PET CT can show active inflammation in the walls of large arteries in giant cell arteritis and Takayasu arteritis. Learn when it is useful and what it shows.
Large vessel vasculitis (such as giant cell arteritis and Takayasu arteritis) is inflammation of the walls of big arteries like the aorta and its branches. PET CT shows which arteries are inflamed and how active the disease is, and helps when fever, weight loss or pain has no clear cause. It is used with blood tests, ultrasound, CT or MR angiography and clinical examination.
Why Large Vessel Vasculitis Is Hard to Spot
Symptoms may be vague: fever, tiredness, weight loss, arm or leg pain on use, headache, blood pressure differences between arms and absent pulses. Blood tests such as ESR and CRP are raised but not specific. Imaging shows the arteries and helps confirm the diagnosis. See PET CT for fever and infection.
ConditionWho is usually affectedPET CT may showGiant cell arteritisOlder adults, headache, jaw pain, vision lossInflamed aorta and branches, temporal arteries (limited)Takayasu arteritisYoung women, weak pulses, arm painActive inflammation along the aorta and its branchesPolymyalgia rheumaticaShoulder and hip stiffnessInflamed shoulders and hipsAortitis from other causesVariedAortic wall uptakeWhat PET CT Shows
PET CT shows increased FDG uptake along the walls of inflamed arteries, such as the aorta, subclavian and carotid arteries. The CT part can show wall thickening or narrowing. It is most useful in active disease and before steroids are started or early in treatment, since steroids reduce uptake.
Other Tests in the Work-Up
- CT angiography or MR angiography for narrowing and aneurysms. See CT angiography vs MR angiography
- Doppler ultrasound of temporal and neck arteries. See carotid Doppler
- Temporal artery biopsy in suspected giant cell arteritis
- Blood tests including ESR, CRP and TB screening in India
Preparation
Fast for 4 to 6 hours and control blood sugar. Tell the staff if you are on steroids and for how long, since this affects results. Rest quietly after the injection. Bring blood reports and any earlier scans. See PET CT preparation.
Limits
Atherosclerosis (fatty plaque) can also take up the tracer, usually less and in a patchy pattern. After steroids, uptake falls. Small vessels in the head, such as temporal arteries, are poorly seen on PET CT. The report is read by a nuclear medicine specialist with the clinical details.
A Practical Example
Aarti, 29, has had fever, weight loss and pain in her left arm while working. Blood pressure differs between her arms, and her ESR is high. A PET CT shows active inflammation along the aorta and left subclavian artery. A rheumatologist starts steroids and other medicines, and a follow-up scan after months shows reduced activity.
After the Scan and Next Steps
Take the report to a rheumatologist. Treatment uses steroids and medicines that calm the immune system, along with regular follow-up of symptoms, blood tests and imaging. Take medicines exactly as prescribed, protect your bones, control blood pressure and report vision loss, severe headache or new limb pain urgently.
Questions to Ask Your Doctor
- Which arteries are inflamed and how active is the disease?
- Do I need CT or MR angiography as well?
- How long will I need steroids?
- How will we judge treatment response?
Common Mistakes to Avoid
- Stopping steroids suddenly.
- Not telling the team you are already on steroids.
- Ignoring sudden vision loss or severe headache.
Booking, Timing and Report
Ask your doctor for the best timing of the scan. Book a morning slot so that fasting is easier, arrange someone to accompany you, and allow 2 to 3 hours at the centre. Carry biopsy, scan and blood reports and a medicine list. Reports are usually ready within 24 to 48 hours, and images can be given on a CD or digital link for your doctor.
Frequently Asked Questions
What is large vessel vasculitis?
Inflammation of large artery walls.
Can PET CT diagnose it?
It supports the diagnosis along with other tests.
Why do steroids affect the scan?
They reduce inflammation and uptake.
What is Takayasu arteritis?
Vasculitis mainly of the aorta and its branches, often in young women.
Do I need fasting?
Yes, 4 to 6 hours.
Is a biopsy needed?
Sometimes, for temporal arteries.
Can it be treated?
Yes, with steroids and other medicines.
How long does the scan take?
About 2 to 3 hours.
When is the report ready?
Usually 24 to 48 hours.
Book Your Test at Ganesh Diagnostic
Ganesh Diagnostic & Imaging Centre in Rohini, Delhi offers this test with trained radiology staff and clear reports. You can book an appointment online, check our branches across Delhi NCR, contact us for current rates, or explore all our services. Reports can be downloaded online through our patient portal, so you do not need to make a second trip just to collect them.
This article is for general information only. It does not replace advice from your doctor. Always follow your doctor's instructions for your test.
