Gallium Scan (Gallium-67 Scintigraphy): Uses, Preparation, Timing and Limitations

Key takeaways

• The gallium scan shows where inflammatory or tumour activity may be, not what is causing it.
• Imaging is spread over 24 to 72 hours after injection, so the gallium scan is a multi-visit test, not a single sitting.
• Gallium-67 uptake is non-specific: infection, inflammation, healing tissue and some tumours can all appear as hot spots.
• A normal gallium scan does not exclude infection or malignancy, particularly if imaging was done too early or antibiotics have already been started.
• In most Indian centres, FDG PET-CT and labelled-leucocyte scans have replaced the gallium scan for many indications; the gallium scan remains useful in selected cases.

At a glance

Also known as

• Gallium-67 scan, Ga-67 scan
• Gallium scintigraphy, gallium citrate scan
• Gallium imaging or "gallium whole body scan"
• Commonly described in Indian hospitals as a "nuclear scan" or "nuclear medicine scan", a broad term that also covers bone scans, thyroid scans and PET scans, which are different tests

What a gallium scan is

Gallium-67 citrate behaves in the body somewhat like iron. After intravenous injection, gallium-67 binds to transferrin and other iron-binding proteins, and tends to concentrate where there is increased vascular permeability, leucocyte activity or rapid cellular turnover. That is why inflamed, infected and some tumour tissues show higher gallium uptake than surrounding tissue.

Gallium-67 has a physical half-life of about 78 hours and emits gamma photons at several energies. The long half-life is what allows delayed imaging at 24 to 72 hours, and it is also why the radiation dose from a gallium scan is higher than from many other nuclear medicine studies.

Normal gallium distribution includes the liver, spleen, bone marrow, nasopharynx, lacrimal glands, breast tissue and bowel. Reporting depends on recognising these normal patterns, which is one reason the gallium scan must be read by a nuclear medicine physician.

Why a gallium scan is done

• Occult infection or fever of unknown origin: as a whole-body survey when the site of infection is not clear.
• Chronic osteomyelitis and suspected spinal infection: often combined with a technetium-99m bone scan, because gallium uptake in bone can be interpreted alongside bone-scan uptake.
• Sarcoidosis: to assess extent and activity of disease; patterns such as bilateral hilar and parotid or lacrimal uptake have been described in sarcoidosis, but these patterns are suggestive rather than diagnostic.
• Interstitial lung disease and selected inflammatory lung conditions: to gauge activity of alveolitis in some protocols.
• Lymphoma: historically used for staging and treatment response, now largely replaced by FDG PET-CT.
• Response assessment: repeat imaging to see whether previously abnormal uptake has reduced after treatment.

Who should get this test

A gallium scan is not a screening test and is not ordered on patient request. A nuclear medicine physician, infectious disease specialist, rheumatologist, pulmonologist, orthopaedic surgeon or oncologist may consider it when:

• Prolonged fever or raised inflammatory markers remain unexplained after history, examination, cultures, and CT or ultrasound.
• Chronic bone or joint infection is suspected and plain radiographs or MRI are inconclusive, or MRI cannot be done because of metallic hardware artefact or an implant that has not cleared MRI safety assessment.
• Sarcoidosis or another granulomatous or inflammatory disease needs whole-body mapping of activity.
• FDG PET-CT is unavailable, unaffordable, or unsuitable for the clinical question, and a gallium scan can still answer it.

Who generally should not have a gallium scan, or needs specific counselling first: people who are pregnant or may be pregnant, women who are breastfeeding, and young children, in each case the radiation dose and alternative tests must be discussed. Results vary depending on individual clinical circumstances.

