Ear infections are so common that three out of four children have at least one by the time they reach age three, says the National Institute on Deafness and Other Communication Disorders, part of the National Institutes of Health. Chronic ear infections can damage children’s hearing and often require surgery to place drainage tubes in the eardrum.
Studies have found that patients who suffer from chronic ear infections may have a film of bacteria or other microorganisms that builds up behind their eardrums, similar to the way that dental plaque accumulates on teeth. Finding and monitoring these “biofilms” are important in order to properly identify and treat chronic ear infections.
But, seeing beyond the eardrum has been extremely difficult. Using a standard otoscope, a doctor is only able to observe the eardrum’s surface, not any biofilm behind it. Since the bacteria in the biofilm can cause infections, being able to visualize evidence of it is key to preventing these infections.
Now, a new medical imaging device invented by researchers at the University of Illinois at Urbana-Champaign allows doctors to view what’s behind the eardrum to better diagnose and treat chronic ear infections. They say that the device could usher in a new suite of non-invasive, 3D diagnostic imaging tools for primary care physicians and pediatricians.
Stephen Boppart, the Bliss Professor of Engineering in the Departments of Electrical and Computer Engineering, Bioengineering, and Medicine, who led the team, said, “We know that antibiotics don’t always work well if you have a biofilm, because the bacteria protect themselves and become resistant. 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.”
How It Works
The new device uses a technique called optical coherence tomography (OCT), a non-invasive imaging system used by Boppart’s group. It 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 graduate student Cac Nguyen, the lead author of the paper, published in the Proceedings of the National Academy of Sciences. “We measure the reflection, and with the reference light we can get the structure in depth.”
A single scan is performed in a fraction of a second and images a few millimeters deep behind the eardrum. The depth of the image permits doctors to not only note the presence of a biofilm, but also how thick it is and its position against the eardrum.
The study 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 Foundation Hospital in Urbana, IL, 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.
Where It Stands
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.
Boppart’s group and its collaborators, including Welch Allyn, Skaneateles Falls, NY, 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.
Since “the ‘Primary Care Imaging’ system is one that is designed to image all the tissue sites examined in the primary care office, including the ears, eyes, oral mucosa, and skin, we are exploring all of these areas in parallel,” says Boppart. “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.”
The most significant clinical impact of OCT has been in ophthalmology, where it has become the standard clinical imaging modality to screen for several retinal diseases and glaucoma. Cardiology is another field where OCT may have significant impact. Intravascular OCT has been successfully used in characterizing arterial plaques and visualizing interventional treatments like stent implantations. Oncology is one more field where OCT may find applications in tumor boundary detection, image-guided surgery, and early detection of small lesions.
For more information about this technology, visit http://biophotonics.illinois.edu .