18F-Fluorodeoxyglucose (FDG) PET/CT for Tumor Localization — Intravenous Contrast
An FDG PET/CT scan uses a radioactive glucose tracer and CT imaging to help locate areas of increased metabolic activity, including possible tumors.
["This scan helps identify and map areas of abnormal metabolic activity that may represent cancer."]
Key facts at a glance
- LOINC
- 89712-4
- Short code
- PET+CT Tum loc Ltd--W 18F-FDG+contr IV
- Synonyms
- PET+CT Tum loc Ltd--W 18F-FDG+contr IV
- Category
- liver
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- pt-ct
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
What is this test?
18F-FDG PET/CT combines positron emission tomography with CT imaging. A radioactive glucose-like tracer is given intravenously, and the scan shows where tracer accumulates in the body along with detailed anatomic images from CT.
Why might I need this test?
This test may be used to locate a suspected tumor, assess the activity of known lesions, help stage or monitor cancer, or investigate unexplained findings. It can also identify areas of increased or decreased metabolic activity outside a specific organ.
How is the test performed?
After the tracer is given through a vein, you lie still on a table while the PET scanner detects radiation from the tracer. CT images are obtained at the same time or separately and combined with the PET images. The scan usually takes about 30–60 minutes, but total appointment time may be longer.
How do I prepare for the test?
Follow the imaging center's instructions about eating, drinking, and activity before the scan. You may be asked to limit sugar or carbohydrates and avoid strenuous exercise. Tell the care team if you are pregnant, breastfeeding, or have diabetes, and ask which medications or other recent tests could affect the results.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Areas of increased FDG uptake may reflect active tumor, but inflammation or infection can produce a similar pattern. Reduced uptake can occur in some tumors or tissues with low metabolic activity. Results are interpreted with CT findings, the clinical history, and other tests, so an abnormal PET/CT does not by itself establish a cancer diagnosis.
Short name
FDG PET/CT for Tumor Localization
Frequently asked questions
Does the scan use intravenous contrast?
Is an FDG PET/CT scan painful?
Will I be radioactive after the test?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
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Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy