Fludeoxyglucose (18F) SUS Lund
Radiopharmaceutical diagnostic agent for PET/CT imaging
Fludeoxyglucose (18F) SUS Lund is a radiopharmaceutical used as a diagnostic tracer in positron emission tomography (PET) combined with computed tomography (CT). It allows physicians to visualise areas of increased glucose metabolism in the body, which is essential for detecting and monitoring cancers, assessing heart muscle viability, and evaluating certain neurological conditions. This product is manufactured at Skane University Hospital in Lund and is administered exclusively by trained nuclear medicine professionals in authorised clinical settings.
Quick Facts
Key Takeaways
- Fludeoxyglucose (18F) is the most widely used PET tracer in the world, essential for cancer detection, staging, and treatment monitoring.
- It works by mimicking glucose — cancer cells and inflamed tissues absorb more of it, making them visible on PET scans.
- The radioactive fluorine-18 has a short half-life of approximately 110 minutes, meaning radiation exposure is low and temporary.
- Patients must fast for 4–6 hours before the scan and maintain adequate hydration to ensure accurate results and reduce bladder dose.
- Side effects are extremely rare; the main consideration is radiation exposure, which is kept within established safety limits.
What Is Fludeoxyglucose (18F) and What Is It Used For?
Fludeoxyglucose (18F) is the most commonly used radiopharmaceutical in positron emission tomography (PET) imaging worldwide. It consists of a molecule closely resembling glucose (the body's primary energy source) that has been labelled with the radioactive isotope fluorine-18. When injected into a patient's bloodstream, FDG is taken up by cells in the same way as normal glucose — through glucose transporter proteins (primarily GLUT-1 and GLUT-3) on cell membranes.
Once inside cells, FDG is phosphorylated by the enzyme hexokinase to form FDG-6-phosphate. Unlike normal glucose-6-phosphate, FDG-6-phosphate cannot be further metabolised through the glycolytic pathway. This means it becomes trapped inside cells, accumulating in tissues with high metabolic activity. The fluorine-18 atom in FDG undergoes positron emission decay, and the resulting gamma rays are detected by the PET scanner to create detailed three-dimensional images of glucose metabolism throughout the body.
The clinical applications of FDG-PET/CT span three major medical disciplines. In oncology, which accounts for approximately 90% of all FDG-PET scans, the tracer is used to detect primary tumours, identify metastatic spread, stage cancers, monitor treatment response, and detect recurrence. Cancer cells typically have significantly elevated glucose metabolism compared to normal tissue, making them appear as bright areas ("hot spots") on PET images. Common cancers evaluated with FDG-PET include lung cancer, lymphoma, melanoma, colorectal cancer, breast cancer, head and neck cancers, oesophageal cancer, and many others.
In cardiology, FDG-PET is used to assess myocardial viability — determining whether areas of the heart muscle that are not contracting properly are still alive (hibernating myocardium) or permanently scarred. This information is critical for deciding whether patients with coronary artery disease would benefit from revascularisation procedures such as coronary artery bypass grafting or percutaneous coronary intervention. FDG-PET is also increasingly used to diagnose cardiac sarcoidosis and prosthetic valve endocarditis.
In neurology, FDG-PET provides valuable information about brain glucose metabolism. It is used to help localise epileptic foci in patients with drug-resistant epilepsy who are being evaluated for surgery. FDG-PET can also assist in the differential diagnosis of dementia, distinguishing between Alzheimer's disease, frontotemporal dementia, and other neurodegenerative conditions based on characteristic patterns of reduced glucose metabolism in specific brain regions.
What Should You Know Before Receiving Fludeoxyglucose (18F)?
Fludeoxyglucose (18F) is a radioactive medicinal product that must be handled and administered exclusively by authorised personnel in specialised nuclear medicine departments. Before your PET/CT scan, the nuclear medicine team will carefully assess whether the procedure is appropriate for you and will take several precautions to ensure both diagnostic accuracy and your safety.
