The new system, identified as De-scattering with Excitation Patterning (or DEEP), overcomes previous challenges with deep tissue microscopy and may revolutionize imaging methodology.
Challenging the boundaries of microscopy to understand complex biological systems
Until now, microscopy techniques have been limited by a tradeoff between image quality or speed when it comes to exploring deep tissue biological systems. To overcome such limitations, microscopists have attempted to find a way to produce faster, higher-quality, deep-tissue imaging of living subjects.
Such advantages would provide key insights for many disciplines including the spatiotemporal dynamics of cellular networks, disease infection, or cell regeneration.
In a new study reported in Sciences Advances, Dushan N. Wadduwage, a John Harvard Distinguished Science Fellow in Imaging at the FAS Center of Advanced Imaging, along with a team from MIT, detailed a new technique that would make such developments possible.
The researchers present a new process using computational imaging to obtain high-resolution images at a rate 100 to 1,000 times faster than other state-of-the-art technologies that use complex algorithms and machine learning. Such rapid acceleration means that the whole process only takes a matter of days rather than previous timescales requiring months of imaging processing.
The De-scattering with Excitation Patterning (or DEEP) is the new system and is the first breakthrough that could offer new understandings of how complicated tissue specimens, like the brain, functions because it can take images that aren't possible with other microscopes.
Because this has the potential to actually speed up [what you can take an image of along with how fast you can do it], scientists will be able to image fast processes they haven't been able to capture before, like what happens when a neuron res or how the signals move around in the brain because it's technically faster, you can image a larger volume of an area at one time, not just a small eld of view as you would with a slower imaging system.
It's like being able to look at a much larger picture, and this is very important for neuroscientists and other biologists to actually get better statistics as well as to see what's happening around the area being imaged.”
A technique improved from others with promising potential and applicability
Like many other imaging techniques used in biology, DEEP consists of a near-infrared laser light used to penetrate deep through biological tissue that scatters the light. In turn, this light excites the fluorescent molecules the researchers want to image and emit signals that the microscope captures to form an image.
To date, images were taken using two key techniques. First, point-scanning multiphoton microscopy provides imaging that penetrates deep into a specimen and captures high-quality images, but the process is extremely slow as the images are formed one single point at a time. Because of this time constraint, a centimeter-sized image takes months to capture, which severely limits information on faster dynamics such as neurons.
The second method is called temporal focusing microscopy, and is a faster technique in comparison, which uses images at a wider scale but at a low resolution and cannot penetrate further than a few millionths of a meter. Additionally, the fluorescence involved scatters widely, causing image degradation as soon as the camera detects it.
Contrastingly, the DEEP system allows for fast tissue penetration at a wide scale and produces high-resolution images by projecting a wide light into the subject, in a similar fashion as the temporal microscopy method, but the laser light is directed in a specific pattern based on a computational algorithm to reconstruct the scattered images.
This allows the system to take the reconstruction of structural features from millions of measurements to tens and hundreds. Moreover, DEEP can penetrate hundreds of microns into the tissue through scattering tissue comparable to point-scanning techniques.
Despite such notable advantages relative to previous methods, DEEP remains in early development but is emerging from its proof-of-concept phase.
We showed that we can image about 300 microns into the brains of live mice. But since this is only the first demonstration, almost all aspects of the technique have room for improvement.”
Improving upon an already improved system would represent pioneering work progressing the imaging of biological systems. Due to the widespread use of microscopy across scientific disciplines, this may lead to rapid innovations and understanding. Of particular value would be its applications to neuroscience and cellular biology, providing unprecedented information at a fast rate and a high resolution.