A new smartphone-linked device developed by
scientists could help assess the effectiveness of muscular dystrophy
medications. The study used a new method to process ultrasound imaging information
that could lead to hand-held instruments that provide fast, convenient medical
In the study presented Oct. 30 at the Acoustical
Society of America's annual meeting, researchers determined how well muscles
damaged by muscular dystrophy responded to a drug in mice with an animal form
of the disease. They did so by processing ultrasound data in a way appropriate
for small, low-power and relatively inexpensive instruments. Called
point-of-care devices, such instruments allow physicians to bring healthcare to
Physicist Michael S. Hughes of the Department of
Energy's Pacific Northwest National Laboratory performed the work with
colleagues John E. McCarthy, Jon N. Marsh, and Samuel A. Wickline while at
Washington University in St. Louis, Missouri.
Although a small study involving animals, it
builds on work in people that shows noninvasive ultrasound can track muscle
health. Duchenne muscular dystrophy -- often shortened to DMD -- affects one
out of 3500 male births. Steroids can help slow muscle degeneration, but too
much medication causes other issues such as weight gain and high blood
"The result implies you can monitor drug
therapy with cheap point-of-care devices," said Hughes. "We'd like to
be able to use low-power handheld instruments, such as a microphone-sized
ultrasound that can fit on a smartphone."
Healthcare workers and patients want fast,
easy-to-use medical instruments and diagnostic tests that they can bring to a
patient's bedside, home or to the field. Some treatments for disease require
constant monitoring, such as blood glucose in people with diabetes or blood
pressure for those with heart disease.
In DMD, muscles fail to repair themselves
adequately, causing the muscles to degenerate over a few decades. Young boys
and men with the disease -- whom DMD hits the most -- usually take steroids to
prolong muscle health. Steroids have serious side effects, so patients should
only take as much as they need, but it's difficult to monitor effectiveness.
Enter ultrasound. Healthy muscle contains neatly
ordered cells, but DMD muscles become fibrous and plum with fat that
infiltrates tissue. Because healthy and sick muscles look different in
ultrasound images, researchers have been exploring how to use ultrasound to
monitor progression of the disease and the muscle's response to drugs.
Previously, researchers, including Hughes,
McCarthy and colleagues, have studied mice with genetic mutations that emulate
muscular dystrophy. Treating mutant mice with steroids, they found they could
process ultrasound information in such a way that they could measure the
difference between healthy, damaged and treated muscles -- a method that could
put out a number on a screen.
But earlier work required more data than small, hand-held ultrasound gadgets,
hooked into a smartphone with a USB cable, would be able to collect. Hughes and
McCarthy wanted to know if they could also distinguish between healthy, sick
and treated muscles if they collected less than 10 percent of the original
data. They turned back to the ultrasound data they had collected on five
healthy mice, four afflicted with mouse muscular dystrophy left untreated, and
four afflicted but treated with steroids for two weeks.
To use less data, they needed to increase the
relevant information in the ultrasound data and downplay the irrelevant
background "noise". To do so, they used a mathematical trick called a
spline, which smooths the data into average values. With a spline added to
their processing program, they re-analyzed either one-eighth or one-sixteenth
of the data.
The team found that even with only one-sixteenth
of the data, they were able to measure the difference between the treated
muscles and the untreated muscles. Of course, people have much larger muscles
than mice do, so the researchers would have to adjust the amount of ultrasound
data to account for that, but Hughes and McCarthy previously showed that is
possible in a different study.
"If we can optimize the processing, we can
increase the sensitivity and provide real-time performance," said Hughes.
"People with muscular dystrophy have to take the least amount of steroid
that will give them the maximum therapeutic effect. This would let them do
This work was supported by the National
Institutes of Health and the National Science Foundation.