Ultrasound
images, known as sonograms, have become a familiar part of pregnancy, allowing
expectant parents a view of their unborn child. But new research at Massachusetts
Institute of Technology (MIT) could improve the ability of untrained workers to
perform basic ultrasound tests, while allowing trained workers to much more
accurately track the development of medical conditions, such as the growth of a
tumor or the buildup of plaque in arteries.
The
improvements to this widely used technology could provide detailed information
far beyond what is possible with existing systems, the researchers say. The
work, led by Brian W. Anthony, co-director of MIT’s Medical Electronic Device
Realization Center (MEDRC) and director of the Master of Engineering in
Manufacturing Program, was recently presented at the International Symposium on
Biomedical Imaging in Barcelona,
Spain.
There
are two key elements to the improvements engineered by Anthony and his team.
First, the researchers devised a way to adjust for variations in the force
exerted by a sonographer, producing more consistent images that can compensate
for body motions such as breathing and heartbeat. Second, they provided a way
to map the exact location on the skin where one reading was taken, so that it
can be precisely matched with later readings to detect changes in the size or
location of a tumor, clot, or other structure.
Together,
the two improvements could make sonography a much more precise tool for
monitoring the progression of disease, Anthony says. The devices are currently
undergoing three clinical trials, including one at Boston Children’s Hospital
focused on monitoring the progression of patients with Duchenne Muscular
Dystrophy (DMD).
In
that trial, Anthony says, researchers are trying to determine “how fast the
muscle deteriorates, and how effective different medications are.” It’s
important to have a reliable way of monitoring changes in muscle, he says. The
study is aimed at determining whether ultrasound analysis can serve as a
convenient, noninvasive, clinically meaningful way of monitoring disease
progression in DMD.
The
new device maintains constant force through the addition of a force sensor to
its probe tip and servomotors that can respond almost instantly to changes in
force. That, in turn, makes it possible to analyze how the image varies as the
force increases, which can provide important diagnostic information about the
elasticity of skin, muscle, and other tissues.
To
provide accurate positioning, a tiny camera and lens mounted on the probe can
reveal skin patterns that are distinctive and constant, similar to
fingerprints. “Skin patterns are pretty unique,” Anthony says; his team’s
system, using software to compare new images with earlier ones, “can get you
back to that same patch of skin,” something that is impossible to do manually.
Anthony
likens that precise positioning to “an on-the-patient GPS system” for locating
structures in the body. The ability to take images over time from exactly the
same position makes it possible to monitor changing tissues quite precisely:
The imaging system can determine the volume of a near-surface tumor or other
feature to within an accuracy of 1% to 2%, he says. There are existing ways to
get this kind of accuracy, but these require expensive specialized equipment
that few hospitals have.
Besides
the potential for these advanced diagnostic capabilities, enhanced control over
testing could make it possible for relatively untrained health care workers to
administer basic ultrasound pregnancy tests—especially in remote, underserved
areas where trained sonographers may not be available. The various control
techniques “take the uncertainty out” of the process, Anthony says.
Craig
Steiner, an anesthesiologist at Chester
County Hospital
in Pennsylvania,
says, “I’m excited about the prospects” of these improved systems. “The
reproducibility of the scan with consistent pressure and picture quality would
help with remote readings of locally done scans. This could be relevant for
teleradiology, which is an area ripe for expansion.”
Steiner
adds: “The field of ultrasound is still developing. Ultrasound will partially
replace CT scans, reduce radiation exposure to patients and make diagnosing
easier when away from the high-cost hospitals. It can help our world provide
care at a more reasonable cost with a new paradigm of care.”
