Giant cell arteritis (GCA) is the most frequent vasculitis in patients above 50 years of age. The disease has limited mortality, mostly due to the development of aortic aneurysms, leading to dissection and rupture. The probability to develop this complication is 17 x higher at the level of the thoracic aorta and 2,4 x at the level of the abdominal aorta in patients with GCA when compared with a control group. Therefore, follow-up of the aortic diameter in patients with GCA is part of good clinical practice. Previous retrospective research showed a link between FDG-uptake at the level of the thoracic aorta, on positron-emission-tomography (PET) at the time of diagnosis, and the increase of diameter and volume of the thoracic aorta during follow-up (on computed tomography (CT)).

The purpose of this prospective study is to follow-up on the aortic diameter, and to correlate these measures with FDG-PET uptake at diagnosis. Ideally, this would allow us to define a group of patients at high risk to develop an aortic aneurysm, already at the time of diagnosis.

As standard care, all patients with a suspicion of GCA undergo a biopsy of the temporal artery and a PET scintigraphy to evaluate the presence of large vessel vasculitis. Patients with proven GCA on biopsy and/or scintigraphy undergo a computed tomography (CT) of the aorta without the administration of contrast, at diagnosis and yearly thereafter (every 12 +/- 3 months) for 10 years.

Measurements include the diameter of the ascending aorta, aortic arch, descending aorta, suprarenal, juxtarenal and infrarenal aorta, and the volume of the thoracic and the abdominal aorta. These measurements are correlated with FDG-uptake at the level of the aorta on PET-scintigraphy at the time of diagnosis. All patients will be treated according to accepted guidelines and standard care in our center (methylprednisolone started at 32 mg/day, with slowly declining doses until stop after 1 to 1,5 years of treatment).

Inclusion Criteria:

• patients with a first episode of biopsy and/or scintigraphy proven giant cell arteritis
• patients with a previous diagnosis of giant cell arteritis, in whom a yearly computed tomography of the aorta is available can opt to participate in this study
• informed consent form has to be signed by all patients

Exclusion Criteria:

• patients already treated with steroids before performance of PET-scintigraphy
• earlier episodes of giant cell arteritis, without documentation of the aortic diameter at that moment

Proven Giant Cell Arteritis