Professor Rusty Lansford compares fluorescent microscopy, which images at the molecular level, and MRI, which images at the cellular/neural level.

There are a variety of different imaging modalities that we carry out at the Biological Imaging Center at Caltech. The head of the institute, Scott Frazier, had this grand vision of carrying out dynamic imaging. So we’ve assembled a variety of microscopes that allow you to fluorescently follow these green fluorescent proteins using lasers. They are very sophisticated microscopes. Our microscopes probably cost more than most peoples’ homes. They can range anywhere from a half to a quarter million dollars and so they are very sophisticated microscopes. What is wonderful about them is that you can get this very tight resolution. Typically, the way you figure it out is the wavelength of light divided by two would be the resolution. The visible wavelength of light, let’s pretend is 500 nanometers and so we can resolve structures that are about 250 nanometers. A nanometer is 1 x 10(-9) meters, so incredibly small, smaller than you can see with your naked eye. So what we try to do with that is that we’ll put these under these scopes and build incubators all around them to keep a quail egg alive, warmth and proper gases and everything so they are happy, and they’ll develop normally. We’ll window the inside of the egg and see what’s going on inside that. But even with all this sophistication we can only see maybe about 2-400 microns deep. So, we have got our x and our y [axes] and it’s that z. An embryo can be millimeters deep, so we cannot image everything but what we do image, we image with a very high resolution. MRI, magnetic resonance imaging, allows a slightly different approach where you can image entirely through the developing embryos in these giant MRI machines. Our MRI machines are more MRI microscopes and they have a million times higher resolution than what you would typically get in your clinical MRI. But that still only affords us resolution in that 20 to 80 micron voxel resolution. A voxel is something that measures in x, y, and z – we are getting the extra depth there. So that’s very nice and we can image the tissues but we’re losing the true cellular resolution. So, these are two different toys for imaging, for two different areas. One is kind of more tissue, larger but all the way through the embryo, the other one we get cut off at a certain process so we have to get more creative about what we’re doing. Those are just two of many, many imaging ways in which you can get at something.

fluorescent microscopy, dynamic imaging, mri magnetic resonance imaging, mri machines, voxel, nanometers, microscopes, rusty, lansford