Analysis of Tissue Specimens by Matrix-Assisted Laser Desorption/Ionization Imaging Mass Spectrometry in Biological and Clinical Research

An analysis of tissue specimens by matrix-assisted laser desorption/ionization (MALDI) imaging mass spectrometry (IMS) in biological and clinical research is studied. In a profiling mode, data are collected from regions of interest defined by tissue pathology, while in imaging mode, the entire sample surface is raster sampled to reproduce an image of the specimen-based ion-specific ion intensities. The complete data set is comprised of many hundreds or thousands of m/z values, and the intensities of each ion can be plotted in a false color display. The resulting set of ion images is used to accurately portray the spatial distribution of the molecules that comprise the sample. After spotting with matrix, the coordinates of the matrix spots are registered to the mass spectrometer and spectra are automatically acquired from each location. Careful planning, attention to detail, and cleanliness in laboratory practices are required to avoid unwanted loss of sensitivity, loss of spatial resolution, or problems with sample stability.