1. Epilepsy. Focal areas with increased metabolism have been seen during actual episodes of epilepsy, with decreased oxygen utilization and blood flow during interictal episodes. (PET/CT becomes an alternative to depth electrode implants.)

2. Stroke. An extremely complex pathophysiologic picture is revealed, including anaerobic glycolysis, depressed oxygen utilization, and decreased blood flow.

3. Coronary artery disease. Excellent images of decreased myocardial blood flow and perfusion are observed.

4. Dementia. Decreased glucose consumption (hypometabolic activity) is revealed by PET/CT imaging. PET/CT is used to differentiate Alzheimer disease from other types of dementia.

5. Schizophrenia. Some studies using labeled glucose indicate reduced metabolic activity in the frontal region.

6. Brain tumors. Data have been collected concerning oxygen use and blood flow relations for these tumors. The PET/CT images can also distinguish the developmental stages of cranial tumors and give information about the operability of such tumors. Gliomas have relatively good perfusion compared with their decreased oxygen utilization. The high uptake of radiopharmaceutical in gliomas is reported to correlate with the tumor’s histologic grade.

Pretest Patient Care

1. Instruct the patient about the purpose, procedure, and special requirements of PET/CT imaging. Refer to standard nuclear medicine procedures pretest precautions.

2. Advise the patient that lying as still as possible during the imaging is necessary. However, the patient is not to fall asleep.

3. Maintain a quiet environment.

4. Refer to standard NMI pretest precautions.

5. Follow guidelines in Chapter 1 for safe, effective, informed pretest care.

Excessive anxiety can alter the test results when brain function is being tested. Tranquilizers cannot be given before the test because they alter glucose metabolism.