What a gallium scan cannot detect or exclude

• It cannot tell infection from inflammation from tumour. Gallium uptake indicates activity, not cause. A hot spot may be an abscess, active sarcoidosis, a healing fracture, recent surgery, radiation change, or lymphoma.
• It cannot reliably exclude infection. If antibiotics have already been given, or imaging is performed too early, or the focus is small, the gallium scan may be negative while infection is present.
• It does not provide detailed anatomy. Spatial resolution is limited. The gallium scan does not replace CT or MRI for defining an abscess cavity, disc space, soft tissue plane or surgical approach. SPECT-CT improves localisation but the CT component is typically low-dose and for localisation rather than full diagnostic reporting.
• It does not reliably show abdominal and pelvic pathology because gallium is excreted into the bowel; normal colonic activity can hide or mimic disease.
• It is insensitive to many brain, bladder and small bowel lesions and is not used for coronary, cardiac or vascular assessment.
• It does not grade severity or give a tissue diagnosis. Biopsy, culture or histopathology remains necessary when a definite diagnosis is required.
• It is not a substitute for blood cultures in suspected bloodstream infection.

A gallium scan reported as showing "no abnormal uptake" means abnormal uptake was not identified on the images obtained. That is not the same as a condition being excluded. If symptoms persist or worsen despite a normal gallium scan, go back to the doctor who requested the test.

Related but different examinations

These tests are often confused with a gallium scan. They answer different questions and are not interchangeable.

The frequent confusion worth correcting: a "gallium scan" (gallium-67 citrate, gamma camera, 2 to 3 days) is not the same as a "Ga-68 PET scan" (gallium-68 labelled tracer, PET-CT, same day). If a report or prescription is unclear, ask the nuclear medicine department which tracer is intended.

Which test comes first depends on the clinical problem

• Suspected prosthetic joint infection: plain radiographs, joint aspiration and culture usually come first; labelled-leucocyte imaging with a bone marrow scan is often preferred over a gallium scan.
• Suspected vertebral osteomyelitis or discitis: MRI of the spine is generally the preferred first imaging test; a combined bone and gallium study is an option when MRI is inconclusive or cannot be performed.
• Fever of unknown origin: history, examination, cultures, targeted serology and CT usually come first; FDG PET-CT, where available, is generally preferred over a gallium scan.
• Suspected sarcoidosis: chest imaging, lung function tests, serum calcium and biopsy drive the diagnosis; gallium or FDG imaging assesses extent and activity.
• Lymphoma staging or response: FDG PET-CT is the current standard for most FDG-avid lymphomas.

How to prepare for a gallium scan

Preparation is a unit-specific operational matter. Protocols differ between nuclear medicine departments, and written instructions from the department performing your gallium scan take precedence over anything on this page.

• Medicines: bring a complete list, including antibiotics, steroids, other immunosuppressants, chemotherapy, iron supplements or recent blood transfusion, all of which can alter gallium uptake. Do not stop or change any prescribed medicine yourself, ask the prescriber and the nuclear medicine team.
• Recent procedures: report recent surgery, biopsy, drain insertion, injections, fracture, radiotherapy or a recent barium study or other nuclear scan.
• Fasting: fasting is usually not required for a gallium scan, but some units ask for it if other tests are combined. Follow your unit's instruction.
• Bowel preparation: because gallium is excreted through the bowel, some departments prescribe a laxative or enema before abdominal imaging. This is unit-specific and should not be self-administered.
• Fluids: many units advise drinking water normally after the injection to help clearance. If you have heart failure, advanced chronic kidney disease, dialysis dependence or any prescribed fluid restriction, do not increase fluid intake without checking with your treating doctor.
• Clothing and metal: wear comfortable clothing and expect to remove jewellery, coins, belts and metal objects, which cause attenuation artefacts.
• Plan your time: the gallium scan requires you to come back on later days. Arrange transport and leave in advance.

Pregnancy and possible pregnancy

Tell the department before injection if you are pregnant or your period is late. Gallium-67 crosses the placenta and the study is generally avoided in pregnancy; the referring doctor and nuclear medicine physician will weigh alternatives such as MRI or ultrasound.

Breastfeeding

Gallium-67 is secreted into breast milk and the long half-life means a prolonged interruption of breastfeeding may be advised. Ask the nuclear medicine physician for the specific interval and plan expressed milk storage in advance.

Children

Paediatric gallium scans use weight-adjusted activity and are undertaken only when the information cannot be obtained with a lower-dose or non-radiation test. Long imaging times may need play preparation or, occasionally, sedation.

