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A Study Using [AL[18F]F]FAPI-74 PET Scan to Improve Diagnosis and Monitoring of Giant Cell Arteritis in Patients with This Blood Vessel Disease

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What is this trial about?

A plain-language summary of the goals, design and what participants do

This study involves people who may have Giant Cell Arteritis, which is a condition where certain blood vessels, especially those in the head and neck area, become inflamed and swollen. This inflammation can cause problems such as headaches, jaw pain, and in some cases, vision loss. The study will use a substance called [18F]FAPI-74, which is given as an injection into a vein. This substance helps make images of areas in the body where certain cells called fibroblasts are very active. Fibroblasts are cells that can contribute to inflammation and scarring in blood vessels. The substance will be used during special imaging scans to see if it can help doctors better understand what is happening in the blood vessels of people with this condition.

The purpose of this study is to find out if using [18F]FAPI-74 with advanced scanning technology can help doctors see active inflammation in small blood vessels, such as those that supply blood to the eyes, and to compare how well this new method works compared to the current standard imaging method that uses a different substance called FDG. The study also wants to see if this new imaging method can identify long-lasting changes in the blood vessels caused by ongoing activity of fibroblast cells. Additionally, the researchers will examine tissue samples from blood vessels to better understand how these cells play a role in the disease.

People taking part in this study will receive two different types of scans using different imaging substances. One scan will use the new substance [18F]FAPI-74 and the other will use FDG, which is the substance currently used in regular practice. These scans will be done using a type of imaging technology called PET, which stands for positron emission tomography, and this creates detailed pictures of the inside of the body. The scans will help doctors see where inflammation is present in the blood vessels. If treatment with steroid medications needs to be started urgently because of serious symptoms like vision problems, both scans will be done within the first three days after starting treatment. The study will follow participants to see how the inflammation changes over time and whether it goes away with treatment.

The research process

The trial runs in 5 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Initial consent and screening

    Your legally authorized representative or you will provide written consent before any procedures begin.

    Your age will be confirmed to ensure you are at least 18 years old.

    If you are female, a pregnancy test will be performed to confirm you are not pregnant. You must be past menopause, surgically sterile, or using effective birth control methods.

    Your physician will confirm that you have symptoms suggesting giant cell arteritis, which is an inflammation of blood vessels, particularly those in the head and neck area.

    Ideally, treatment with glucocorticosteroids (anti-inflammatory medications) should not have started yet. However, if you develop urgent symptoms affecting your vision, treatment will begin immediately, and the scans will be performed within the first 3 days of starting this medication.

  2. Step 2

    First imaging scan with FAPI tracer

    You will receive an injection of a radioactive tracer called [Al[18F]F]FAPI-74. This substance is given through a vein as a single injection.

    This tracer is a solution for injection that helps identify areas of inflammation and abnormal tissue activity in your blood vessels.

    After receiving the injection, you will undergo a PET/CT scan, which is an imaging procedure that combines two types of scans to create detailed pictures of your blood vessels and surrounding tissues.

    This scan will focus on detecting active inflammation in your arteries, including the small blood vessels near your eyes called ophthalmic arteries.

    The scan will also identify areas where certain cells called fibroblasts are abnormally active, which may indicate chronic inflammation.

  3. Step 3

    Second imaging scan with FDG tracer

    You will receive a second injection of a different radioactive tracer called FDG, which is the standard tracer currently used for diagnosing giant cell arteritis.

    This injection will also be given through a vein as a single dose.

    You will undergo another PET/CT scan after receiving this tracer.

    This scan serves as a comparison to the first scan to evaluate which tracer provides better diagnostic information.

    Both scans together will help determine the presence and extent of inflammation in your blood vessels.

  4. Step 4

    Follow-up imaging during remission

    At a later time, when your condition is in remission (meaning the inflammation has decreased or resolved with treatment), you will undergo additional imaging scans.

    You will receive injections of both the FAPI and FDG tracers again, similar to the initial procedures.

    These follow-up scans will assess changes in inflammation and fibroblast activity compared to the scans performed at diagnosis.

    The comparison will help evaluate how well the treatment has worked and whether any chronic changes remain in your blood vessels.

