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, metabolites, peptides or proteins by their molecular masses. Emerging technologies in the field of MSI are MALDI imaging and secondary ion mass spectrometry imaging (SIMS imaging) [1][2].
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Secondary ion mass spectrometry (SIMS) is used to analyze solid surfaces and thin films 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.
Matrix-assisted laser desorption ionization can be used as a mass spectrometry imaging technique for relatively large molecules.[2] In this version of the technique the sample, typically a thin tissue section, is moved in two dimensions while the mass spectrum is recorded.[3]
Other mass spectrometry ionization methods can also be used for MS imaging: for example desorption electrospray ionization[4].
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. [5]
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