A method of performing imaging mass spectrometry of a sample. The method comprises performing a first mass analysis of the sample using a first mass analyzer comprising a multi-pixel ion detector to obtain first mass spectral data representative of pixels of the sample. The method further comprises identifying clusters of pixels sharing one or more characteristics of first mass spectral data. The method also comprises performing a second mass analysis of the sample using a second mass analyzer to obtain second mass spectral data at at least one location in each cluster, wherein the number of locations is significantly less than the number of pixels in each cluster, said second mass analysis being of higher resolution than said first mass analysis. Also a mass spectrometry apparatus configured for carrying out the method.