Here’s a follow up on technology that one day might be quite useful for a range of clinicians, from pathologists to surgeons. We’ve seen DESI (Desorption Electrospray Ionization) before. (Purdue, Vanderbilt Use Mass Spectrometer to Detect Cancer; DESI Does Diagnostic Tissue Analysis; Mini 10 Portable Mass Spectrometer Uses New Chemical Analysis Technology).
Now this announcement from Purdue University:
Purdue University researchers have created the first two-dimensional images of biological samples using a new mass spectrometry technique that furthers the technology’s potential applications for the detection of diseases such as cancer.
The technology, desorption electrospray ionization, or DESI, measures characteristic chemical markers that distinguish diseased from non-diseased regions of tissue samples within a few seconds and has eliminated the need for samples to be treated with chemicals and specially contained.
This tool has a wide range of applications and could be used in the future to address many medical issues…
Conventional mass spectrometry requires chemical separations, manipulations of samples and containment in a vacuum chamber for assessment. DESI researchers modified a mass spectrometer, which is commonly used in biological sciences, to speed and simplify the time-consuming and labor-intensive analytical process, Ifa said.
Mass spectrometry works by first turning molecules into ions, or electrically charged versions of themselves, so they have mass and can be detected and analyzed. The DESI procedure does this by positively charging water molecules by spraying a stream of water in the presence of an electric field. These charged molecules contain an extra proton and are called ions. When the charged water droplets hit the surface of the sample being tested, they transfer their extra proton to molecules in the sample, turning them into ions. The ionized molecules are then vacuumed into the mass spectrometer, where the masses of the ions are measured and the material analyzed.
“Through analysis of the abundance of certain ions and mass ratios, the contents of the sample can be identified,” Cooks said. “This information can be used to precisely determine the location of cancerous tissue and borders of tumors.”
In this study, researchers mapped the distribution of fatty substances called lipids in a rat brain. The team was able to create a high-resolution image with a spatial resolution of less than 500 micrometers, meaning the image distinguishes small details separated by less than 1/100th of an inch. The researchers evaluated the sample by spraying small sections of it with the charged water droplets, obtaining data for each section and then combining the data sets to create an analysis of the sample as a whole, Ifa said. Software was used to map the information and create a two-dimensional image showing the distribution and intensity of selected ions.
The team is now working on the technique to improve the image resolution and has placed an instrument in the Indiana University School of Medicine, Cooks said.