A new imaging technique developed at MIT has allowed scientists to create the first 3D images of a living cell using a method similar to an X-ray CT (computed tomography) scan. The technique could be used to produce the most detailed images yet of what goes on inside a living cell without the use of fluorescent markers or other externally added contrast agents.
The MIT team created 3D images of cervical cancer cells, showing internal cell structures, as well as images of other cell types. The technique is based on the same concept used to create 3D CT images of the human body. CT images are generated by combining a series of two-dimensional X-ray images taken as the X-ray source rotates around the object.
The researchers used a technique known as interferometry, in which a light wave passing through a cell is compared with a reference wave that doesn't pass through it. A 2D image containing information about refractive index is thus obtained. To create a 3D image, the team combined 100 2D images taken from different angles. The resulting images are essentially 3D maps of the refractive index of the cell's organelles.
With all other 3D imaging techniques, the samples must be fixed with chemicals, frozen, stained with dyes, metallized, or otherwise processed to provide detailed structural information. The current resolution of the new technique is about 500 nanometers, but the team is working on improving the resolution.
