OCT Device Could KO Ear Infections

A new optical coherence tomography (OCT) device that can see difficult-to-detect bacteria behind the eardrum could help clinicians to better diagnose and treat chronic ear infections.

Ear infections are the most common conditions that pediatricians treat. Chronic ear infections can be detrimental to hearing and often require surgery to place drainage tubes in the eardrums. Patients who suffer from chronic ear infections may have a film of bacteria or other microorganisms that build up behind the eardrum, according to studies. To treat such infections, these biofilms must be detected and monitored.

“We know that antibiotics don’t always work well if you have a biofilm, because the bacteria protect themselves and become resistant,” said Stephen Boppart, a University of Illinois electrical and computer engineering professor. “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.”

University of Illinois researchers tested a prototype of a new device that can see biofilms behind the eardrum to better diagnose and treat chronic ear infections. (Image: Stephen Boppart)

Middle-ear biofilms are difficult to diagnose, and current invasive tests to see evidence of biofilms are unpleasant for the patient and cannot be used routinely.

Now, Boppart and his research team have devised a noninvasive imaging system that uses beams of light to collect high-resolution, three-dimensional 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 Cac Nguyen, a graduate student and 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 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.

This marks the first demonstration of an ear OCT device to detect biofilms in human patients. To test the device, the researchers worked with clinicians at Carle Foundation Hospital in Urbana. They scanned patients with diagnosed chronic ear infections as well as patients with normal ears; in all patients with chronic infections, they identified biofilms, whereas none of the normal ears showed evidence of biofilms.

Professor Stephen Boppart led a team that developed a new medical imaging device that can see behind the eardrum, the first in a planned suite of devices. (Image: L. Brian Stauffer)

Next, the research team plans to investigate various ear pathologies, 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 scientists hope to make their device, currently a handheld prototype, more compact, easy to use, and low cost. Welch Allyn of Skaneateles Falls, N.Y., has collaborated on the project, which was funded by the National Institutes of Health.

The team hopes also to tweak the device so that it may be applied to other areas commonly examined by primary care physicians. Doctors could change the tip of the OCT device to look at the eyes, nose, mouth 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 3-D digital imaging and being able to look at many different tissue structures in real time, noninvasively and in depth.”

The ear-imaging device is the first in a suite of OCT-based imaging tools that Boppart’s group plans to develop.

The research appeared in the online early edition of the Proceedings of the National Academy of Sciences.

To learn more about Boppart’s work in biomedical imaging, listen to the Photonics Media webinar “The Future of Imaging, Three Perspectives.”

For more information, visit: www.illinois.edu