Desorption Electrospray Ionization for Brain Tumor Identification

NBIB-funded researchers have developed a new and more efficient method for screening brain tumors. The method uses a technique called Desorption Electrospray Ionization Mass Spectrometry (DESI MS) to screen for 2-hydroxyglutarate (2-HG), a metabolite which is formed from a mutation in the brain tumor inducing gene IDH. The previous method that was developed 150 years ago required pathologists to take brain tissue samples and then use freezing and staining techniques to differentiate healthy tissue from malignant tumors. However, this process takes around 20 minutes to complete, which is a problem during time dependent surgeries.

Superimposed on an MRI image of the tumor the DESI-MS system shows areas clear of tumor (D11 and D2) as well as the main tumor region with a high level of the tumor metabolite 2-HG (D3.) Source: adapted from ref.1, R. Graham Cooks, Purdue University

The new technology employs mass spectrometry to determine the presence of certain metabolites in tissue samples. The tissue samples are sprayed with a charged liquid which then forms into droplets. The droplets are then absorbed into a mass spectrometer where the mass and charge of the metabolites are measured.

The process was first tested on 35 glioma samples in which twenty-one of the samples demonstrated high levels of 2-HG. After this study, researchers then installed a fully functional DESI MS system at the Advanced Multimodality Image Guided Operating (AMIGO) suite at Harvard’s Brigham and Women’s Hospital. MRI scans were used to map the tumors before the operation, and DESI MS was used to examine tissue sections from two patients, both of which accurately showed high levels of 2-HG to confirm the malignancy of the brain tumor.

From the NIH press release:

“The DESI MS system was shown to be extremely accurate and was easily adapted for use in the clinical setting. It does not have the limitations of MRI, which cannot provide information about the type of tumor, and requires that surgery be halted for an hour or longer for scanning and interpretation of results. Moreover, each operating room that contains an MRI machine costs more than $10 million. In contrast, DESI MS platforms could be set up in any operating room at a very small fraction of the cost. The DESI MS system promises to be a powerful new tool for both research and clinical applications with the potential to transform surgical care of patients with brain tumors and other solid tumors.”

PNAS paper: Intraoperative mass spectrometry mapping…

National Institute of Biomedical Imaging and Bioengineering: Imaging system guides brain tumor removal…