Fludeoxyglucose (18F) Alliance Medical: Uses, Dosage & Side Effects

What Is Fludeoxyglucose (18F) Alliance Medical and What Is It Used For?

Fludeoxyglucose (18F) Alliance Medical contains the active substance fludeoxyglucose (18F), commonly abbreviated as ¹⁸F-FDG or simply FDG. This is a glucose analogue — a molecule that closely resembles natural glucose — in which one hydroxyl group has been replaced by the positron-emitting radioactive isotope fluorine-18. The product is manufactured by Alliance Medical and supplied as a sterile, clear, colourless to slightly yellow solution for intravenous injection. It is available in multi-dose vials with radioactive concentrations ranging from 300 MBq/mL to 3100 MBq/mL at the reference date and time of calibration.

The fundamental principle behind FDG PET imaging is the Warburg effect, first described by Nobel laureate Otto Warburg in the 1920s. Warburg observed that cancer cells preferentially use glycolysis (anaerobic glucose metabolism) even in the presence of oxygen, a phenomenon known as aerobic glycolysis. As a result, malignant tumours typically consume glucose at rates 10 to 50 times higher than normal tissue. When fludeoxyglucose (18F) is injected intravenously, it enters cells through the same glucose transporter proteins (primarily GLUT-1 and GLUT-3) as natural glucose. Inside the cell, hexokinase phosphorylates FDG to FDG-6-phosphate. However, unlike glucose-6-phosphate, FDG-6-phosphate cannot proceed further through the glycolytic pathway because it lacks the 2-hydroxyl group needed for the next enzymatic step. Consequently, FDG-6-phosphate becomes metabolically trapped within the cell, and its concentration reflects the cell’s glucose metabolic rate.

As fluorine-18 undergoes radioactive decay, it emits a positron (a positively charged electron). This positron travels a very short distance (typically less than 1 millimetre) before encountering an electron. The resulting annihilation event produces two 511 keV gamma photons that travel in nearly opposite directions (approximately 180 degrees apart). The PET scanner’s ring of detectors simultaneously registers these paired photons (a process called coincidence detection), allowing the precise location of the annihilation event to be calculated. By accumulating millions of such coincidence events, the PET scanner reconstructs a three-dimensional image showing the distribution and intensity of FDG uptake throughout the body.

Modern PET imaging is almost always performed as a combined PET/CT examination, where the PET metabolic data is fused with computed tomography (CT) anatomical images. This hybrid PET/CT approach provides both the functional information from FDG uptake and the precise anatomical localization from CT, dramatically improving diagnostic accuracy compared with either modality alone. More recently, PET/MRI scanners have also become available, combining the metabolic sensitivity of PET with the superior soft-tissue contrast of magnetic resonance imaging (MRI).

Oncology Applications

Oncology is by far the most common clinical application of FDG PET, accounting for approximately 85–90% of all FDG PET examinations worldwide. The technique is used across the entire cancer care continuum, from initial diagnosis and staging through treatment response assessment and surveillance for recurrence. FDG PET/CT is now considered the standard of care for staging and response assessment in numerous malignancies, including lung cancer, lymphoma (both Hodgkin and non-Hodgkin), head and neck cancers, colorectal cancer, oesophageal cancer, melanoma, cervical cancer, and many others.

For initial staging, FDG PET/CT can detect primary tumours, regional lymph node involvement, and distant metastases in a single whole-body examination, often revealing disease that would be missed by conventional imaging methods such as CT or ultrasound alone. In treatment response assessment, changes in FDG uptake often precede anatomical changes by weeks or months, allowing earlier determination of whether a patient is responding to chemotherapy or immunotherapy. The Deauville 5-point scale, widely used in lymphoma, and PERCIST (PET Response Criteria in Solid Tumours) are standardized frameworks for interpreting treatment response on FDG PET.

