Use of Gallium-68 HA-DOTATATE PET/CT in Giant Cell Arteritis (GCA)

Study Overview
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Brief Summary
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The aim of this study is to compare the use of FDG PET/CT to Ga-68 HA-DOTATATE (abbreviated DOTATATE) PET/CT in patients with active giant cell arteritis (GCA) started on prednisone to understand if DOTATATE can identify more areas of active blood vessel inflammation than FDG.

Detailed Description
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The aim of this study is to prospectively evaluate the potential use of 68-Ga HA-DOTATATE PET/CT for detecting medium-large vessel inflammation in a small number of GCA patients with active disease, as compared to FDG PET/CT, and to understand if DOTATATE uptake correlates with disease activity. Fifteen patients with active GCA (either newly-diagnosed or recently relapsed disease) who are receiving glucocorticoids will be enrolled. Participants will undergo baseline FDG PET/CT and baseline DOTATATE PET/CT scan. Tracer uptake will be described in 8 major vascular territories. DOTATATE PET/CT will be repeated again in 6 months, and tracer uptake will be correlated to clinical disease activity, and medication use.

Official Title
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Evaluating the Use of Gallium-68 HA-DOTATATE Positron Emission Tomography/Computerized Tomography (PET/CT) in Patients With Giant Cell Arteritis (GCA.)

Conditions
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Giant Cell Arteritis

Intervention / Treatment
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* Diagnostic Test: 68-Ga HA-DOTATATE PET/CT


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Participants must: Meet the revised GCA diagnosis criteria (modified from ref 1) Have either newly-diagnosed or relapsing disease Have active disease (modified from ref 1, to remove ESR/CRP requirements) Have been empirically started on glucocorticoid treatment (or had baseline glucocorticoid dose increased, in the case of relapsers) ≤ 2 weeks of enrolment Participant must be have had (or will be willing to undergo) an urgent FDG-PET/CT as part of routine clinical care. GCA diagnosis criteria (modified from ref 1, to remove ESR requirement). Age ≥ 50 years And at least 1 of a. or b. : Unequivocal cranial symptoms of GCA (new headache, scalp or temporal artery tenderness, ischemia-related vision loss, jaw/mouth claudication Unequivocal symptoms of polymyalgia rheumatica (PMR), defined as shoulder and/or hip girdle pain associated with inflammatory stiffness And at least 1 of a. or b.: Temporal artery biopsy revealing features of GCA Evidence of large-vessel vasculitis by angiography or cross-sectional imaging study such as magnetic resonance angiography (MRA), computed tomography angiography (CTA), or positron emission tomography-computed tomography (PET-CT) Exclusion Criteria: Patients not meeting the above criteria or who are unable to provide informed consent will be excluded.

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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Design Details

Primary Purpose: Diagnostic
Intervention Model: Single Group Assignment
Interventional Model Description: 68-Ga HA-DOTATATE PET/CT will be performed in all participants as part of study protocol. Participants will receive an intravenous infusion of 3MBq/kg of 68Ga HA-DOTATATE (to max 200 MBq), followed by CT and PET imaging 60 minutes later. Tracer uptake in each vascular territory will be interpreted qualitatively and quantitatively.
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: DOTATATE<br>All 15 GCA patients will undergo 68-Ga HA-DOTATATE PET/CT imaging at baseline, in addition to FDG PET/CTA (as part of standard of care). DOTATATE PET/CT imaging will be repeated at 6 months follow-up. | Diagnostic Test: 68-Ga HA-DOTATATE PET/CT<br>* See arm description.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Comparison of FDG vs DOTATATE vascular uptake in individual vascular territories using target-blood pool ratios (TBR) |  | time 0 (baseline) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Qualitative comparison of FDG vs DOTATATE vascular uptake in individual vascular (scores 0-3) territories using visual uptake scores |  | time 0 (baseline) | 
| Changes in vascular DOTATATE uptake scores over time (quantitatively and qualitatively) |  | 6 months | 
| Correlation between vascular DOTATATE uptake scores and clinical status |  | 0 and 6 months | 
| Correlation between vascular DOTATATE uptake scores and cumulative glucocorticoid exposure |  | 0 and 6 months |