Contraindications
There are very few absolute contraindications to FDG-PET imaging. The primary contraindication is known hypersensitivity to the active substance fludeoxyglucose (18F) or to any of the excipients in the preparation. However, allergic reactions to FDG are extraordinarily rare, with only isolated case reports in the medical literature. Pregnancy is a relative contraindication, as the radiation dose to the fetus must be carefully weighed against the clinical benefit. FDG-PET should only be performed during pregnancy when the expected diagnostic information is essential and cannot be obtained by non-ionising methods.
Warnings and Precautions
Several important precautions apply to FDG-PET imaging. Blood glucose control is critical for scan quality. Elevated blood glucose levels compete with FDG for uptake into cells, reducing the sensitivity of the scan. Most centres require fasting blood glucose below 11 mmol/L (200 mg/dL), with optimal results at levels below 7 mmol/L (126 mg/dL). Diabetic patients may require special scheduling — typically early morning scans with adjusted insulin regimens.
Radiation protection principles apply to all patients receiving FDG. The radiation dose should be kept as low as reasonably achievable (ALARA principle) while still obtaining diagnostically adequate images. Patients should be well hydrated before and after the injection and should void frequently to reduce radiation dose to the urinary bladder, which receives the highest organ dose. Contact with young children and pregnant women should be limited for several hours after the procedure.
Patients should avoid strenuous physical exercise for at least 24 hours before the scan. Muscular activity increases glucose uptake into skeletal muscles, which can interfere with image interpretation and reduce the sensitivity for detecting pathological uptake. Patients should rest quietly during the uptake period (typically 60 minutes between injection and scanning) in a warm, quiet environment.
Recent treatments can affect scan interpretation. Chemotherapy can cause both false-negative results (due to reduced tumour metabolism) and false-positive results (due to inflammatory reactions). It is generally recommended to wait at least 2 weeks after the last chemotherapy cycle and 6–8 weeks after the last radiation therapy session before performing FDG-PET. Granulocyte colony-stimulating factor (G-CSF) treatment can cause diffusely increased bone marrow uptake for several weeks after administration.
Pregnancy and Breastfeeding
When a nuclear medicine procedure is being considered for a woman of childbearing potential, it is important to establish whether she might be pregnant. FDG-PET imaging during pregnancy delivers a radiation dose to the fetus that, while relatively small, is not negligible. According to the International Commission on Radiological Protection (ICRP), the estimated fetal dose from a standard FDG-PET scan is approximately 1–4 mSv, depending on the stage of pregnancy and the administered activity.
For breastfeeding mothers, FDG is excreted in breast milk in small quantities. The European Association of Nuclear Medicine (EANM) recommends interrupting breastfeeding for at least 12 hours after FDG administration. Breast milk expressed during this period should be discarded. Close physical contact with infants should also be limited for several hours to reduce their radiation exposure from external irradiation.
How Does Fludeoxyglucose (18F) Interact with Other Drugs?
Unlike conventional therapeutic drugs, fludeoxyglucose (18F) does not interact with other medications in the traditional pharmacological sense — it is not metabolised by cytochrome P450 enzymes and does not bind to drug transporters. However, numerous medications can alter the biodistribution of FDG in the body, potentially affecting diagnostic accuracy. Understanding these interactions is essential for proper scan scheduling and interpretation.
Major Interactions
The most clinically significant interactions involve medications that directly affect glucose metabolism. Insulin is the most important consideration. Exogenous insulin administration causes widespread FDG uptake into skeletal muscle and adipose tissue, dramatically reducing the signal-to-noise ratio for tumour detection. Insulin should not be administered within 4–6 hours of FDG injection. For diabetic patients requiring insulin, careful scheduling protocols have been developed by major nuclear medicine societies.
Chemotherapy agents represent another major interaction category. Active cytotoxic treatment can reduce tumour FDG uptake by killing metabolically active cancer cells, potentially leading to false-negative results. Conversely, chemotherapy-induced inflammation can cause false-positive findings. The EANM and Society of Nuclear Medicine and Molecular Imaging (SNMMI) recommend waiting at least 10–14 days after chemotherapy before performing response assessment scans, with some protocols suggesting longer intervals depending on the specific regimen.
Minor Interactions
Corticosteroids (such as prednisolone, dexamethasone) can elevate blood glucose levels, potentially reducing FDG uptake in target tissues. Additionally, high-dose corticosteroids may reduce FDG uptake in lymphoma and other lymphoid malignancies through their direct anti-tumour effects, independent of blood glucose changes. Granulocyte colony-stimulating factor (G-CSF) stimulates bone marrow proliferation, causing diffusely increased bone marrow FDG uptake that can persist for several weeks after treatment. This can make it difficult to detect bone marrow metastases. Metformin and other oral hypoglycaemic agents can cause variably increased bowel uptake of FDG, potentially complicating the interpretation of abdominal and pelvic pathology.
| Medication | Effect on Scan | Recommendation | Severity |
|---|---|---|---|
| Insulin | Increased muscle/fat uptake; reduced tumour contrast | Withhold for 4–6 hours before injection | Major |
| Chemotherapy agents | Reduced tumour uptake; inflammatory false-positives | Wait 10–14 days minimum after last cycle | Major |
| G-CSF (filgrastim, pegfilgrastim) | Diffuse bone marrow uptake | Wait at least 2–4 weeks after last dose | Moderate |
| Corticosteroids | Elevated blood glucose; reduced lymphoma uptake | Inform physician; may need dose adjustment timing | Moderate |
| Metformin | Increased bowel FDG uptake | Some centres stop 48h before; others note in report | Minor |
| Radiotherapy | Post-radiation inflammation (false-positives) | Wait 6–8 weeks after completion | Moderate |
What Is the Correct Dosage of Fludeoxyglucose (18F)?
The dosage of fludeoxyglucose (18F) is expressed in megabecquerels (MBq), a unit measuring radioactivity. Unlike conventional medications where doses are measured in milligrams, the amount of FDG administered is extremely small in mass terms (nanograms to micrograms) — the relevant parameter is the radioactivity level. Dosing is individualised based on the patient's body weight, the clinical indication, the type of PET scanner used, and local institutional protocols.
Adults
Standard Adult Dosage
The recommended activity for an adult patient weighing 70 kg is 100–400 MBq, administered as a single intravenous injection. Most centres in Europe follow EANM guidelines, which recommend approximately 3–5 MBq/kg body weight for standard whole-body oncology scans on modern PET/CT scanners. The trend in recent years has been toward lower activities (200–250 MBq for a 70 kg adult) due to improvements in scanner sensitivity and reconstruction algorithms, in line with the ALARA principle of minimising radiation exposure.
For cardiac viability studies, higher activities of 200–400 MBq may be used to ensure adequate myocardial signal. A glucose loading protocol (oral glucose drink or glucose-insulin clamp) is typically employed before injection to promote myocardial FDG uptake. For neurological indications, activities of 150–250 MBq are typically sufficient, as the brain has inherently high and relatively uniform glucose metabolism.
Children
Paediatric Dosage
The paediatric dose of FDG is calculated according to the child's body weight, following the EANM Paediatric Dosage Card (2014 revision). The recommended base activity is approximately 3 MBq/kg body weight, with a minimum recommended activity of 26 MBq to ensure diagnostically adequate image quality. The maximum paediatric dose should not exceed the standard adult dose. Nuclear medicine physicians carefully balance the need for diagnostic image quality against radiation dose in the paediatric population, where radiation sensitivity is higher than in adults.
Elderly Patients
Elderly Dosage Considerations
No specific dose adjustment is required solely on the basis of age. Elderly patients receive the same weight-based dosing as younger adults. However, elderly patients are more likely to have comorbidities such as diabetes, renal impairment, or cardiovascular disease that may affect scan scheduling, patient preparation, and image interpretation. Adequate hydration is particularly important in elderly patients to maintain renal clearance of FDG and reduce bladder radiation dose.
Renal Impairment
Renal Impairment Considerations
No dose reduction is required for patients with renal impairment. However, patients with reduced kidney function may have slower urinary clearance of FDG and its metabolites, potentially resulting in higher radiation doses to the urinary tract. Extra attention to hydration and frequent voiding is recommended. The nuclear medicine physician may choose to adjust the imaging protocol or extend the uptake period in patients with severe renal insufficiency.
Method of Administration
Fludeoxyglucose (18F) is administered as a single intravenous injection, typically into a peripheral vein in the arm (antecubital fossa). The injection itself takes only a few seconds. After injection, the cannula is flushed with saline to ensure the full dose is delivered. Patients then rest quietly in a warm, dimly lit room for an uptake period of approximately 60 minutes (range 45–90 minutes depending on the indication) before scanning commences. During the uptake period, patients should avoid talking, reading, using electronic devices, and any physical activity to minimise non-target FDG uptake.
Missed Dose
The concept of a "missed dose" does not apply to FDG in the conventional sense. FDG is given as a single administration immediately before a scheduled PET/CT scan. If the scan is postponed or cancelled after the dose has been prepared but before injection, the dose cannot be stored for later use due to the rapid radioactive decay of fluorine-18 (half-life ~110 minutes). A new dose must be prepared for the rescheduled appointment.
Overdose
Because FDG is administered in extremely small chemical quantities (sub-microgram range), a pharmacological overdose in the traditional sense is not possible. However, inadvertent administration of excessive radioactivity could result in an increased radiation dose to the patient. In such cases, the radiation dose to the patient should be estimated, and the patient should be advised to increase fluid intake and void frequently to accelerate urinary excretion. No specific antidote exists; management is supportive and focused on reducing the absorbed radiation dose through enhanced hydration and diuresis.
What Are the Side Effects of Fludeoxyglucose (18F)?
Fludeoxyglucose (18F) has an exceptional safety profile, which is one reason it has become the most widely used PET tracer globally. The amount of FDG injected is in the nanogram to microgram range — far below the threshold for any pharmacological effect. The glucose analogue structure means that FDG does not bind to receptors, does not inhibit enzymes, and does not have any therapeutic or toxic effect on the body's biochemistry at the administered doses. Consequently, true drug-related adverse effects are vanishingly rare.
The primary safety consideration with FDG is radiation exposure. Every administration of FDG delivers a small dose of ionising radiation to the patient. For a standard adult oncology scan with 250 MBq, the effective dose is approximately 4–7 mSv. To put this in perspective, this is comparable to 1–2 years of natural background radiation, or roughly equivalent to the radiation dose from a diagnostic CT scan of the abdomen. The risk from this level of radiation exposure is considered very low and is generally far outweighed by the diagnostic benefit.
The organ receiving the highest radiation dose is the urinary bladder wall, because FDG and its metabolites are excreted via the kidneys. This is why patients are strongly encouraged to stay hydrated and void frequently before and after the scan. The brain, heart, and other metabolically active organs also receive notable doses, but these remain within accepted safety parameters as defined by the International Commission on Radiological Protection (ICRP).
Rare (<1/1,000)
May affect fewer than 1 in 1,000 patients
- Injection site pain or irritation
- Brief sensation of warmth during injection
- Transient metallic taste
Very Rare (<1/10,000)
May affect fewer than 1 in 10,000 patients
- Hypersensitivity reactions (rash, urticaria)
- Nausea
- Vasovagal reactions (light-headedness, fainting)
- Anaphylactoid reactions (isolated case reports)
Radiation Effects (Expected)
Inherent to all radiopharmaceutical procedures
- Radiation exposure to patient (effective dose ~4–7 mSv per scan)
- Highest organ dose to urinary bladder wall
- Theoretical very small increase in long-term cancer risk
- Risk mitigated by hydration and frequent voiding
How Should Fludeoxyglucose (18F) Be Stored?
The storage of fludeoxyglucose (18F) is fundamentally different from that of conventional medications and is handled exclusively by nuclear medicine professionals. Due to the short physical half-life of fluorine-18 (approximately 109.77 minutes), FDG cannot be stockpiled and must be produced fresh, typically on the day of use or the day before for early morning scans.
FDG must be stored in lead-shielded containers (typically tungsten or lead vials and transport containers) to protect healthcare workers and the environment from radiation exposure. Storage temperature should be maintained below 25°C unless otherwise specified by the manufacturer, and the product should not be frozen. Each batch of FDG undergoes rigorous quality control testing before release for clinical use, including tests for radionuclidic purity, radiochemical purity, pH, sterility, and bacterial endotoxins.
The shelf life of FDG is limited by the radioactive decay of fluorine-18. Practically, this means a batch of FDG is typically used within 8–12 hours of production. The product label states the radioactivity at a specific reference time, and the actual activity at the time of injection must be calculated using the known decay constant. After the expiry time, remaining product must be disposed of as radioactive waste according to local radiation protection regulations.
Patients will never need to handle or store FDG. The entire process — from production to injection — is managed by trained nuclear medicine technologists, radiopharmacists, and radiation safety officers working within licensed nuclear medicine facilities. All handling follows strict radiation protection protocols as mandated by national regulatory authorities and guided by international organisations such as the International Atomic Energy Agency (IAEA) and the ICRP.
What Does Fludeoxyglucose (18F) SUS Lund Contain?
Fludeoxyglucose (18F) SUS Lund is a clear, colourless to slightly yellow, sterile solution for intravenous injection. The active substance is fludeoxyglucose (18F), with a chemical name of 2-deoxy-2-[18F]fluoro-D-glucose. The molecular formula is C6H1118FO5 and the molecular weight is approximately 181.15 g/mol (with the fluorine-18 isotope).
The amount of FDG in each injection is remarkably small from a chemical perspective. At the time of injection, the mass of FDG is typically in the nanogram to low microgram range — far below any pharmacologically active threshold. It is the radioactivity (measured in megabecquerels) rather than the chemical mass that determines the dose.
The excipients (inactive ingredients) in the solution serve to maintain the correct pH, osmolality, and stability of the product. These typically include:
- Sodium chloride — to maintain isotonicity with blood
- Sodium citrate — as a pH buffer
- Citric acid — as a pH buffer
- Water for injections — as the solvent (to European Pharmacopoeia standard)
The solution is supplied in multidose glass vials with a radioactivity range of 400 MBq to 90 GBq at the time of calibration. The wide activity range reflects the fact that vials are produced with high initial activity and multiple patient doses can be drawn from a single vial throughout the day, with the activity decreasing as fluorine-18 decays. Each vial is labelled with the total activity at a specified reference date and time, the batch number, the expiry date/time, and the volume.
Frequently Asked Questions About Fludeoxyglucose (18F)
Fludeoxyglucose (18F), commonly known as FDG, is a radioactive glucose analogue used as a tracer in PET/CT scans. It is primarily used in oncology to detect, stage, and monitor cancers; in cardiology to assess myocardial viability; and in neurology to evaluate brain conditions such as epilepsy and dementia. Cancer cells have higher glucose metabolism than normal cells, making FDG-PET highly effective at identifying malignancies. Approximately 90% of all FDG-PET scans are performed for oncological indications.
FDG has an excellent safety profile and has been used millions of times worldwide over more than 30 years. The radiation dose from a standard FDG-PET scan is approximately 4–7 mSv, comparable to 1–2 years of natural background radiation. Adverse drug reactions are extremely rare (less than 0.002% of administrations). The fluorine-18 isotope has a short half-life of approximately 110 minutes, meaning radioactivity decays rapidly. The primary safety measure is adequate hydration and frequent voiding to reduce bladder dose.
Patients should fast for at least 4 to 6 hours before the scan, drinking only water. Blood glucose should ideally be below 11 mmol/L (200 mg/dL). Diabetic patients may need special scheduling or insulin adjustments — discuss this with your doctor. Avoid vigorous physical exercise for 24 hours before the scan. Inform your nuclear medicine team about all medications you are taking, especially insulin, corticosteroids, and any recent chemotherapy or G-CSF treatment. Wear comfortable, warm clothing and expect to spend 2–3 hours at the department.
The entire process typically takes 2 to 3 hours. After arriving at the department, your blood glucose will be checked and FDG will be injected intravenously. You then rest quietly for approximately 60 minutes (the "uptake period") while the tracer distributes throughout your body. The actual PET/CT scan takes approximately 20 to 40 minutes. After the scan, you can typically leave the department and resume normal activities, though you should drink extra fluids and limit close contact with young children and pregnant women for a few hours.
