SPECT-CT Scans of the Spine

By Mr Ahmed-Ramadan Sadek, Neurosurgeon · Last reviewed October 2026 · 7 min read

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On this page

What a SPECT-CT scan is
How the tracer works
When it is used in spinal care
Before your scan
What the day involves
How much radiation is involved?
After the scan
Further reading

Key points

SPECT-CT combines a nuclear medicine bone scan, which shows how active the bone is, with a CT scan, which shows its exact shape.
It can help to pinpoint which part of the spine is likely to be causing pain when other scans show several possible culprits.
It is used to look for painful facet joints, stress fractures of the pars and problems after fusion surgery, such as loose screws.
Expect the visit to take 3 to 4 hours in total, including a wait of 2 to 3 hours between the injection and the scan.
Tell the department beforehand if you are, or could be, pregnant, or if you are breastfeeding.

What a SPECT-CT scan is

Most scans of the spine, such as X-ray, CT and MRI, show structure: what the bones and soft tissues look like. A bone scan shows something different. It looks at how active the bone cells are. Bone is constantly being broken down and rebuilt, and in some conditions this process speeds up in one spot.^[1] That busy area shows up as a bright patch, often called a hot spot.

SPECT stands for single photon emission computed tomography. It is a way of taking the bone scan pictures in three dimensions. On its own, though, a bone scan is not very precise about location. Adding a CT scan in the same session lets the two sets of images be laid on top of each other, so a hot spot can be matched to an exact joint or part of a vertebra.^[1]

How the tracer works

You are given an injection of a small amount of a radioactive substance, called a tracer, into a vein in your arm or hand. Over the next few hours it is taken up by the bones, with more going to areas where bone turnover is high.^[1,2] A special camera called a gamma camera then detects the tracer and builds the pictures. This can reveal problems that do not show on ordinary X-rays.^[2]

When it is used in spinal care

SPECT-CT is not a first-line test. It tends to be used when the cause of pain is still unclear after an examination and an MRI, or when there are several areas of wear and the question is which one matters.

Facet joint pain

The facet joints are the small paired joints at the back of the spine. Wear in these joints is very common, so an MRI often shows changes at several levels. A 2023 systematic review found that people whose facet joints were active on SPECT tended to get more benefit from facet joint injections, and concluded that SPECT-CT may be useful when findings are unclear or there are multiple degenerative changes.^[3]

The evidence is not entirely consistent. A 2025 review of six studies, involving 308 patients, found that a positive SPECT scan predicted a better response to facet joint injections, especially injections directly into the joint. For SPECT-CT specifically, however, the results were inconclusive, and the authors advised caution because the studies were small and observational.^[4]

Pars stress fractures

Spondylolysis is a stress fracture of the pars, a thin bridge of bone at the back of the vertebra, and is a common cause of back pain in young athletes. A 2015 review described SPECT-CT as well suited to assessing back pain in children and young adults, because it can show whether a pars fracture is active and how likely it is to heal.^[5] A 2024 analysis of eight studies (785 patients) found that SPECT correctly picked up about 85 in 100 cases of spondylolysis and correctly ruled it out in about 92 in 100 people without it. It was better at ruling the condition out in children and teenagers than in older adults.^[6]

Pain after spinal surgery

Ongoing or new pain after a spinal fusion can be hard to explain, and standard scans do not always give a clear answer. A 2024 systematic review found that SPECT-CT and a related scan, PET-CT, were useful for assessing pain after spinal surgery, including detecting loose screws and a fusion that has not knitted together, particularly when standard imaging was inconclusive. The authors called for better studies comparing these scans with conventional imaging.^[7]

Before your scan

Preparation is simple. You can usually eat and take your normal medicines. One hospital, for example, asks patients to drink plenty of water from the afternoon before.^[1] Wear loose, comfortable clothing; you will not usually need to undress, but you will be asked to remove metal items such as jewellery and belts.^[1,2]

Contact the nuclear medicine department before your appointment if you:

are, or might be, pregnant. Radiation can harm an unborn baby, and a non-urgent scan can be postponed
are breastfeeding, as you may be given special instructions
are incontinent, use a catheter or need a hoist
have been told to limit how much you drink
think you will struggle to lie still for up to an hour

This list is based on NHS hospital patient information.^[1,2]

Hospitals generally ask you not to bring babies or young children to the appointment, so plan childcare in advance.^[1,2]

What the day involves

The injection. The tracer is injected into a vein in your arm or hand. It feels much like a blood test, and the tracer itself has no side effects.^[1,2]
The wait. The tracer needs 2 to 3 hours to be taken up by the bones. You can often leave the department during this time. Drink plenty of fluid and empty your bladder often, which gives clearer pictures and helps clear the tracer.^[1]
The scan. You empty your bladder, then lie on your back on a couch. The gamma camera is not a tunnel, but its detectors come close to your body. Scanning usually takes 45 to 60 minutes, sometimes longer if more than one area is imaged, and you need to keep still.^[1]

Allow 3 to 4 hours for the whole visit.^[1] The scan does not affect your ability to drive afterwards.^[2]

How much radiation is involved?

We all receive natural background radiation, on average about 2.1 millisieverts (mSv) a year in the UK.^[8] The table shows figures from the UK Health Security Agency (UKHSA).

Test (UKHSA figures)	Typical dose	Similar to natural background over
Chest X-ray (single film)	0.02 mSv	3 days
Lumbar spine X-ray	1.3 mSv	7 months
Bone scan (tracer injection)	4 mSv	2 years
CT abdomen and pelvis (for comparison)	10 mSv	4.5 years

The bone scan figure covers the tracer. The CT part of a SPECT-CT adds to this, with the amount depending on the area scanned. UKHSA estimates the extra lifetime risk of fatal cancer from a bone scan at about 1 in 5,000 for adults aged 16 to 69, and around five times lower in older people.^[8] The Royal National Orthopaedic Hospital describes the overall dose from SPECT-CT as small, similar to a CT scan, and says a doctor checks every request to make sure the benefit outweighs the risk.^[1]

After the scan

A small amount of radioactivity stays in your body for a short time. It fades quickly, and drinking plenty helps. Advice on close contact varies between hospitals. One asks you to keep time with pregnant women, babies and small children as short as possible for the rest of the day, while still giving children essential care.^[1] Another suggests avoiding prolonged close contact, such as a child sitting on your lap for more than 30 minutes, for 24 hours.^[2] Follow the instructions your own department gives you.

Airport radiation detectors are very sensitive. If you are travelling abroad within a week, take your appointment letter with you in case it sets off an alarm.^[1]

A specialist doctor reports the scan, and the report usually goes to the doctor who requested it rather than to your GP.^[1] One hospital advises allowing two weeks for results.^[2] A hot spot is a clue rather than a final answer, so your specialist will put it together with your symptoms, examination and other scans before suggesting treatment.