PET scanning, as described in the introduction to this chapter, is a nuclear study performed to assist in diagnosing central nervous system, cardiac, pulmonary, and breast disorders. Although these particular organ systems are the usual ones examined for pathological processes, this procedure can be performed to examine any part of the body to obtain clinical information regarding diseases and effects of therapeutic interventions.
A radionuclide prepared for use in this study, usually 15O, 13N, 11C, or 18F, capable of emitting a positron, is administered by IV injection or via inhalation. PET scanning follows after the radionuclide becomes concentrated in the organ to be studied. The time required for radionuclide concentration varies with the organ system. As the positron combines with negative electrons, the specialized PET scanner translates the emission from the radioactivity into color-coded images for viewing and analysis. Scanning is conducted over a period of time to allow repetition or sequencing of three-dimensional images. The expense of the study limits its use, even though it is more sensitive than are traditional nuclear scanning and SPECT scanning.
Nursing Care Before the Procedure
Client teaching and physical preparation are the same as for any nuclear scan study (see section under "Brain Scanning").
- Inform the client that the study takes 30 to 60 minutes, depending on the organ to be examined.
- Instruct the client to restrict smoking and intake of alcohol or caffeine-containing beverages for 24 hours before the study.
- Client should be instructed also to restrict medications except for a long-acting insulin that should be administered before a meal 3 to 4 hours before the study.
- Advise the client that a blindfold and earplugs are used to reduce stimuli during the study if the brain is being examined.
- History should include information about the system being studied, signs and symptoms that determined the need for the study, and results of other diagnostic tests and procedures.
Brain Study. The client is placed on a reclining bed in a semiupright position. An IV line is initiated in each arm. The radionuclide is injected into one line and serial blood samples are taken from the second line. The client is requested to perform deep breathing to reduce anxiety. Earplugs and blindfold are applied to reduce external stimuli. The client is requested to remain still during the study. Scanning of the brain begins 45 minutes after the injection, and the client is requested to read, perform letter-recognition activities, or recite a familiar quotation, depending on whether speech, reasoning, or memory is to be tested.
Heart, Lung, or Breast Study. The client is placed on the examining table in a supine position. The two IV lines are initiated as for a brain study. Scanning over the chest is performed 45 minutes after the injection of the radionuclide. The scanning takes place for 1 hour as the detectors record the radiation and establish its source in the body. A computer transforms the rays into a visual display on a screen for viewing.
Nursing Care After the Procedure
Care and assessment after the procedure are the same as for any nuclear scan study (see section under "Brain Scanning").
- Advise the client to assume a standing position slowly to prevent postural hypotension.
