Is there a role for routine positron emission tomography (PET) scans in stable patients with giant cell arteritis?
There is uncertainty as to whether GCA patients should undergo routine vascular screening at 6 months (by PET scan or ultrasound) to ensure the disease is well controlled. This paper from our team at Royal North Shore Hospital was published in April 2020. The findings are from a group of 21 GCA patients who had a PET scan at both diagnosis and at 6 months. The 6 month scan was conducted while they were on stable treatment.
The study had two main findings:
1) PET scan activity was lower at 6 months than at diagnosis for all blood vessel regions.
2) Some patients feel well at 6 months but have moderate ongoing PET scan blood vessel activity. These patients did not have a relapse (return of GCA symptoms) in the following months or require increased treatment.
This study indicates that ongoing blood vessel activity on PET scan at 6 months does not, in its own right indicate a need to increase treatment. Based on this I will continue to use PET scan for new GCA patients but will not perform routine follow-up scans for stable patients.
It is important to note that follow-up PET scans may still be useful for individual patients, particularly those with unexplained high blood markers, ongoing symptoms, or progressive blood vessel thickening (stenosis) or widening (aneurysm). An active PET scan in these circumstances may indicate a need to increase treatment.