It is important to note that FDG PET is not specific for cancer. Any condition associated with increased glucose metabolism — including infection, inflammation, granulomatous disease, and certain benign tumours — can produce increased FDG uptake (false-positive findings). Conversely, some cancers with low metabolic rates (such as well-differentiated hepatocellular carcinoma, renal cell carcinoma, prostate adenocarcinoma, and mucinous tumours) may show little or no FDG uptake (false-negative findings). Clinical interpretation must always consider the complete clinical context.

Cardiology Applications

In cardiology, FDG PET is used primarily to assess myocardial viability in patients with coronary artery disease and left ventricular dysfunction. When a segment of heart muscle has reduced blood flow (ischaemia) but is still alive (viable), it shifts its energy metabolism from fatty acid oxidation to glucose utilisation. FDG PET can detect this metabolic shift, identifying so-called “hibernating myocardium” — heart muscle that is alive but functionally impaired due to chronic ischaemia. This information is critical for clinical decision-making because hibernating myocardium has the potential to recover contractile function after revascularisation (coronary bypass surgery or percutaneous coronary intervention), whereas scarred myocardium does not.

A typical viability protocol involves a rest myocardial perfusion scan (often using rubidium-82 or nitrogen-13 ammonia PET) combined with an FDG metabolic scan. A pattern of reduced perfusion but preserved FDG uptake (a “mismatch” pattern) indicates viable, hibernating myocardium. A matched reduction in both perfusion and FDG uptake suggests scar tissue. Studies have demonstrated that patients with significant amounts of viable myocardium benefit substantially from revascularisation, with improvements in heart function, symptoms, and survival.

FDG PET is also increasingly used to detect cardiac sarcoidosis and prosthetic valve endocarditis, where it can identify focal areas of inflammation within the heart that may be difficult to detect with other imaging modalities.

Neurology Applications

The brain is one of the most metabolically active organs in the body, consuming approximately 20% of the body’s total glucose supply despite accounting for only about 2% of body weight. FDG PET takes advantage of this high basal glucose metabolism to identify regions of abnormal brain activity. In neurology, FDG PET is used for several important clinical indications.

For epilepsy evaluation, FDG PET performed during the interictal period (between seizures) can identify the seizure focus as a region of reduced glucose metabolism (hypometabolism). This information is particularly valuable in patients with medically refractory epilepsy who are being evaluated for surgical resection of the epileptogenic focus. FDG PET has been shown to have higher sensitivity than MRI for detecting the seizure focus in temporal lobe epilepsy, correctly localizing the focus in approximately 70–90% of cases.

In the evaluation of dementia, FDG PET reveals characteristic patterns of regional hypometabolism that help differentiate between different types of neurodegenerative disease. Alzheimer’s disease typically shows reduced FDG uptake in the temporal and parietal cortices with relative sparing of the primary sensorimotor cortex. Frontotemporal dementia shows predominant frontal and anterior temporal hypometabolism. Dementia with Lewy bodies shows occipital hypometabolism in addition to posterior cortical changes. These distinctive metabolic patterns can aid in diagnosis when clinical presentation is ambiguous.

What Should You Know Before Receiving Fludeoxyglucose (18F)?

Fludeoxyglucose (18F) Alliance Medical is a radiopharmaceutical product that involves exposure to ionizing radiation. Every use must be justified by a qualified nuclear medicine physician who determines that the expected clinical benefit to the patient outweighs the radiation risk. This is in accordance with the internationally recognized ALARA (As Low As Reasonably Achievable) principle and the regulatory requirements of the European Medicines Agency (EMA), the International Atomic Energy Agency (IAEA), and national radiation protection authorities. The product must only be handled and administered in authorized clinical settings by personnel trained in the safe handling of radioactive materials.

Contraindications

The only absolute contraindication to fludeoxyglucose (18F) is known hypersensitivity to the active substance or to any of the excipients. Allergic reactions to FDG are extremely rare and have been reported only in isolated case reports in the medical literature. There are no other absolute contraindications; however, several relative contraindications and precautions must be carefully considered.

