Ear Imaging Technology

[Samir]

Based on my previous thread, I would like to use this thread to post about the current and future developments of middle and inner ear imaging technologies.

Why do we need inner ear imaging technology?
"As otology enters the field of gene therapy and human studies commence, the question arises whether audiograms - the current gold standard for the evaluation of hearing function - can consistently predict cellular damage within the human inner ear and thus should be used to define inclusion criteria for trials. Current assumptions rely on the analysis of small groups of human temporal bones post mortem or from psychophysical identification of cochlear "dead regions" in vivo, but a comprehensive study assessing the correlation between audiometric thresholds and cellular damage within the cochlea is lacking.
...
Audiometric thresholds do not predict specific cellular damage in the human inner ear. Our study highlights the need for better non- or minimally-invasive tools, such as cochlear endoscopy, to establish cellular-level diagnosis and thereby guide therapy and monitor response to treatment."
Source: Human audiometric thresholds do not predict specific cellular damage in the inner ear

Why do we need middle ear imaging technology?
"Otitis media (OM), a middle-ear infection, is the most common childhood illness treated by pediatricians. If inadequately treated, OM can result in long-term chronic problems persisting into adulthood. Children with chronic OM or recurrent OM often have conductive hearing loss and communication difficulties and require surgical treatment.
...
Recent clinical studies have shown evidence of a direct correspondence between chronic OM and the presence of a bacterial biofilm within the middle ear. Biofilms are typically very thin and cannot be recognized using a regular otoscope. Here we report the use of optical coherent ranging techniques to noninvasively assess the middle ear to detect and quantify biofilm microstructure.
...
Information on the presence of a biofilm, along with its structure and response to antibiotic treatment, will not only provide a better fundamental understanding of biofilm formation, growth, and eradication in the middle ear, but also may provide much-needed quantifiable data to enable early detection and quantitative longitudinal treatment monitoring of middle-ear biofilms responsible for chronic OM."
Source: Noninvasive in vivo optical detection of biofilm in the human middle ear

Inner Ear Imaging

Technologies

• Optical Coherence Tomography (OCT)
  • Volumetric Optical Coherence Tomography (VOCT)
    • Volumetric Optical Coherence Tomography Vibrometry (VOCTV)

Research Institutes
California Institute of Technology
Harvard University
Imperial College London
Indian Institute of Technology
Kyoto University
Linköping University
Oregon Health & Science University
Stanford University
Texas A&M University
University of Washington
École Polytechnique Fédérale de Lausanne

News Articles
2014: https://www.ecnmag.com/news/2014/07/high-res-images-inner-ear-could-lead-new-hearing-loss-therapies
2014: http://engineering.tamu.edu/news/2014/07/07/applegate-inner-ear

Research Papers
2017: https://www.osapublishing.org/abstract.cfm?uri=BODA-2017-BoM4A.5
2016: http://www.jneurosci.org/content/36/31/8160
2016: https://www.nature.com/articles/srep33288
2016: http://www.pnas.org/content/113/30/E4304
2015: http://www.pnas.org/content/112/10/3128.abstract
2014: http://journals.lww.com/otology-neu...o_Imaging_of_Mouse_Cochlea_by_Optical.31.aspx
2013: http://proceedings.spiedigitallibrary.org/proceeding.aspx?articleid=1691511
2012: http://biomedicaloptics.spiedigitallibrary.org/article.aspx?articleid=1392727

Middle Ear Imaging

Technologies

• Short-Wavelength Infra-Red (SWIR)
• Optical Coherence Tomography (OCT)
  • Low-coherence interferometry (LCI)

Research Institutes
Harvard University
Kyungpook National University
Massachusetts Institute of Technology
University of Illinois

News Articles
2016: http://news.mit.edu/2016/shortwave-infrared-instrument-ear-infection-0822

Research Papers
2016: http://www.pnas.org/content/113/36/9989.abstract
2012: http://www.pnas.org/content/109/24/9529.abstract
2001: http://jamanetwork.com/journals/jamaotolaryngology/fullarticle/482354

Influential Labs
Applegate Research Group at Laboratory for Optical and Molecular Imaging,
Texas A&M University
http://www.applegatelab.org/

Stankovic laboratory at Massachusetts Eye and Ear,
Harvard Medical School, Harvard University
http://stankovic.hms.harvard.edu/

 

[Ecip]

It will be like an eye doctor taking a photo of your optic nerve. Can't wait for this technology to develop.

 

[Jinxy]

I agree. No audiogram managed to detect a change in my hearing threshold, but yet I have tinnitus due to NIHL.
I think finding better methods to assess cellular damage in the cochlea could be a nice boost to researching a cure.

 

[Iliasp]

Did you perform an extended frequency audiogram? 8khz till 20khz?

 

[Samir]

@Iliasp, I assume that question was addressed to me?