  5. Step 5

    Tissue sample analysis (if applicable)

    If a temporal artery biopsy is performed as part of your standard diagnostic workup, a small sample of tissue from the artery near your temple will be collected.

    This tissue will be analyzed using advanced laboratory techniques to study specific cell types, including FAP-positive fibroblasts, which are cells that may play a role in the disease process.

    The results from this analysis will be compared with the findings from your imaging scans to better understand the disease mechanisms.

Who can join the trial?

5 criteria

  • You must be at least 18 years old or older when signing the consent form
  • You must provide written informed consent, which means you agree in writing to take part in the study, or someone legally allowed to make decisions for you must provide this consent, before any tests or procedures begin
  • If you are a woman, you must be past menopause, which means your monthly periods have permanently stopped, or you must have had surgery that prevents pregnancy, or you must be using effective birth control methods and have a negative pregnancy test
  • Your doctor must strongly suspect that you have Giant Cell Arteritis, which is a condition where blood vessels become inflamed, based on your symptoms and their medical experience
  • You must not have started treatment with glucocorticosteroids, which are medications that reduce inflammation in the body. However, if you develop urgent symptoms that affect blood flow to your eyes or other organs, treatment with these medications will be started and the required scans will be done within the first 3 days of starting this treatment

Who cannot join the trial?

3 criteria

  • No specific exclusion criteria (reasons why you cannot participate) have been listed for this clinical trial
  • The study doctor will review your medical history and current health condition to determine if you are suitable to take part in this research
  • General safety considerations will be assessed during the screening process (initial evaluation before joining the study)
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Investigated drugs

  • NX

    is an investigational imaging agent used with PET/CT scanning. It helps doctors see and measure inflammation in blood vessels, particularly in the arteries around the eyes. In this study, it is being tested to see if it can detect active inflammation in patients with giant cell arteritis.

  • FAPI

    is an investigational imaging agent used with PET/CT scanning. It attaches to special cells called fibroblasts that become active during inflammation and scarring in blood vessels. In this study, it is being tested to see if it can identify both active inflammation and long-term scarring in patients with giant cell arteritis, and to compare how well it works compared to the standard imaging agent.

  • FDG

    is a radioactive sugar solution used with PET scanning. It is the current standard imaging agent used to detect inflammation in blood vessels. In this study, it serves as the comparison to see if the newer imaging agents work as well or better.

What is already known about the treatment

  • FAPI

    FAPI is an imaging agent used in PET/CT scans to detect and monitor inflammation in blood vessels, specifically being studied for diagnosing giant cell arteritis. This substance works by attaching to activated fibroblasts, which are cells involved in chronic inflammation and tissue changes in the walls of arteries. FAPI is currently being investigated in clinical trials to determine if it can diagnose arteritis as effectively as the current standard imaging method called FDG PET. The imaging technique helps doctors visualize areas of active disease and assess how well treatment is working by showing where abnormal fibroblast activity is occurring in the body.

  • FDG

    FDG is a radioactive glucose-based tracer used in PET scanning to detect areas of increased metabolic activity in the body, and it is currently the gold standard imaging method for diagnosing giant cell arteritis. This substance works by being absorbed by cells that are using high amounts of energy, such as inflammatory cells in inflamed blood vessel walls. FDG accumulates in areas where there is active inflammation, allowing doctors to see which arteries are affected by the disease. It is widely used in clinical practice for diagnosing and monitoring various inflammatory conditions and cancers.

Investigated diseases

Giant Cell Arteritis – Giant cell arteritis is an inflammatory condition that affects the blood vessels, particularly the arteries in the head and neck region. The disease causes the walls of the arteries to become inflamed and swollen, which can narrow or block blood flow through these vessels. It most commonly affects the temporal arteries, which are located on the sides of the head near the temples. The inflammation can spread to involve other arteries, including the ophthalmic artery that supplies blood to the eyes. As the disease progresses, the reduced blood flow can affect various tissues and organs that depend on these arteries. The condition typically develops gradually, with symptoms that may worsen over time if the inflammation continues.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IVTrial ID2025-523880-39-02Estimated enrolment60 patientsSponsorUZ Leuven

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