Updated project metadata. Updated publication reference for PubMed record(s): 33138378. MALDI mass spectrometry imaging (MSI) enables label-free, spatially resolved analysis of a wide range of analytes in tissue sections. Quantitative analysis of MSI datasets is typically performed on single pixels or manually assigned regions of interest (ROI). However, many sparse, small objects such as Alzheimer’s disease (AD) brain deposits of amyloid peptides called plaques are neither single pixels nor ROI. Here, we propose a new approach to facilitate comparative computational evaluation of amyloid plaque-like objects by MSI: a fast PLAQUE PICKER tool that enables statistical evaluation of heterogeneous amyloid peptide composition. Comparing two AD mouse models, APP NL-G-F and APP PS1, we identified distinct heterogeneous plaque populations in the NL-G-F model, but only one class of plaques in the PS1 model. We propose quantitative metrics for the comparison of technical and biological MSI replicates.