Kidney disease, dialysis and heart failure

Gallium-67 citrate is not iodinated contrast and does not carry contrast-nephropathy risk. However, reduced renal clearance alters tracer distribution and image timing, and hydration advice must be individualised. Tell the department if you are on dialysis so imaging can be scheduled around sessions.

Diabetes on glucose-lowering treatment

If your unit asks you to fast for a combined study, ask the prescriber how to handle insulin or other glucose-lowering medicines that day, and carry a glucose source.

Older adults and people with reduced mobility

Lying still for prolonged imaging can be uncomfortable. Tell the staff about back pain, tremor, breathlessness on lying flat or continence concerns so positioning and breaks can be planned.

What happens during a gallium scan and how long the process takes

• Day 1, injection: gallium-67 citrate is injected into an arm vein. This takes a few minutes. There is no sensation of heat or flushing as with iodinated contrast. You can usually go home and eat and drink normally.
• Waiting period: gallium needs time to clear from the blood and accumulate at abnormal sites. Most protocols image at 24 hours, then again at 48 hours, and sometimes 72 hours. Occasionally early images at 4 to 6 hours are added.
• Imaging sessions: you lie on a bed while a gamma camera moves slowly over you. Whole-body planar imaging usually takes about 30 to 60 minutes; adding SPECT or SPECT-CT of a region adds roughly another 20 to 40 minutes. The camera does not enclose you fully like an MRI tunnel, and it makes little noise.
• Total elapsed time: from injection to the last images, a standard gallium scan spans two to three days, with only a few hours actually spent in the department on each visit.
• Afterwards: no recovery period is needed and you can drive and return to work. Staff may give simple radiation-safety advice, such as flushing the toilet and washing hands, and advice on close contact with infants or pregnant household members for a defined period. Follow the written instructions your unit gives you.

Reporting time: the final report can only be issued after the last imaging session, so it is never available on the day of injection. Ask your nuclear medicine department for their reporting schedule.

Understanding your gallium scan report

A nuclear medicine physician compares the pattern, intensity and change over time of gallium uptake against expected normal distribution. Typical report language includes:

• No abnormal focal tracer uptake: the distribution seen matches expected physiological uptake. This does not exclude disease, especially in the abdomen or if treatment was already started.
• Focal increased uptake: a discrete hot spot. The report will usually suggest possible explanations and recommend anatomical correlation with CT, MRI or ultrasound, or a biopsy or culture.
• Diffuse pulmonary uptake: may be seen in interstitial inflammation or infection, but also after chemotherapy, radiation or drug reactions.
• Bilateral hilar or salivary and lacrimal uptake: described in sarcoidosis, though not unique to it.
• Reduced uptake compared with a previous gallium scan: may indicate treatment response, but timing, dose and camera settings must be comparable.

The gallium scan does not make a diagnosis on its own. Only the doctor who requested it, reading it together with your symptoms, examination, blood tests, cultures and other imaging, can say what the finding means for you.

When gallium scan results can be misleading

Causes of falsely increased or misleading uptake

• Recent surgery, biopsy, drain or catheter site, or a healing fracture.
• Intramuscular injection sites and cannula-related phlebitis.
• Radiotherapy change and post-chemotherapy thymic or marrow rebound.
• Normal bowel excretion mimicking abdominal infection, and constipation increasing retained activity.
• Recent blood transfusion, iron therapy or iron overload altering transferrin-bound tracer distribution.
• Breast uptake in pregnancy, lactation or with some drugs; nasopharyngeal and lacrimal uptake as a normal variant, including after viral upper respiratory infection.
• Renal uptake, which is normal within the first 24 hours but abnormal if persistent, mistiming imaging can therefore produce an incorrect impression.

