You will have learned from our previous post all about the importance of tissue fixation. Now, we’re going to walk you through the next step in our journey to printing geometrically accurate models of our brain collection: magnetic resonance imaging.
Magnetic Resonance imaging (or MRI, as you normally hear it referred to) is unique in its ability to acquire very high resolution images of soft tissue structures. The best part of this technology is that it allows you to acquire data non-invasively. In other words, we can look inside an animal without having to dissect it.
The instrument relies on the fact that our bodies are made up of a lot of water (and water is made up of hydrogen protons, or positively charged atoms). When you’re in the MRI machine, the magnetic fields produced are used to align the hydrogen protons in your body. Radio frequency waves are sent through the body and absorbed by the protons and then emitted as a signal. A radio frequency coil picks up the signal and transmits it to a computer, which processes the data and generates an image.
Below you can see how we used this technology to look inside the brain of the whale shark, Rhincodon typus, who’s brain we would not have been able to examine or quality otherwise.
In our case, MRI allows us to get high resolution images of the brain, which can then be digitally segmented. This is simply a fancy way of saying that we can use a computer program to color in our object in 3-dimensions, generating a 3D mesh. This mesh can be exported as a file that can be read by our 3D printer, which can then print a geometrically exact replica of the brain we originally imaged.
For this particular project, we’re using MRI because it provides very high resolution images from which we can generate high quality 3D printed models. There are a number of handheld scanners on the market, but it’s important to remember that what comes out of the 3D printer is only as good as the data that goes into it. We’ll be exploring 3D printing and expectations vs. reality in our next post – hope to see you there!!
1.Yopak and Frank (2009) Brain Size and Brain Organization of the Whale Shark, Rhincodon typus, using Magnetic Resonance Imaging. Brain Behavior and Evolution 74: 121-142 (read here)