FDG-PET scans are generally avoided during pregnancy due to radiation exposure to the fetus. The scan should only be performed if the expected clinical benefit clearly outweighs the potential radiation risk. For breastfeeding mothers, the EANM recommends interrupting breastfeeding for at least 12 hours after FDG injection. Breast milk expressed during this period should be discarded. Close contact with infants should also be limited for several hours after the scan. Always discuss your pregnancy or breastfeeding status with your nuclear medicine team before the procedure.
Fasting is essential because elevated blood glucose competes with FDG for uptake into cells, reducing the quality and sensitivity of the scan. When blood glucose is high, less FDG is taken up by tumours and other target tissues, potentially causing abnormalities to be missed. Drinking plenty of water (before and after the injection) serves two purposes: it helps maintain stable blood glucose levels and it promotes frequent urination, which reduces the radiation dose to the urinary bladder — the organ that receives the highest radiation dose during an FDG-PET scan.
PET (Positron Emission Tomography) and CT (Computed Tomography) provide different types of information. CT uses X-rays to create detailed anatomical images showing the structure and shape of organs and tissues. PET uses radioactive tracers like FDG to show metabolic activity — how cells are functioning. Modern PET/CT scanners combine both technologies in a single examination, allowing doctors to see both the anatomy (CT) and the metabolic activity (PET) at the same time. This combined information is far more powerful for cancer diagnosis and staging than either modality alone.
References
- European Medicines Agency (EMA). Fludeoxyglucose (18F) — Summary of Product Characteristics. EMA Marketing Authorization Documents. Available at: ema.europa.eu.
- Boellaard R, Delgado-Bolton R, Oyen WJG, et al. FDG PET/CT: EANM procedure guidelines for tumour imaging: version 2.0. European Journal of Nuclear Medicine and Molecular Imaging. 2015;42(2):328–354. doi:10.1007/s00259-014-2961-x.
- Delbeke D, Coleman RE, Guiberteau MJ, et al. Procedure Guideline for Tumor Imaging with 18F-FDG PET/CT 1.0. Journal of Nuclear Medicine. 2006;47(5):885–895.
- International Commission on Radiological Protection (ICRP). Radiation Dose to Patients from Radiopharmaceuticals. ICRP Publication 128. Annals of the ICRP. 2015;44(2S).
- Lassmann M, Treves ST, EANM/SNMMI Paediatric Dosage Harmonization Working Group. Paediatric radiopharmaceutical administration: harmonization of the 2007 EANM paediatric dosage card (version 1.5.2008) and the 2010 North American consensus guidelines. European Journal of Nuclear Medicine and Molecular Imaging. 2014;41(5):1036–1041.
- World Health Organization (WHO). WHO Model List of Essential Medicines — 23rd List, 2023. Geneva: WHO; 2023. Section 14.3: Diagnostic agents — Radiopharmaceuticals.
- Silberstein EB. Prevalence of Adverse Reactions to Positron Emitting Radiopharmaceuticals in Nuclear Medicine. Journal of Nuclear Medicine. 1998;39(12):2190–2192.
- European Association of Nuclear Medicine (EANM). EANM Guidelines on Molecular Imaging of Myocardial Viability. European Journal of Nuclear Medicine and Molecular Imaging. 2020;47:1183–1207.
- Society of Nuclear Medicine and Molecular Imaging (SNMMI). Appropriate Use Criteria for 18F-FDG PET/CT in Oncology. Journal of Nuclear Medicine. 2022;63(12):1851–1873.
- European Pharmacopoeia (Ph. Eur.). Monograph: Fludeoxyglucose (18F) Injection. 11th Edition. 2023.
Medical Editorial Team
This article has been written and reviewed by the iMedic Medical Editorial Team, comprising licensed specialist physicians in nuclear medicine, clinical pharmacology, and oncology. All content follows the GRADE evidence framework and adheres to guidelines from the WHO, EMA, FDA, EANM, and SNMMI.
Written by iMedic's medical editorial team with expertise in nuclear medicine and radiopharmaceuticals. Content based on European Pharmacopoeia monographs, EMA-approved SmPCs, and peer-reviewed nuclear medicine literature.
Independently reviewed by the iMedic Medical Review Board. All clinical claims verified against EANM/SNMMI guidelines and current evidence. No conflicts of interest. No pharmaceutical industry funding.