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Brain
Brain cancer occurs when certain cells within the brain grow in an uncontrolled, abnormal, manner.
There are two main types of brain cancer. In primary brain cancer, abnormal cell growth starts in the brain. In metastatic brain cancer, cancerous cells that originate elsewhere in the body move to the brain. Brain tumors can be benign, with no cancer cells, or malignant.
The American Cancer Society estimates that more than 22,000 new cases of brain and central nervous system cancers will be diagnosed in 2011 and nearly 13,110 Americans will die from the disease.
Molecular imaging is very useful for guiding the management of brain tumors. Positron emission tomography (PET) and single-photon emission-computed tomography (SPECT) are used to determine the extent of disease, degree of malignancy and to detect cancer recurrences.
What is PET?
PET involves the use of an imaging device (PET scanner) and a tiny amount of radiotracer that is injected into the patient’s bloodstream. A frequently used PET radiotracer is (FDG), which the body treats like the simple sugar glucose. It usually takes between 30 and 60 minutes for the FDG distribution to become fixed. A CT is also obtained on the same machine so the FDG scan can be compared and fused together.
Because brain cells affected by dementia are less active, they consume, or metabolize less glucose than normal cells and will appear less bright on PET scans. Researchers are exploring the use of additional brain imaging radiotracers that may signal the presence of a brain tumor.
What is SPECT?
A SPECT scan uses a gamma camera that rotates around the patient to detect a radiotracer in the body. Working with a computer, SPECTcreates three-dimensional images of the area being studied. SPECT may also be combined with CT for greater accuracy.
Like PET, SPECT also can be used to differentiate different disease processes that produce dementia and it is increasingly used for this purpose. SPECT also plays an important role in epilepsy imaging and the surgical treatment of severe epilepsy.
What are the advantages of molecular imaging for people with brain disorders?
- molecular imaging allows metabolic activity to be directly visualized, not inferred. PET studies allow abnormal brain function to be detected before structural changes resulting from brain cell death can be seen on CT or MRI.
- PET and SPECT are highly accurate methods for evaluating surgery as a treatment option.
- molecular imaging is very useful for guiding the management of brain tumors.
- Physicians use PET and SPECT studies to determine the extent of the disease, define the degree of malignancy and to detect cancer recurrences.