18F-Fluorodeoxyglucose (FDG) PET/CT — Skull and Thigh for Tumor Localization
An FDG PET/CT scan uses a radioactive tracer and CT imaging to help locate tumors in the skull and thigh and assess their activity.
["This scan can help identify and locate active tumor tissue, but abnormal results may also occur with inflammation or infection."]
Key facts at a glance
- LOINC
- 82809-5
- Short code
- PT+CT Skull-thigh Tum loc W FDG+contr
- Synonyms
- PT+CT Skull-thigh Tum loc W FDG+contr
- Category
- liver
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 0.8
- Ref high
- 1.2
- Critical range
- — – 5 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- pt-ct
- CPT
- 85610
- SNOMED
- 396252006
- 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?
This is a positron emission tomography combined with computed tomography (PET/CT) scan. A small amount of radioactive FDG tracer is given through a vein, and the scanner shows where the tracer accumulates in the skull and thigh. CT provides detailed images of the anatomy.
Why might I need this test?
It may be used to locate a known tumor, evaluate whether tissue is metabolically active, stage cancer, or help guide biopsy and treatment planning. It may also be used to assess tumors that are difficult to characterize with CT or MRI alone.
How is the test performed?
After the FDG tracer is injected, you usually rest quietly for about an hour before lying on the scanner table. The machine takes PET and CT images, which are combined for detailed pictures of the skull and thigh. The scan generally takes less than an hour, although the total visit may take longer.
How do I prepare for the test?
Follow the nuclear medicine department's instructions about eating, drinking, exercise, and diabetes medications. Avoid strenuous activity for several hours beforehand if instructed, and drink water to help your body eliminate the tracer. Tell the care team if you are pregnant, breastfeeding, or may be pregnant.
Reference range
INR: 0.8-1.2 (warfarin: 2.0-3.0)N/A
Inform your healthcare provider if you are taking blood thinners. No special preparation required.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Areas of increased FDG uptake may indicate active tumor tissue, but inflammation, infection, and some other conditions can look similar. Areas with little or no uptake may suggest that a suspicious finding is less likely to be an active tumor. Results should be interpreted with your symptoms, examination, and other imaging by your care team.
Short name
FDG PET/CT tumor localization
Frequently asked questions
Is this a blood test?
Will the scan make me radioactive?
Can inflammation look like cancer on this scan?
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.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy