Researchers

Tom Matula

Senior Principal Physicist

CIMU Department

APL-UW

Affiliate Assistant Professor, Bioengineering and Affiliate Associate Professor, Electrical Engineering

Hong Chen

Postdoctoral Research Scientist, Biomedical Engineering

Columbia University

Andrew Brayman

Principal Physicist

CIMU Department

APL-UW

Rusty Starr

Research Manager

CIMU Department

APL-UW

Acknowledgments

Mike Bailey

Senior Principal Engineer

CIMU Department

APL-UW

Assistant Professor, Mechanical Engineering and Adjunct Assistant Professor, Urology

Larry Crum

Principal Physicist

CIMU Department

APL-UW

Research Professor, Electrical Engineering and Bioengineering

Wayne Kreider

Senior Engineer

CIMU Department

APL-UW

Funding

NIH NIBIB

Ultrasound Contrast Agents (Microbubbles) in the Microvasculature

Center for Industrial and Medical Ultrasound

What are we doing?

Why are we doing it?

High-speed images of oscillating micro-bubbles in small blood vessels are imaged to observe how the bubble oscillations might help induce permeation in the endothelium, allowing drugs to be transported across that barrier.

Drugs and genes can be delivered locally using focused ultrasound. This can significantly improve uptake of molecules economically. Knowing just how these bubbles can open the endothelium barrier is thus important.

How are we doing it?

Specifics

We excise the mesentery, immerse it in a Krebs solution and place it on a microscope. A flash lamp is used to deliver enough light to obtain good images with 50 nsec exposure times. Microbubbles are perfused along with a saline solution. When a vessel is found containing microbubbles, the experiment is triggered, sending a very short ultrasound pulse (1 MHz) towards the tissue sample. 14 images are collected at pre-determined times (usually every 150 or 300 nsec). Quantification of the images gives us information about vessel deformations, bubble oscillations, and registration of the specific locations that are later used to correlate vessel motion with histological observations of vessel damage.

The experimental setup and timing diagram are illustrated in the following figure:

Two important notes

Vessel size: 22 µm
Pressure amplitude: 1.8 MPa

  1. Acoustic pulses come from out of the page. The observed microbubble and microvessel motions are orthogonal to the acoustic directions. Thus, the effects are NOT due to acoustic radiation force.
  2. Image sequences are taken on sub-microsecond timescales. Vessel response is forced, it is not an evoked response.

© 2011–2013 University of Washington

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