Imaging in the biomedical sciences has been a critical tool for scientists to understand the inner workings of the human body. Techniques such as surgeries have existed for hundreds of years to allow people to see inside the body, but in recent years, new technologies, such as the magnetic resonance imaging, or MRI, scan, have dramatically decreased the need to use invasive techniques in order to look inside the body. In addition, these scans allow vision in real time of processes that even the most trained surgeon could not observe from a physical examination (Robb).
A functional MRI (fMRI) machine, for example, is able to reveal oxygen flow in the brain, while the positron emission tomography (PET) scan is able to reveal glucose consumption in the body (Myers). Advances in these fields have allowed both researchers and clinicians to easily understand a patient’s body, and the processes that occur within it.
However, on a molecular level, researchers have a harder time isolating and understanding the systems involved.
This is because at such a detailed level, there are a significant number of different molecules that may interact with each other, making it difficult to isolate certain molecules from an image of the specimen. A relatively new field of imaging called imaging mass spectrometry, or IMS, can be used to identify individual molecules, such as lipids or proteins, without the use of chemical tags to single out a chemical (McDonnell).
These chemical tags are very efficient in binding to specific molecules, but the tags also have their disadvantages.
Some tags change the structure or pH of a chemical, and so cannot be used for live samples. Another issue is that some tags work slowly, which is not conducive to biological research, as biological reactions tend to happen very quickly (Prescher). Because IMS avoids the use of chemical tagging, the molecules that researchers wish to study can be observed in a relatively undisturbed state.
IMS uses the technique of mass spectrometry to generate an image that separates specific molecules. What this means is that at every point of a sample, the imaging machine performs mass spectrometry, and records the data as a set, storing specific data points to points on the image. This allows computer software to be able to process the data into images, so that a researcher can be able to find where a specific molecule was present on the sample (McDonnell). Different molecules have different mass spectrometry signals, allowing the computers to easily separate the data for the researchers to see (Watrous).
Currently, IMS is limited in scope to samples that are killed first, because of the ionization that is part of the mass spectrometry process (Watrous). However, it has already been used as a method in many biomedical experiments. In one such example, researchers have used this technology to determine protein expression in certain tumors, by taking images and isolating specific proteins that may be involved in the proliferation of cancers (Stoeckli). As the ionization process becomes less dangerous to living tissue, scientists will be able to use IMS on living samples, increasing the scope of the technology greatly.
IMS could, in the future, be used as a way to determine the presence of certain toxins or tumor proliferative proteins among the other molecules in the body as a way of biopsying tumors in hospitals. In addition, once IMS is able to be performed on living samples, the technology will also be able to produce time-lapse images that provide information about the movement of molecules within cells, tissues, and organs. In this manner, IMS can be used to research cell signaling in microorganismal research. By using IMS on a colony of cells, researchers should be able to isolate antibodies, protein markers, and other chemicals that are involved in the cell signaling process and review how they interact with each other over a period of time (Watrous).
Imaging mass spectrometry is an advancing technology that will allow researchers in the biological and biomedical sciences to quickly, efficiently, and easily image and determine the molecular composition of biological specimens. Through IMS, biomolecular interactions can be isolated and identified, to give researchers a clearer view of what occurs within organisms, in conjunction with other technologies such as the MRI or PET scans.