Poorly controlled hyperglycaemia is the most important relative contraindication. Elevated blood glucose levels compete with FDG for cellular uptake via glucose transporters, significantly reducing FDG accumulation in target tissues and degrading image quality. Most nuclear medicine departments require a blood glucose level below 11 mmol/L (200 mg/dL) at the time of injection, and many prefer levels below 8.3 mmol/L (150 mg/dL) for optimal image quality. Patients with poorly controlled diabetes may need to have their scan rescheduled after glucose optimization. Insulin administration immediately before or shortly before FDG injection should generally be avoided, as insulin drives FDG into skeletal muscle and can create diffuse muscle uptake that obscures pathological findings.

Warnings and Precautions

Several important precautions must be observed to ensure both patient safety and diagnostic image quality. Patients should fast for at least 4–6 hours before the examination. Only water (without sugar) is permitted during the fasting period. This fasting requirement ensures low circulating insulin levels and optimal tumour-to-background FDG uptake ratios. Patients should avoid strenuous physical exercise for at least 24 hours before the examination, as vigorous activity increases muscle glucose uptake and can interfere with image interpretation.

During the uptake phase (the approximately 60-minute period between FDG injection and scanning), patients should rest quietly in a warm, comfortable environment. They should avoid talking, chewing, and unnecessary movement, as any muscular activity during this period will increase FDG uptake in the active muscles, potentially masking or mimicking pathological findings. A warm environment also helps minimize brown adipose tissue (BAT) activation, which can produce prominent FDG uptake in the neck and supraclavicular regions that may be confused with lymph node metastases.

Adequate hydration before and after the examination is recommended to promote renal clearance of the radiotracer and reduce radiation exposure to the urinary bladder wall. Patients are encouraged to void frequently after the scan. In patients who are catheterized, the catheter bag should be emptied regularly.

Pregnancy and Breastfeeding

Fludeoxyglucose (18F) should not be administered during pregnancy unless the clinical need is considered essential and the expected diagnostic benefit outweighs the radiation risk to the mother and the developing fetus. The estimated fetal dose from a standard FDG PET examination is approximately 2–5 mGy, which is below the widely cited threshold of 50–100 mGy for deterministic effects. Nevertheless, the stochastic risk (increased lifetime cancer probability) of any fetal radiation exposure, however small, must be considered. Alternative imaging methods that do not involve ionizing radiation (such as MRI or ultrasound) should be explored first whenever possible.

Women of childbearing potential should be asked about the possibility of pregnancy before the examination, and pregnancy should be confirmed or excluded when clinically appropriate. If the examination is deemed essential during pregnancy, the administered activity should be minimized while maintaining diagnostic image quality.

Women who are breastfeeding should be advised to temporarily discontinue breastfeeding after the injection. The European Association of Nuclear Medicine (EANM) recommends a breastfeeding interruption of approximately 12 hours after administration. During this period, expressed breast milk should be discarded. Close contact with infants should also be limited for several hours after the injection to reduce external radiation exposure to the child.

Special Populations

In paediatric patients, FDG PET can be performed when clinically indicated, but the administered activity must be adjusted according to body weight using the EANM Dosage Card or equivalent paediatric dosing guidelines. Children are more radiosensitive than adults, and the ALARA principle is particularly important. Sedation or general anaesthesia may be required for young children or uncooperative patients to ensure adequate rest during the uptake phase and to minimize motion artefacts during scanning.

In elderly patients, no specific dose adjustment is required. However, attention should be paid to potential comorbidities such as diabetes, renal impairment, and dehydration that may affect image quality or patient safety. Adequate hydration and blood glucose management are particularly important in this population.

In patients with renal impairment, no dose adjustment is necessary as fludeoxyglucose (18F) undergoes rapid radioactive decay. The physical half-life of fluorine-18 (approximately 110 minutes) means that any retained activity decays to negligible levels within one day regardless of renal function. However, adequate hydration should be encouraged to promote urinary excretion where possible.

