Diagnostic Accuracy of FDG PET/CT of Cranial Arteries in GCA

Study Overview
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Brief Summary
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A case-control study to evaluate the diagnostic accuracy of FDG uptake in cranial arteries by FDG PET/CT in the diagnosis of giant cell arteritis.

Detailed Description
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Although older studies argue that FDG PET/CT cannot demonstrate inflammation in cranial arteries, e.g. temporal and maxillary arteries, the resolution of modern PET systems may have improved, making a case for FDG PET/CT. FDG PET/CT is increasingly used in giant cell arteritis (GCA) diagnosis due to its excellent diagnostic accuracy considering large-vessel involvement. In case of uncommon distribution of vessel involvement or marginally increased large-vessel FDG uptake, FDG PET/CT-specificity may be compromised. Hence, recognising FDG uptake in cranial arteries potentially adds to FDG PET/CTs diagnostic accuracy. Objectives To evaluate the diagnostic accuracy of conventional FDG PET/CT of the cranial arteries in the diagnosis of GCA. Methods In a cohort of consecutively included glucocorticoid-naïve patients suspected of new-onset GCA, patients with a clinical GCA diagnosis will be identified. Conventional FDG PET/CT and vascular ultrasound(US) was performed before treatment. Patients were referred for a temporal artery biopsy (TAB). Controls are age-(+/- 3 years) and sex-matched malignant melanoma (MM) patients who had a follow-up metastatic-disease-free FDG PET/CT ≥6 months after MM resection. Images will be assessed by 5 nuclear medicine physicians blinded to clinical symptoms and findings. Temporal (TA), maxillary (MA) and vertebral (VA) arteries will be visually assessed. Arterial FDG uptake more than FDG uptake in surrounding tissue is considered positive. Sensitivity, specificity and interreader agreement will be evaluated.

Official Title
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Conventional FDG PET/CT Accurately Diagnoses Temporal Arteritis in Glucocorticoid-naïve GCA Patients: a Case-control Study

Conditions
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Giant Cell Arteritis

Intervention / Treatment
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* Radiation: FDG PET/CT


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Cases: 1) age ≥50 years, 2) CRP>15mg/l or ESR>40mm/h, 3) either a) cranial symptoms, b) new-onset extremity claudication or c) weight loss >5 kilograms or fever>38oC for >3 weeks and a clinical diagnosis of giant cell arteritis judged by expert rheumatologist. Controls: age-(+/-3 years) and sex-matched malignant melanoma (MM) patients follow-up metastatic-disease-free FDG PET/CT ≥6 months after MM resection Exclusion Criteria: Previous diagnosis of polymyalgia or giant cell arteritis immunosuppresive treatment within last month

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 |
| --- | --- |
| GCA cases<br>In a cohort of patients suspected of GCA based on the following inclusion criteria were 1) age ≥50 years, 2) CRP>15mg/l or ESR>40mm/h, 3) either a) cranial symptoms, b) new-onset extremity claudication or c) weight loss >5 kilograms or fever>38oC for >3 weeks, patients with a clinical diagnosis of GCA is identified. | Radiation: FDG PET/CT<br>* Conventional FDG PET/CT including head in order to asses cranial arteries.<br>* Other names: Inflammatory biomarkers;|
| controls<br>Age-(+/- 3 years) and sex-matched malignant melanoma (MM) patients who had a follow-up metastatic-disease-free FDG PET/CT ≥6 months after MM resection | Radiation: FDG PET/CT<br>* Conventional FDG PET/CT including head in order to asses cranial arteries.<br>* Other names: Inflammatory biomarkers;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| PET positivity | Presence of FDG uptake in temporal, maxillary and/or vertebral arteries assessed in order to evaluate sensitivity and specificity of PET of cranial arteries in the diagnosis of GCA | Time of diagnosis/pre-treatment (cases) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Full-fillment of ACR criteria | PET sensitivity and specificity in the subpopulation of GCA patients full filling ACR criteria | Time of diagnosis | 
| Temporal artery biopsy | Correlation between temporal artery biopsy result and temporal artery FDG uptake | Time of diagnosis | 
| Temporal artery ultrasound | Correlation between temporal artery ultrasound result and temporal artery FDG uptake | Time of diagnosis | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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positron emissions tomography, diagnostic accuracy, case-control