Giant Cell Arteritis and PET Scan (GAPS) Study

Study Overview
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Brief Summary
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Giant cell arteritis (GCA) is a medium to large vessel vasculitis with a predilection for the superficial cranial and intrathoracic arteries. Diagnosing the condition and predicting which patients will develop large vessel complications remains a challenge. There are limitations with temporal artery biopsy, magnetic resonance angiography and ultrasound of temporal arteries and American College of Rheumatology classification criteria. Positron emission tomography (PET) has been shown to be a useful modality in detecting inflammation in large intra-thoracic vessels but previously has not been able to accurately detect FDG uptake in the superficial cranial arteries due to poor spatial resolution. Newer scanners can perform finer cuts of the head and can detect uptake in these arteries. This study has three main components: Cross sectional study assessing the accuracy of PET uptake in the superficial cranial and intrathoracic arteries of suspected GCA patients for the diagnosis of GCA Cohort study assessing the prognostic implication of FDG aortic uptake on aortic diameter at 24 months Cohort study assessing the Th1 and Th17 cytokine profile in patients with and without FDG PET uptake at 0, 6 and 24 months

Official Title
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Giant Cell Arteritis and PET Scan (GAPS) Study - Improving the Diagnosis and Prognostication of Giant Cell Arteritis Through the Novel Use of Positron Emission Tomography and Immune Biomarkers

Conditions
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Giant Cell Arteritis

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Rheumatologist, neurologist or ophthalmologist suspect diagnosis of GCA Age > 50 Meet at least 2 of 1990 American College of Rheumatology classification criteria for GCA Age >= 50 ESR >= 50 New onset localised headache Temporal artery abnormality (tenderness or decreased pulsation) Positive biopsy (will not be available at time of enrolment) Exclusion Criteria: Corticosteroid therapy for > 72 hours before first PET scan Prolonged corticosteroid therapy (> 1 week) for another indication in past 6 months History of vasculitis or connective tissue disease Active malignancy

Ages Eligible for Study
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Minimum Age: 50 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Suspected GCA (GCA final diagnosis)<br> | |
| Suspected GCA (alternative final diagnosis)<br> | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Diagnostic accuracy of FDG uptake in the superficial cranial or intrathoracic arteries for the diagnosis of temporal artery biopsy proven GCA amongst patients with suspected GCA |  | Baseline | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Difference in aortic diameter at 24 months between patients with and without PET scan aortic uptake at time 0. |  | 24 months | 
| Difference in Th1 and Th17 axis cytokines in patients with and without thoracic large vessel PET uptake at 0, 6 and 24 months |  | 24 months | 
| Prevalence of varicella zoster virus antigen and DNA in temporal artery biopsy GCA specimens |  | 24 months | 
| Prevalence of acute varicella zoster IgM serology positivity in biopsy confirmed GCA patients |  | 24 months | 
| Difference in combined vascular events between GCA patients with and without thoracic large vessel PET uptake at 0, 6 and 24 months |  | 24 months | 
| Difference in temporal artery histology between GCA patients with and without thoracic large vessel PET uptake at 0 months |  | Baseline | 
| Difference in temporal artery histology between GCA patients with and without temporal artery PET uptake at 0 months |  | Baseline |