Causes of falsely reduced or absent uptake

• Antibiotics, corticosteroids or other immunosuppressants started before the gallium scan, which can blunt inflammatory uptake.
• Imaging performed too early, before adequate blood-pool clearance.
• Lesions that are small, walled off, or poorly vascularised.
• Tumours that are not gallium-avid, many solid cancers show little or no gallium uptake, so a gallium scan is not a general cancer-screening test.
• Lesions overlying or adjacent to liver, spleen, marrow or bowel, where high background activity masks them.
• Very high body habitus attenuation or patient movement degrading image quality.

Risks and safety

Different nuclear medicine studies carry different radiation doses; safety statements cannot be generalised across the whole family of "nuclear scans".

Radiation exposure

A gallium-67 scan involves ionising radiation and, because of the long physical half-life and multiple gamma energies, its effective dose is generally higher than that of common studies such as a technetium-99m bone scan. The dose is justified only when the clinical question matters and no lower-dose alternative will answer it. In India, medical use of radioisotopes is regulated by the Atomic Energy Regulatory Board, and departments are required to follow dose-optimisation and radiation-protection rules.

Injection-site and reaction risks

Bruising, mild soreness or, uncommonly, extravasation at the injection site can occur. True allergic reactions to gallium-67 citrate are very uncommon. Tell the staff promptly about rash, itching, swelling, wheeze or breathlessness after injection.

Practical and comfort-related risks

Prolonged lying still may worsen back or joint pain. Repeated visits and long waits can be difficult for frail or dependent patients. Radiation-safety instructions about close contact with infants or pregnant women are given because gallium-67 remains detectable in the body for several days.

Pregnancy-related risk

Foetal exposure is the principal reason gallium imaging is avoided in pregnancy unless there is a compelling indication and no alternative.

Results and risk profiles vary depending on individual clinical circumstances.

Special situations

People living with HIV

Gallium imaging has historically been used in HIV-associated pulmonary and systemic infections and in some lymphomas. The interpretation depends heavily on CD4 count, current antiretroviral and prophylactic therapy, and coexisting tuberculosis.

Tuberculosis and granulomatous disease

In India, tuberculosis is a common cause of gallium-avid lesions in lung, lymph nodes, spine and abdomen. Gallium uptake cannot distinguish tuberculosis from sarcoidosis, lymphoma or fungal disease; microbiological or histological confirmation is required before starting anti-tubercular therapy.

People with metallic implants

Because MRI around metal may be degraded by artefact, and some implants require formal MRI safety assessment, nuclear imaging including a gallium scan is sometimes chosen instead. Metal does not interfere with gallium uptake, though it can cause attenuation on images.

Children and adolescents

Radiation-dose sensitivity is higher in children. Ultrasound, MRI and targeted microbiology are preferred where they can answer the question.

Older adults with multiple conditions

Multiple visits, prolonged immobility and transport needs should be factored in when deciding between a gallium scan and a single-visit alternative such as FDG PET-CT.

The gallium scan in the Indian context

• Availability: gallium-67 citrate has limited and variable supply in India, and many nuclear medicine departments now perform few gallium scans. Confirm availability and isotope supply before travelling, as the test may need to be scheduled around delivery of the radiopharmaceutical.
• Regulation: radiopharmaceutical use, storage and disposal are governed by the Atomic Energy Regulatory Board, and only licensed facilities with qualified nuclear medicine physicians and radiation safety officers can perform the study.
• Disease mix: tuberculosis, enteric and other chronic bacterial infections, melioidosis in some regions, fungal infection in people with diabetes, and rheumatic and inflammatory disease all influence how gallium findings are interpreted here.
• Anaemia and iron therapy: iron-deficiency anaemia and iron supplementation are very common in India, and iron status and recent transfusion can affect transferrin-bound gallium distribution, tell the department about both.
• Practical substitution: in many Indian tertiary centres FDG PET-CT is now more readily available than gallium-67, is completed in a single day, and answers most oncological and many infection questions better; labelled-leucocyte imaging is used for pyogenic infection where facilities exist.
• Language and consent: ask for instructions in a language you read comfortably, and confirm who will explain the report to you.

Cost and insurance in India, and what affects the price

Charges for a gallium scan vary widely across cities, between government and private hospitals, and with isotope availability. Prices are not standardised, so ask the nuclear medicine department for a written estimate covering all visits before booking.

