PRL and pituitary gland adenoma: They validated the capability of MALDI-MSI to image prolactin (PRL), growth hormone (GH), adrenocorticotropic hormone (ACTH) and thyroid stimulating hormone (TSH) within normal glands and adenomas, but also submitted the MSI data to principal component analysis to evaluate the different protein signatures among nonpathological human pituitary glands, hormone secreting and non-secreting human pituitary adenomas.