How Does Fludeoxyglucose (18F) Interact with Other Drugs?

Unlike conventional drugs, fludeoxyglucose (18F) is a diagnostic tracer administered at sub-pharmacological doses. It has no known pharmacological effects and does not produce drug-drug interactions in the traditional sense. However, a number of medications and clinical interventions can significantly affect glucose metabolism, tissue perfusion, and inflammatory responses, all of which can alter FDG biodistribution and potentially lead to false-positive or false-negative PET results. Understanding these “metabolic interactions” is essential for accurate image interpretation and appropriate patient preparation.

Major Interactions

Insulin is the single most impactful factor affecting FDG biodistribution. Exogenous insulin administration within 4 hours before FDG injection dramatically increases skeletal muscle and adipose tissue glucose uptake while simultaneously reducing FDG uptake in tumour tissue. This can render an entire examination non-diagnostic, with diffuse intense muscle uptake obscuring potential pathology. For this reason, all nuclear medicine guidelines strongly advise against insulin administration within 4 hours of FDG injection. Diabetic patients who require insulin should have their scans scheduled in the early morning, before their usual insulin dose, or their insulin regimen should be adjusted in consultation with their endocrinologist or treating physician.

Granulocyte colony-stimulating factor (G-CSF) and related haematopoietic growth factors cause a dramatic and widespread increase in bone marrow FDG uptake that can persist for 2–4 weeks after the last dose. This effect is caused by the massive expansion and metabolic activation of bone marrow progenitor cells stimulated by G-CSF. In patients undergoing staging or response assessment for lymphoma, myeloma, or leukaemia, this bone marrow hyperactivity can be indistinguishable from marrow infiltration by malignant cells, leading to false-positive interpretations. Current EANM and SNMMI guidelines recommend waiting at least 2 weeks (and preferably 4 weeks) after the last dose of G-CSF before performing FDG PET.

Minor Interactions

Corticosteroids affect FDG PET images through multiple mechanisms. They raise blood glucose levels (which reduces overall FDG uptake), suppress inflammatory and immune cell activity (which reduces FDG uptake at sites of infection or inflammation), and may directly reduce tumour FDG uptake in steroid-sensitive malignancies such as lymphoma. The clinical significance depends on the steroid dose, duration of use, and the clinical question being addressed. For lymphoma response assessment (particularly when using the Deauville criteria), it is important that the timing and dose of corticosteroid therapy are consistent between baseline and follow-up scans.

Metformin, the most widely prescribed oral hypoglycaemic agent for type 2 diabetes, causes increased FDG uptake in the bowel wall, presumably due to its effect on intestinal glucose transporters and metabolism. This physiological bowel uptake can be intense and diffuse, potentially obscuring abdominal or pelvic pathology. When abdominal assessment is the primary clinical objective, some centres advise temporary discontinuation of metformin 48–72 hours before the scan, although this practice must be balanced against the risk of glucose dysregulation and should be discussed with the patient’s diabetes care team.

Recent chemotherapy can cause both false-negative results (due to reduced metabolic activity in treated tumour) and false-positive results (due to post-treatment inflammation, bone marrow rebound, and immunological flare). Most guidelines recommend waiting at least 2–3 weeks after the last chemotherapy cycle before performing an interim or end-of-treatment FDG PET scan. For immunotherapy response assessment, the situation is more complex, as pseudoprogression (initial apparent increase in tumour burden followed by subsequent response) can occur and must be differentiated from true progression.

What Is the Correct Dosage of Fludeoxyglucose (18F)?

Fludeoxyglucose (18F) is administered as a single intravenous injection, typically into an antecubital vein. The injection should be given slowly and the integrity of the venous access must be confirmed to avoid paravenous injection, which can cause local radiation exposure to the injection site tissues and may produce false-positive findings in PET images (particularly when scanning the arm or axillary region). The administered activity is measured in megabecquerels (MBq), a unit of radioactivity that quantifies the number of radioactive disintegrations per second.