Factors that influence the cost of a gallium scan in India:

• Cost and supply of gallium-67 citrate, which is imported or centrally produced and dose-dependent.
• Number of imaging sessions and days of imaging requested.
• Whether SPECT or SPECT-CT is added to planar whole-body imaging.
• Whether a complementary technetium-99m bone scan or labelled-leucocyte scan is performed alongside.
• City, hospital category and whether the facility is government, trust-run or corporate.
• Inpatient versus outpatient status, and whether admission, transport or sedation is needed.
• Separate charges for nuclear medicine physician reporting, consumables and repeat visits.

Insurance points worth checking: nuclear imaging is usually reimbursed when done as part of an admitted hospitalisation with a documented clinical indication, while outpatient diagnostic imaging is often covered only under specific OPD benefits or government schemes. Confirm pre-authorisation requirements with the hospital's insurance desk and your insurer before the injection, since the cost is incurred on day one even if later sessions are missed.

Myths and facts

Frequently asked questions

Is a gallium scan better than a PET-CT?

Neither test is universally superior. FDG PET-CT gives far better resolution, anatomical correlation and same-day results, and is preferred for most cancer and many infection questions. A gallium scan may still be chosen for selected granulomatous or chronic inflammatory problems, or when PET-CT is unavailable or unsuitable.

Why do I have to come back after 24 and 48 hours?

Gallium-67 needs time to clear from the bloodstream and concentrate at abnormal sites. Imaging too early shows mostly blood-pool activity. Delayed images at 24 to 72 hours give better contrast between abnormal areas and normal tissue, so repeat visits are part of the standard protocol.

Does a gallium scan hurt?

The only discomfort is the needle prick for the intravenous injection. The imaging itself is painless, though lying still for 30 to 90 minutes can be tiring, particularly with back or joint pain. Tell the technologist beforehand so positioning supports and short breaks can be arranged.

Should I stop my antibiotics before the scan?

Do not stop, start or change any prescribed medicine on your own. Antibiotics and steroids can reduce gallium uptake and affect interpretation, so the treating doctor and the nuclear medicine physician together decide whether timing needs adjusting. Carry a full, current medicine list to the department.

Can I have a gallium scan if I am breastfeeding?

Tell the department before the injection. Gallium-67 passes into breast milk and, given its long half-life, a prolonged interruption of breastfeeding may be recommended. The nuclear medicine physician will advise the exact interval and whether an alternative test is preferable for your situation.

Is the radiation from a gallium scan harmful?

A gallium scan uses ionising radiation, and its dose is generally higher than that of several other common nuclear medicine studies. Risk from a single justified scan is considered small, but the test is done only when the clinical information needed cannot be obtained by a lower-dose or radiation-free alternative.

What if my gallium scan is normal but I still feel unwell?

A normal gallium scan means no abnormal uptake was identified on the images taken. It does not prove that nothing is wrong. Return to the doctor who ordered the test; further investigation such as MRI, CT, repeat cultures, serology or biopsy may be appropriate.

Can children have a gallium scan?

Yes, when clearly needed, using weight-adjusted activity. Because children are more sensitive to radiation, ultrasound, MRI and microbiological testing are considered first. Long imaging times may require play preparation, a parent present, or occasionally sedation arranged by the paediatric team.

Can I drive and go to work after the scan?

Yes. A gallium scan requires no sedation in most adults, and there is no recovery period. You can eat, drive and resume normal activity between and after imaging sessions, following any radiation-safety instructions your nuclear medicine department provides in writing.

Sources

• Society of Nuclear Medicine and Molecular Imaging, procedure guidance on gallium-67 scintigraphy and infection or inflammation imaging.
• European Association of Nuclear Medicine, guidelines on imaging of inflammation and infection.
• Atomic Energy Regulatory Board, India, radiation safety requirements for medical use of radioisotopes and nuclear medicine facilities.
• Standard nuclear medicine reference texts on radiopharmaceutical biodistribution, normal gallium-67 distribution and interpretation pitfalls.