Even the smallest of pituitary gland tumors can disrupt hormonal balance, but difficulty localizing and visualizing the margins of these millimeter-scale microadenomas complicates surgical removal of the tumors. 
Researchers demonstrate that MS imaging (MSI) can detect excess production of several key hormones in pituitary tissue samples in approximately 30 minutes, potentially allowing surgeons to precisely excise tumors while preserving a healthy gland. 
In proof-of-concept experiments, the authors used MALDI MSI, a visualization technique that helps identify large molecules in tissue samples without labeling. The authors imaged sections from six healthy human pituitary glands to determine baseline distribution of hormones, including growth hormone and adrenocorticotropic hormone. 
Next, the authors characterized the distribution of the hormones in sections from 45 pituitary adenomas, comparing the results with traditional histopathological identification methods. Because both normal and diseased tissues can produce hormones, the authors used an analytical method called principal component analysis and detected protein signatures unique to either type of tissue with high specificity. 
According to the authors, the results suggest that MALDI MSI might enable rapid molecular imaging of pituitary tumors during surgery.
http://www.pnas.org/content/early/2015/07/24/1423101112