Space researchers develop ultrasound technology that detects, treats kidney stones

HOUSTON
– Just the mention of kidney stones can cause a person to cringe. They are
often painful and sometimes difficult to remove, and 10 percent of the
population will suffer from them. In space, the risk of developing kidney
stones is exacerbated due to environmental conditions. The health risk is
compounded by the fact that resource limitations and distance from Earth could
restrict treatment options.

Scientists with the National Space
Biomedical Research Institute (NSBRI) are developing an ultrasound
technology that could overcome some medical care challenges associated with
kidney stone treatment. The new technology detects stones with advanced ultrasound
imaging based on a process called “Twinkling Artifact” and provides
treatment by “pushing” the stone with focused ultrasound. This
technology could not only be beneficial for health care in space, but could
also alter the treatment of kidney stones on Earth.

The project is led by NSBRI Smart
Medical Systems and Technology Team Principal Investigator Dr. Lawrence
Crum and Co-Investigator Dr. Michael Bailey; both are researchers at the Applied Physics Laboratory
at the University of Washington (APL-UW). Bailey said their technology is based
on equipment currently available.

“We have a diagnostic ultrasound machine that has
enhanced capability to image kidney stones in the body,” said Bailey, a
principal engineer at APL-UW. “We also have a capability that uses
ultrasound waves coming right through the skin to push small stones or pieces
of stones toward the exit of the kidney, so they will naturally pass, avoiding
surgery.”

Currently on Earth, the preferred removal method is for
patients to drink water to encourage the stones to pass naturally, but this
does not always work, and surgery is often the only option. In space, the
threat from kidney stones is greater due to the difficulty of keeping astronauts
fully hydrated. Another factor is that bones demineralize in the
reduced-gravity environment of space, dumping salts into the blood and
eventually into the urine. The elevated concentration of salts in the urine is
a risk factor for stones.

Crum, who is a principal physicist at APL-UW, said kidney
stones could be a serious problem on a long-duration mission. “It is
possible that if a human were in a space exploration environment and could not
easily return to Earth, such as a mission to an asteroid or Mars, kidney stones
could be a dangerous situation,” Crum said. “We want to prepare for
this risk by having a readily available treatment, such as pushing the stone
via ultrasound.”

Before a stone can be pushed, it needs to be located.
Standard ultrasound machines have a black and white imaging mode called B-mode
that creates a picture of the anatomy. They also have a Doppler mode that
specifically displays blood flow and the motion of the blood within tissue in
color. In Doppler mode a kidney stone can appear brightly colored and
twinkling. The reason for this is unknown, but Crum and Bailey are working to
understand what causes the Twinkling Artifact image.

“At the same time, we have gone beyond Twinkling
Artifact and utilized what we know with some other knowledge about kidney
stones to create specific modes for kidney stones,” Bailey said. “We
present the stone in a way that looks like it is twinkling in an image in which
the anatomy is black and white, with one brightly colored stone or multiple colored
stones.”

Once the stones are located, the ultrasound machine operator
can select a stone to target, and then, with a simple push of a button, send a
focused ultrasound wave, about half a millimeter in width, to move the stone
toward the kidney’s exit. The stone moves about one centimeter per second. In
addition to being an option to surgery, the technology can be used to
“clean up” after surgery.

“There are always residual fragments left behind after
surgery,” Bailey said. “Fifty percent of those patients will be back
within five years for treatment. We can help those fragments pass.”

The ultrasound technology being developed for NSBRI by Crum
and Bailey is not limited to kidney stone detection and removal. The technology
can also be used to stop internal bleeding and ablate (or destroy) tumors. Crum
said the research group has innovative plans for the technology. “We
envision a platform technology that has open architecture, is software-based
and can use ultrasound for a variety of applications,” he said. “Not
just for diagnosis, but also for therapy.”

NSBRI’s research portfolio includes other projects seeking
to develop smart medical systems and technologies, such as new uses for
ultrasound, that provide health care to astronauts in space. Crum, who served
eight years as an NSBRI Team Leader, said the innovative approaches to overcome
the restrictive environment of space can make an impact on Earth.

“Space has demanded medical care technology that is
versatile, low-cost and has restricted size. All of these required
specifications for use in a space environment are now almost demanded by the
general public,” Crum said. “One of the reasons that translation from
one site to another is possible is because of NSBRI’s investment.”

The ultrasound work by Crum and Bailey has also received
support from the Defense Advance Research Projects Agency, the National
Institutes of Health, and the University
of Washington and
foundations associated with it to promote commercialization.

NSBRI is a NASA-funded consortium of institutions
studying the health risks related to long-duration spaceflight and developing
the medical technologies needed for long missions. NSBRI is headquartered at
Baylor College of Medicine in Houston, with its
science, technology and education projects taking place at more than 60
institutions across the United
States. In addition to protecting astronaut
health, NSBRI research has benefits for health care on Earth. For more
information about NSBRI, please visit www.nsbri.org.

Posted
by Sean Fenske, Editor-in-Chief, MDT