Tissue Imaging Techniques
Although TOF has long been the mass spectrometry technique of choice for tissue imaging, this method is only capable of performing MS or MS2 detection. Through the application of MALDI and linear ion trap mass spectrometry, the effective isolation and detection of analytes of interest from tissue is made possible.
With conventional methods of tissue analysis, the sample is homogenized before the metabolites or analytes of interest are extracted. However, this process can cause analyte localization within the tissue to be lost. With direct tissue MALDI MS analysis, the identification of a specific analyte in the sample is possible and a 2-D image of the tissue can be generated, showing the precise location of the analyte. Using mass spectrometry for tissue imaging distinguishes between and provides distribution of both parent drug and metabolites, a result not possible with the most commonly used technique of whole body quantitative autoradiography.