I never did that, no. I have yet to find an audiologist in Sweden who "can" do it. I say "can" in quotation marks because I know they have equipment capable of that.

All audiologists I have been to so far have audiometers from either Interacoustics or Otometrics. These are two of the biggest manufacturers in the world. They are usually of very high quality and even their cheapest models are very high spec.

Swedish audiologist most often use PC based audiometers, and they even print out your results on a nice A4 paper in color. They don't jot it on a piece of paper manually like I have seen some audiologist do it in the US. That's so old school! Sometimes you can barely tell what it says, depending on the penmanship of the audiologist. Audiograms are imprecise as it is, and here you have the penmanship of the clinician to take into account. That's just so silly to me. We all use computers now, and a good color printer costs no more than $150.

If you look at the specs for these audiometers, you will see that most of them are capable of EF tests (above 8000 Hz). But the "gold standard" hearing test goes only up to 8000 Hz. It has been standardized according to ANSI, and maybe some other standards organization. So anything beyond 8000 Hz is pretty much experimental and on a "will" rather than "can" basis. So you need to find an audiologist who is willing to step out of his or her line of duty and do an EF test on you.

I am not 100% sure on this one, but I believe that the original ANSI standard was created for the purpose of assessing who can benefit from a hearing aid. I need to do more research. The original document is from 1977 it appears. A lot of research and progress has happened since that year. One obvious milestone for audiology is the first ever experimental demonstration of Oto Acoustic Emissions (OAE) in 1978 by Prof. David Kemp. One year after the ANSI document on hearing aids/tests.

The general opinion is that hearing tests were never designed to really asses the damage of your inner ear (or middle ear). They were designed to see if you could benefit from a hearing aid. But the brain plays a much bigger role in the sense of hearing than what we previously knew. We know that now! But we still use our old ways of measuring hearing and potential ear damage. These tests are not adequate to measure minimal or even mild noise induced ear damage. We can do better in the 21 century, and we will.

As long as you can hear well up to 8000 Hz, from an audiologist point of view you do not have hearing loss. And if you do, then you need hearing aids. As simple as that! But yes, people can have visible hearing loss that improves over time. I have seen this first hand on my own audiograms. It appeared as if my mild loss at 6000 Hz improved to near normal. And... that's when I started having tinnitus. Audiograms are useless for minimal to mild hearing loss. I rest my case! (I can send the audiograms in case anyone is interested.)

 

[Samir]

No audiogram managed to detect a change in my hearing threshold, but yet I have tinnitus due to NIHL.

In my case, a mild loss was detected mainly at 6000 Hz. A few months later I did another test, and it showed normal to near normal result at 6000 Hz. This is what doctors mean when they say "give it time, maybe your hearing will recover." And... that's when I started having a tinnitus increase.

So yes, audiograms cannot be trusted. As long as you don't have moderate to profound hearing loss. But in that case, you don't need a hearing test to tell you that you don't hear well.

I will have to do more research on this, but it appears that the original "standard" for hearing tests was declared in an American ANSI document in 1977. It was closely related to the electronic, analog hearing aids. It was revised in 1997 and then again in 2003. But they still can't detect "hidden hearing loss". They still focus on providing hearing aids.

 

[DoNotGoGentle]

That is BS that won't test over 8000 hz. Experimental BS!!! What load of crap! In the future they will test for hidden hearing loss and this up to 8000 hz will stop. Once We can regenerate ear hair cells another option other then hearing aids.

 

[Paulmanlike]

It will be like an eye doctor taking a photo of your optic nerve. Can't wait for this technology to develop.

This is called fundus photography, however recently they use something called OCT which is a 3D image of the retina, it sees beneath he surface of the eye where's fundus photography only sees a birds eye view.

I think it mentioned something about OCT somewhere in one of those links, which in eye detection diseases is extremely accurate and can even see diseases before they develop.

 

[Ecip]

In my case, a mild loss was detected mainly at 6000 Hz. A few months later I did another test, and it showed normal to near normal result at 6000 Hz

It makes total sense to me that your hearing would improve as the brain turns up the 'gain' and then causes tinnitus due to that extra input.
If a guy could just reduce the brains 'gain' in the lost frequency range, tinnitus would disappear.

 

[HomeoHebbian]

The only (relatively) non-invasive optical access to cochlea is through the round window membrane. If successful, this would only provide a view of the extreme high-frequency cochlear base, which encodes very high frequencies (>= 14 kHz) and is gonzo in just about any adult who hasn't spent their life in a quiet room. The rest of the cochlea is behind the densest bone in the human body.

All this tech is only usable in cadaveric specimens or invasive surgery in animals.

I haven't read the links but I follow this tech fairly closely. I don't see this work being very realistic for non-invasively visualizing inner ear damage.

