasticity imaging, as stated in the title, is limited to model experiments. Photoelasticity imaging requires special tissue surrogate materials to visualize stress-induced birefringence. Complex tissue structures as muscles, tendons and bones etc., however, are difficult to mimic by optically transparent materials. Simple structures such as cubes or cylinders may give an impression of what happens with ultrasound in soft and solid tissues. We include 3 samples of images taken with a colour schlieren optical set up in our lab. 1. Focused shockwave in water including growing and collapsing cavitation bubbles in the tail of the shock wave. (Schlieren optic) 2. Shockwave field in an acrylic cube (Schlieren optic combined with photoelasticity imaging) 3. Shockwave field in an acrylic cylinder (Schlieren optic combined with photoelasticity imaging) [img]https://www.storzmedical.com/images/blog/Maxwell1.PNG[/img] [img]https://www.storzmedical.com/images/blog/Maxwell2.PNG[/img] [img]https://www.storzmedical.com/images/blog/Maxwell3.PNG[/img] Othmar Wess

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