Method for imaging mass spectrometry and imaging mass spectrometer

An imaging mass spectrometer in which a plurality of samples of a same kind are analyzed using results acquired by performing an imaging mass spectrometric analysis on each of the plurality of samples, the imaging mass spectrometer comprising:

• a measurement section configured to acquire mass spectrometric data by performing an imaging mass spectrometric analysis on each of a plurality of micro areas which are set on a sample;
• a region-of-interest setter configured to set a region of interest on each of the plurality of samples to be analyzed, and to divide each of the regions of interest into a same number of subregions each including a plurality of micro areas so that the subregions correspond to each other on the plurality of samples respectively covering roughly identical sites on the samples;
• an individual-index-value calculator configured to calculate an individual index value for each of the subregions, using mass spectrometric data acquired by the measurement section at the micro areas included in the subregion, the individual index value reflecting a similarity or difference among the plurality of samples in terms of a degree of expression of each mass-to-charge-ratio value;
• and
• a general-index-value calculator configured to calculate a general index value for each mass-to-charge-ratio value among the regions of interest of the plurality of samples, using the individual index values calculated for the mass-to-charge-ratio values for each of the plurality of subregions included in each of the regions of interest of the plurality of samples.