Doctors can now get a peek behind the eardrum to better
diagnose and treat chronic ear infections, thanks to a new medical imaging
device invented by University
of Illinois researchers.
The device could usher in a new suite of noninvasive, 3D diagnostic imaging
tools for primary-care physicians.
The research team, led by University of Illinois
electrical and computer engineering professor Stephen Boppart, will publish
their advance in an online Early Edition of the Proceedings of the National Academy of Sciences.
Ear infections are the most common conditions that
pediatricians treat. Chronic ear infections can damage hearing and often
require surgery to place drainage tubes in the eardrum, and problems can
persist into adulthood.
Studies have found that patients who suffer from chronic ear
infections may have a film of bacteria or other microorganisms that builds up
behind the eardrum, very similar to dental plaque on unbrushed teeth. Finding
and monitoring these so-called biofilms are important for successfully
identifying and treating chronic ear infections.
“We know that antibiotics don’t always work well if you have
a biofilm, because the bacteria protect themselves and become resistant,”
Boppart said. “In the presence of a chronic ear infection that has a biofilm,
the bacteria may not respond to the usual antibiotics, and you need to stop
them. But without being able to detect the biofilm, we have no idea whether or
not it’s responding to treatment.”
However, middle-ear biofilms are difficult to diagnose. A
doctor looking through a standard otoscope sees only the eardrum’s surface, not
the bacteria-seeded biofilm lurking behind it waiting to bloom into infection.
Invasive tests can provide evidence of a biofilm, but are unpleasant for the
patient and cannot be used routinely.
The new device is an application of a technique called
optical coherence tomography (OCT), a noninvasive imaging system devised by
Boppart’s group. It uses beams of light to collect high-resolution, 3D tissue images, scanning through the eardrum to the biofilm
behind it—much like ultrasound imaging, but using light.
“We send the light into the ear canal, and it scatters and
reflects from the tympanic membrane and the biofilm behind it,” said graduate
student Cac Nguyen, the lead author of the paper. “We measure the reflection,
and with the reference light we can get the structure in depth.”
The single scan is performed in a fraction of a second—speed
is a necessity for treating squirming tots—and images a few millimeters deep
behind the eardrum. Thus, doctors can see not only the presence of a biofilm,
but also how thick it is and its position against the eardrum.
The paper marks the first demonstration of using the ear OCT
device to detect biofilms in human patients. To test their device, the
researchers worked with clinicians at Carle
in Urbana, Ill., to scan patients with diagnosed
chronic ear infections, as well as patients with normal ears. The device
identified biofilms in all patients with chronic infections, while none of the
normal ears showed evidence of biofilms.
“I think this is now a technology that allows physicians to
monitor chronic ear infection, and examine better ways to treat the disease,”
said Boppart, who is also affiliated with the departments of bioengineering and
internal medicine, the Institute for Genomic Biology, and the Beckman Institute
for Advanced Science and Technology at the U. of I. “We can use different antibiotics and see how the biofilm responds.”
Next, the researchers plan to investigate different ear
pathology, particularly comparing acute and chronic infections, and will
examine the relationship between biofilms and hearing loss. They hope that
improved diagnostics will lead to better treatment and referral practices.
The researchers hope to make their device—currently a handheld
prototype—even more compact, easy to use, and low-cost. The device company
Welch Allyn, based in Skaneateles
Falls, N.Y., is a
collaborator on the project, which was funded by the National Institutes of
Boppart’s group and its collaborators also will work to
apply OCT imaging to other areas commonly examined by primary-care physicians.
The ear-imaging device is the first in a suite of OCT-based imaging tools that
the group plans to develop. Doctors could change the tip of the new OCT device,
for example, to look at the eyes, mouth, nose, or skin.
“All the sites that a primary-care physician would look at,
we can now look at with this more advanced imaging,” Boppart said. “With OCT,
we are bringing to the primary-care clinic high-resolution 3D digital imaging
and being able to look at many different tissue structures in real-time,
non-invasively and in depth.”
“As medicine gets more high-tech, we want to give the
front-line doctor the best technology to detect disease early,” Boppart said.