Mass spectrometry imaging
Encyclopedia
Mass spectrometry imaging (also known as imaging mass spectrometry) is a technique used in mass spectrometry
to visualize the spatial distribution of e.g. compounds, biomarker, metabolite
s, peptide
s or protein
s by their molecular masses. Emerging technologies in the field of MSI are MALDI imaging
and secondary ion mass spectrometry imaging (SIMS imaging
) .
s by sputtering
the surface with a focused primary ion beam
and collecting and analyzing ejected secondary ions. SIMS imaging is performed in a manner similar to electron microscopy; the primary ion beam is rastered across the sample while secondary mass spectra are recorded.
section, is moved in two dimensions while the mass spectrum
is recorded.
.
Some software modules are also available for viewing mass spectrometry images in imzML format: Biomap (free), DataCubeExplorer (free), EasyMSI (CEA), Mirion (JLU).
Converters and modules are described or downloadable on http://www.maldi-msi.org
Mass spectrometry
Mass spectrometry is an analytical technique that measures the mass-to-charge ratio of charged particles.It is used for determining masses of particles, for determining the elemental composition of a sample or molecule, and for elucidating the chemical structures of molecules, such as peptides and...
to visualize the spatial distribution of e.g. compounds, biomarker, metabolite
Metabolite
Metabolites are the intermediates and products of metabolism. The term metabolite is usually restricted to small molecules. A primary metabolite is directly involved in normal growth, development, and reproduction. Alcohol is an example of a primary metabolite produced in large-scale by industrial...
s, peptide
Peptide
Peptides are short polymers of amino acid monomers linked by peptide bonds. They are distinguished from proteins on the basis of size, typically containing less than 50 monomer units. The shortest peptides are dipeptides, consisting of two amino acids joined by a single peptide bond...
s or protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
s by their molecular masses. Emerging technologies in the field of MSI are MALDI imaging
MALDI imaging
MALDI imaging is the use of matrix-assisted laser desorption ionization as a mass spectrometry imaging technique in which the sample, often a thin tissue section, is moved in two dimensions while the mass spectrum is recorded.-Applications:...
and secondary ion mass spectrometry imaging (SIMS imaging
Secondary ion mass spectrometry
Secondary ion mass spectrometry is a technique used in materials science and surface science to analyze the composition of solid surfaces and thin films by sputtering the surface of the specimen with a focused primary ion beam and collecting and analyzing ejected secondary ions...
) .
SIMS Imaging
Secondary ion mass spectrometry (SIMS) is used to analyze solid surfaces and thin filmThin film
A thin film is a layer of material ranging from fractions of a nanometer to several micrometers in thickness. Electronic semiconductor devices and optical coatings are the main applications benefiting from thin film construction....
s by sputtering
Sputtering
Sputtering is a process whereby atoms are ejected from a solid target material due to bombardment of the target by energetic particles. It is commonly used for thin-film deposition, etching and analytical techniques .-Physics of sputtering:...
the surface with a focused primary ion beam
Ion beam
An ion beam is a type of charged particle beam consisting of ions. Ion beams have many uses in electronics manufacturing and other industries. A variety of ion beam sources exist, some derived from the mercury vapor thrusters developed by NASA in the 1960s.-Ion beam etching or sputtering:One type...
and collecting and analyzing ejected secondary ions. SIMS imaging is performed in a manner similar to electron microscopy; the primary ion beam is rastered across the sample while secondary mass spectra are recorded.
MALDI imaging
Matrix-assisted laser desorption ionization can be used as a mass spectrometry imaging technique for relatively large molecules. In this version of the technique the sample, typically a thin tissueTissue (biology)
Tissue is a cellular organizational level intermediate between cells and a complete organism. A tissue is an ensemble of cells, not necessarily identical, but from the same origin, that together carry out a specific function. These are called tissues because of their identical functioning...
section, is moved in two dimensions while the mass spectrum
Mass spectrum
A mass spectrum is an intensity vs. m/z plot representing a chemical analysis. Hence, the mass spectrum of a sample is a pattern representing the distribution of ions by mass in a sample. It is a histogram usually acquired using an instrument called a mass spectrometer...
is recorded.
DESI imaging
Other mass spectrometry ionization methods can also be used for MS imaging: for example desorption electrospray ionizationDesorption electrospray ionization
Desorption electrospray ionization is an ambient ionization technique that can be used in mass spectrometry for chemical analysis. It is an atmospheric pressure ion source that ionizes gases, liquids and solids in open air under ambient conditions. It was developed in 2004 by Professor Graham...
.
Standard format for mass spectrometry images
As an extension of the mzML standard format developed by HUPO for mass spectrometry datasets, the Computis project developed the imzML standard format for mass spectrometry images.Software
Converters from Thermo Fisher format, Analyze format, GRD format and Bruker format to imzML format were developed by the Computis project.Some software modules are also available for viewing mass spectrometry images in imzML format: Biomap (free), DataCubeExplorer (free), EasyMSI (CEA), Mirion (JLU).
Converters and modules are described or downloadable on http://www.maldi-msi.org