Delicate surgery to restore hearing improved by imaging

cochlear implant CT
 Images produced by the CLS (top right) as compared to typical micro-CT images (top left). The resulting CLS images help develop a detailed atlas for the inner ear. Images courtesy of Dr. Mai Elfarnawamy.

Surgeons rely on medical imaging to help them plan precise surgical operations. Imaging allows them to peer inside the body to see the details of what it is they are about to perform surgery on.

The same holds true for cochlear implants – the insertion of a small electronic hearing device that helps profoundly deaf patients. But the cochlea, the snail-shaped structure in the inner ear responsible for hearing, is very small and resulting images from clinical imaging devices tend to be fuzzy. Images lack details such as internal membranes and the actual length and size of the cochlea.

This is where the concept of creating a collection of maps of the cochlea comes into play, according to Dr. Mai Elfarnawany. She is a biomedical engineer at Western University using the Canadian Light Source to create such an atlas.

“The CLS’s high imaging capability has potential for revolutionizing tools for assisting surgeons performing cochlear implants,” says Elfarnawany. 

An atlas is a tool used by doctors to help them better visualize the locations of specific anatomic features that do not show up in standard clinical imaging. The atlas contains a database of images with fine details that can be overlaid on lower-resolution clinical images from patients.

Once the images are overlaid, they can be manipulated to line-up exactly, allowing surgeons to see where otherwise difficult to identify features are located. The images may even use colour-coding or labels to highlight specific anatomical sites.

Mai Elfarnawany
Dr. Mai Elfarnawany

To create an atlas, high quality images are needed of a series of samples. Researchers selected 20 cochleae that provided a good cross section of typical cochlea to scan at the CLS, which could provide the necessary level of imaging detail.

“Everyone’s cochlea is a little different in size, shape, the number of turns of that snail shape. The samples we used span the range of sizes of the cochlea,” Elfarnawany said.

Now that the scans are complete, the research team is developing software that will allow surgeons to use the image database to plan cochlear implant surgeries and to customize electrodes for individual patients.

Elfarnawany, M., S. Riyahi Alam, S. A. Rohani, N. Zhu, S. K. Agrawal, and H. M. Ladak. "Micro?CT versus synchrotron radiation phase contrast imaging of human cochlea." Journal of microscopy (2016). DOI: 10.1111/jmi.12507 

Story by Pippa Wysong

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