February 29, 2024 Issue 25

Who said that?

"The most important thing in communication is hearing what isn't said."

(⇓ Scroll to the bottom for the answer.)

To hear what isn't said, you need to hear what is said first. In this issue, join my journey down a rabbit hole about hearing that led me back to CT.

How do our brains hear sound? 

Have you ever wondered how sound signals make their way to our brains? I have, and this popular science question led me to a study of the human middle ear using time-resolved CT.

If you are not familiar with how our brains "hear" sound, this video by the National Institutes of Health (NIH) provides an overview:

👂 Journey of Sound to the Brain by NIH

How do people figure out all of this? The anatomy of the middle ear, the area behind the eardrum, has traditionally been studied by sectioning of tissue, a technique called histology. This technique has a risk of deformation and does not allow the dynamic study of the sound transmission. This is where CT comes in.

Traditional micro-CT has eliminated the risk of deformation, but it isn't fast enough to observe how sound is transmitted from the eardrum to the inner ear. Dynamic observation of the middle ear requires brighter and more coherent X-rays.

Schmeltz et al. at Paul Scherrer Institute, Swiss Light Source, used synchrotron-based phase-contrast microtomography and post-gating algorithm to resolve the fast micromotions of the middle ear structure at 128 Hz. They used ex-vivo fresh-frozen human temporal bones. The results are beautiful. The 3D renderings they produced from this study show the micron-level movement of the tiny bones (malleus, incus, and stapes) you saw in the NIH video. This time, these are not computer graphics but actual CT data.

This study was recently published in Communications Biology: Schmeltz, M., Ivanovic, A., Schlepütz, C.M. et al. The human middle ear in motion: 3D visualization and quantification using dynamic synchrotron-based X-ray imaging. Commun Biol 7, 157 (2024). https://doi.org/10.1038/s42003-023-05738-6

👓 Read the article

From the Archive: Mini Tutorial Series

Thank you for being a subscriber of the X-ray CT Email Updates newsletter. This issue marks the two-year anniversary. I thought you might have signed up only recently and missed some of the old but still useful content. Here is one: Have you watched the mini tutorial series - X-ray CT Explained with ImageJ?

This is a collection of 5-10 min videos that explain basic concepts of X-ray CT, such as reconstruction, denoising, segmentation, and quantitative analysis using FIJI, a distribution of the open-source ImageJ. You can download FIJI and sample images for each episode to go through the exercises yourself.

If you are new to CT or teaching CT, you might find these tutorials useful.

▶️ Watch Mini Tutorial - X-ray CT Explained with ImageJ

"The most important thing in communication is hearing what isn't said."

Photo by Jeff McNeill

That's a wrap. Please let us know how we can help you learn more about X-ray CT. We love to hear from you!

Aya Takase

Head of Global Marketing Communications

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