 

[Paulmanlike]

The only (relatively) non-invasive optical access to cochlea is through the round window membrane. If successful, this would only provide a view of the extreme high-frequency cochlear base, which encodes very high frequencies (>= 14 kHz) and is gonzo in just about any adult who hasn't spent their life in a quiet room. The rest of the cochlea is behind the densest bone in the human body.

All this tech is only usable in cadaveric specimens or invasive surgery in animals.

I haven't read the links but I follow this tech fairly closely. I don't see this work being very realistic for non-invasively visualizing inner ear damage.

Have you heard of Optical Coherence Tachnography

Aka OCT

 

[Samir]

The only (relatively) non-invasive optical access to cochlea is through the round window membrane.

You are referring to the minimally invasive µOCT probe that Dr. Stankovic has been working on?

If successful, this would only provide a view of the extreme high-frequency cochlear base, which encodes very high frequencies (>= 14 kHz)

I don't recall reading that. What's your source on this?

 

[Samir]

Up until very recently, I didn't know there there was work being done on a new middle ear imaging otoscope. They already have a working prototype. Of course, only time will tell how useful it is in clinical use. It's also easier to make something like that for the middle ear, doing the same for the inner ear will be much more difficult.

 

[Samir]

Here we have Brian Applegate talking about the importance and challenges of inner ear imaging. This video is from 2014.

 

[Samir]

This is the middle ear OCT/LCI prototype by University of Illinois and Kyungpook National University!



This is the SWIR prototype by Massachusetts Institute of Technology!



I believe the first one is the older of the two. It's nice to see these ideas finally materialize.

 

[HomeoHebbian]

Have you heard of Optical Coherence Tachnography

Aka OCT

No, but I have heard of optical coherence tomography!

 

[HomeoHebbian]

I don't recall reading that. What's your source on this?

Yes, I'm referring to non-invasively visualizing damage in the inner ear. It seems self-evident that the only point of optical access is the round window and that the round window is proximal to the high-frequency base of the cochlea. Therefore, it seems that techniques that offer cellular resolution (which would be needed to visualize IHC vs OHC vs supporting cell vs nerve fibers) would be limited to the extreme base of the cochlea. Clinically speaking, this region is relatively uninteresting. But it's entirely possible that engineers are thinking of ways to overcome these optical boundaries and I would be very pleased to be proven wrong!

My point is that I think there are some cool optical/biomedical engineering idea that could be tested in the inner ear but it is unlikely to yield anything terribly helpful for clinical questions in the near-term (or intermediate-term... or probably long-term).

Middle ear imaging is a different matter altogether.

 

[Samir]

Yes, I'm referring to non-invasively visualizing damage in the inner ear. It seems self-evident that the only point of optical access is the round window and that the round window is proximal to the high-frequency base of the cochlea. Therefore, it seems that techniques that offer cellular resolution (which would be needed to visualize IHC vs OHC vs supporting cell vs nerve fibers) would be limited to the extreme base of the cochlea.

That's true. Ideally, it would be best to see the cells like under microscope, i.e. optically. But maybe we can find other ways to fill the gaps? So! Here comes the next acronym. Have you heard of VOCTV?

Clinically speaking, this region is relatively uninteresting.

Why is it uninteresting? Humans start loosing their hearing from 20000 Hz, do they not? That's higher than 14000 Hz. I can think of at least a few questions that might get an answer using these high-base imaging technologies, or perhaps old questions could get new or improved answers.

But it's entirely possible that engineers are thinking of ways to overcome these optical boundaries and I would be very pleased to be proven wrong!

Just because it's difficult doesn't mean we should stop in our tracks. What's possible has already been done. It's the impossible that's intriguing. Up until relatively recently, no one could conceive such concept as super-resolution microscopy.

Middle ear imaging is a different matter altogether.

Yet people get misdiagnosed for middle ear pathologies. Perhaps even get tinnitus as a result of wrong treatment. Despite being seemingly trivial, I welcome these innovations.

 

[GregCA]

Clinically speaking, this region is relatively uninteresting.

Maybe you don't find it interesting, but some people may benefit from understanding what's happening at the base of the cochlea. I've suffered damage in that area due to otosclerosis and am left with HF hearing loss post surgery, and of course its accompanying painful HF tinnitus.
I think it would help me greatly to understand that "relatively uninteresting area" better, because nobody is currently able to tell me why I've incurred that sensorineural HL and what is really going on in there (each doctor I talk to has his/her own theory about it).
Possibly it would help understand presbycusis better, and we know that happens to pretty much everyone as they age.
Lastly if there are treatments that are administered topically, it would be good to be able to "see" their effects even if it's localized to that area.

 

[Samir]

Possibly it would help understand presbycusis better, and we know that happens to pretty much everyone as they age.
Lastly if there are treatments that are administered topically, it would be good to be able to "see" their effects even if it's localized to that area.

I agree! Presbycusis, Ototoxicity, Cisplatin therapy in children... etc.