Adults

Children

Elderly

No specific dose adjustment is required in elderly patients. The standard adult weight-based dosing protocol applies. However, particular attention should be given to ensuring adequate fasting glucose control (diabetic comorbidity is common in the elderly), adequate hydration (elderly patients are more prone to dehydration), and comfortable positioning (to minimize motion during the scan). If sedation is required for positioning reasons, benzodiazepines may affect brain FDG distribution patterns, which should be noted if brain evaluation is part of the examination.

Missed Dose

The concept of a “missed dose” does not apply to fludeoxyglucose (18F) in the conventional sense, as it is a single-dose diagnostic agent administered immediately before a PET scan, not a medication taken on a regular schedule. If the examination cannot proceed as planned (for example, due to equipment failure, unacceptable blood glucose levels, or patient factors), the prepared dose of fludeoxyglucose (18F) cannot be saved for later use because of the short physical half-life of fluorine-18. The radioactivity decays by approximately 50% every 110 minutes, rendering the preparation unusable after a few hours. A fresh dose must be prepared for the rescheduled examination.

Overdose

A true pharmacological overdose is not expected with fludeoxyglucose (18F) because the amount of chemical substance injected is in the nanomolar to micromolar range, far below any pharmacologically active dose. However, administration of an excessive radioactive activity increases the patient’s radiation exposure. If an inadvertent excess of activity is administered, the radiation dose to the patient can be partially mitigated by promoting frequent urination and ensuring generous oral hydration to accelerate renal excretion. Forced diuresis with intravenous fluids may be considered in cases of significant overexposure. The incident should be documented and reported according to local radiation protection regulations.

What Are the Side Effects of Fludeoxyglucose (18F)?

Fludeoxyglucose (18F) has an excellent safety profile. Because it is administered at sub-pharmacological doses (nanomolar to micromolar concentrations), it has no pharmacological effects and does not elicit dose-dependent toxicity in the traditional sense. The adverse events that have been reported are generally mild and transient. Comprehensive post-marketing surveillance data from millions of FDG PET examinations performed worldwide confirm the very low incidence of adverse reactions.

The following side effect frequency categories are based on the European Medicines Agency (EMA) classification system and reflect data from clinical trials, post-marketing reports, and published pharmacovigilance literature.

Radiation Exposure Considerations

The most significant safety consideration associated with FDG PET is the radiation exposure from both the injected radiotracer and, in the case of PET/CT, the CT component of the examination. The effective radiation dose from the FDG component alone is approximately 5–7 mSv for a standard administered activity in an adult. The CT component adds an additional 2–20 mSv depending on the protocol used (low-dose CT for attenuation correction versus diagnostic-quality CT). For context, the average annual background radiation dose from natural sources is approximately 2.4 mSv worldwide.

The radiation dose from FDG PET is considered to be in the low-dose range and is associated with a very small (and largely theoretical) increase in lifetime cancer risk. The International Commission on Radiological Protection (ICRP) estimates that the lifetime excess cancer risk from a radiation dose of 10 mSv is approximately 0.05% (1 in 2,000), which is negligible compared with the baseline lifetime cancer risk of approximately 40%. Nevertheless, radiation protection principles mandate that every examination must be clinically justified and that the administered activity should be optimized to achieve the required diagnostic image quality with the lowest reasonably achievable radiation exposure.

Patients should be advised that the radiation from the injected FDG will be present in their body for several hours after the examination. Although the levels are low and decline rapidly (the activity halves approximately every 110 minutes), patients should take common-sense precautions such as avoiding prolonged close contact with pregnant women and young children for a few hours after the scan. Most nuclear medicine departments provide specific post-scan radiation safety instructions, and patients should follow these carefully.

How Should Fludeoxyglucose (18F) Be Stored?

