Spectroscopy

Magnetic Resonance (MR) spectroscopy is a noninvasive diagnostic test for measuring biochemical changes in the brain, especially the presence of tumors. While magnetic resonance imaging (MRI) identifies the anatomical location of a tumor, MR spectroscopy compares the chemical composition of normal brain tissue with abnormal tumor tissue. This test can also be used to detect tissue changes in stroke and epilepsy.

How does MR spectroscopy work?

MR spectroscopy is conducted on the same machine as conventional MRI. The MRI scan uses a powerful magnet, radio waves, and a computer to create detailed images. Spectroscopy is a series of tests that are added to the MRI scan of your brain or spine to measure the chemical metabolism of a suspected tumor.

MR spectroscopy analyzes molecules such as hydrogen ions or protons. Proton spectroscopy is more commonly used. There are several different metabolites, or products of metabolism, that can be measured to differentiate between tumor types:

Amino acids

Lipid

Lactate

Alanine

N-acetyl aspartate

Choline

Creatine Myoinositol

What happens during the test?

You will lie on a moveable bed with your head cradled on a headrest and your arms at your sides. An antenna device called a “coil” will be placed over or around the area of the body to be imaged. It is specialized to produce the clearest picture of the area it is placed over. When you are comfortably positioned, the table will slowly move into the magnetic field. As the exam proceeds, you will hear a muffled “thumping” sound for several minutes at a time. This is the sound of the pictures being taken. You may be given an injection of contrast dye (gadolinium) into your arm or through an IV to enhance the images.

Because MR spectroscopy requires special tests on your tumor or lesion, it may take slightly longer than a conventional MRI. It is important that you relax and lie as still as possible. Any movement during this time will blur the picture.