Storage and handling of fludeoxyglucose (18F) Alliance Medical is fundamentally different from that of conventional pharmaceuticals because of its radioactive nature. The product must be stored, transported, and handled in compliance with national and international regulations governing radioactive materials, including the IAEA Transport Regulations, European Directive 2013/59/Euratom (Basic Safety Standards), and applicable national legislation.

The product should be stored in its original shielding container (typically made of lead or tungsten) at a temperature below 25°C. It must not be frozen. The product should be stored in a designated radioactive materials storage area within the nuclear medicine department, behind appropriate shielding and with restricted access. All storage and handling should follow the ALARA principle to minimize radiation exposure to staff.

Due to the short physical half-life of fluorine-18 (109.77 minutes, or approximately 110 minutes), the product has a very limited shelf life. The expiry time is specified on the product label and typically ranges from 8 to 16 hours from the time of manufacture, depending on the initial radioactive concentration. After the expiry time, the product must be disposed of as radioactive waste according to local regulations, even if the vial still contains solution. The radioactive concentration at any given time can be calculated using the standard radioactive decay formula.

Patients do not store or handle this product at any point. Fludeoxyglucose (18F) is exclusively prepared, quality-controlled, and administered within the nuclear medicine department. Patients should not be concerned with storage requirements, but may find it helpful to understand that the product is manufactured fresh (often on the same day it is used) and undergoes rigorous quality control testing before administration, including checks for radionuclidic purity, radiochemical purity, pH, sterility, and bacterial endotoxin content.

Keep out of the sight and reach of children. This instruction applies to the nuclear medicine department setting, where appropriate access controls and radiation protection measures must be in place to prevent unauthorized access to radioactive materials.

What Does Fludeoxyglucose (18F) Alliance Medical Contain?

Fludeoxyglucose (18F) Alliance Medical is a sterile radiopharmaceutical preparation supplied as a clear, colourless to slightly yellow solution for intravenous injection. Each vial contains fludeoxyglucose (18F) at a radioactive concentration of 300 MBq/mL to 3100 MBq/mL at the date and time of calibration specified on the label. The chemical name of the active substance is 2-deoxy-2-[¹⁸F]fluoro-D-glucose, and its molecular formula is C₆H₁₁¹⁸FO₅.

The excipients (inactive ingredients) in the formulation are:

• Sodium chloride: Used to adjust the tonicity (osmolarity) of the solution so that it is compatible with intravenous injection and does not cause damage to red blood cells.
• Sodium citrate: Acts as a buffering agent to maintain the pH of the solution within an acceptable range.
• Citric acid: Used together with sodium citrate as part of the citrate buffer system to stabilize the pH.
• Water for injections: The solvent for the preparation, meeting pharmacopoeial standards for injectable water.

The solution is presented in multi-dose glass vials sealed with rubber closures and aluminium caps. The glass vials are placed within lead or tungsten shielding containers to reduce external radiation exposure during transport and handling. Each vial contains enough solution for multiple patient doses, depending on the volume and radioactive concentration at the time of use.

The total mass of fludeoxyglucose in each dose is extremely small — typically in the nanogram to microgram range. This is because the specific activity (radioactivity per unit mass) of fluorine-18 labelled compounds is very high, meaning that only a tiny amount of chemical substance is needed to achieve the required radioactive activity for imaging. At these trace quantities, fludeoxyglucose has no pharmacological effect on glucose metabolism or any other physiological process.

Quality control testing is performed on each batch before release for patient use. This includes verification of radionuclidic purity (confirming that the radioactivity is due to fluorine-18 and not other radionuclides), radiochemical purity (typically >95% as fludeoxyglucose (18F)), pH (typically 4.5–8.5), sterility testing, bacterial endotoxin testing, and residual solvent analysis. The production of fludeoxyglucose (18F) requires a cyclotron facility capable of producing fluorine-18 by proton bombardment of oxygen-18 enriched water, followed by radiochemical synthesis using automated modules in compliance with Good Manufacturing Practice (GMP) standards.