Study of 18F-AlF-FAPI-74 PET/CT imaging compared to standard 18F-FDG PET/CT in patients with fever of unknown origin, IgG4-related disease, and axial spondyloarthritis

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What is this study about?

This study focuses on evaluating a new imaging method for several inflammatory conditions including Fever of Unknown Origin, IgG4-related Disease, and Axial Spondyloarthritis. The study compares two different imaging tracers: a new substance called [18F]AlF-FAPI-74 and the standard tracer [18F]FDG, both used in combination with PET/CT scanning. PET/CT is an advanced imaging technique that combines two types of scans to create detailed pictures of the body.

The purpose of this research is to determine if the new imaging tracer can work as well as or better than the current standard method in detecting and evaluating inflammatory conditions. The study will look at how well each tracer can identify the source of unexplained fever and inflammation, assess the extent of IgG4-related disease (a condition that can affect multiple organs), and distinguish between inflammatory and mechanical back pain in patients with spine problems.

During the study, participants will receive an intravenous injection of the imaging tracer before undergoing the PET/CT scan. Some participants may need to have two scans, particularly those with spine conditions who will be evaluated before and after three months of treatment. The maximum amount of tracer used for each scan will be 100 MBq, with a total maximum dose of 550 MBq over the entire study period.

1 Initial medical imaging examination

You will undergo a PET/CT scan (a special type of medical imaging that combines two scanning techniques)

The scan will be performed using a standard imaging substance called [18F]FDG

This initial scan must be completed within 4 weeks before the next step, preferably within 2 weeks

2 Study medication administration

You will receive an intravenous injection (through a vein) of the study medication called [Al[18F]F]FAPI-74

The medication will be given as a solution for injection

This is a new type of imaging substance that targets specific cells involved in inflammation

3 Second medical imaging examination

After receiving the study medication, you will undergo another PET/CT scan

This scan will help evaluate how the new imaging substance works in your condition

4 Additional scan for specific conditions

If you have been diagnosed with axial spondyloarthritis (a type of inflammatory spine condition), you will have an additional scan after 3 months of treatment

This follow-up scan will help assess how well your treatment is working

Who Can Join the Study?

Must be at least 18 years old, both men and women can participate
Must provide written informed consent before any screening procedures
For patients with fever of unknown origin (FUO):
- Must have illness lasting more than 3 weeks
- Temperature must exceed 38.3°C on more than 3 occasions
- Diagnosis remains unclear after initial medical tests
- Must have had or plan to have a special imaging test (PET/CT scan) within 4 weeks
For patients with inflammation of unknown origin (IUO):
- Must have illness lasting more than 3 weeks
- Must have elevated inflammation markers in blood tests on more than 3 occasions
- Diagnosis remains unclear after initial medical tests
For patients with IgG4-related disease:
- Must have high clinical suspicion of the condition by an internal medicine specialist
- Must have had or plan to have a special imaging test within 2 weeks
- Must have moderate to high disease activity if previously diagnosed
For patients with back pain:
- Must have inflammatory back pain lasting more than 3 months
- Pain must worsen at night and improve with exercise
- Must have tried two different anti-inflammatory medications for 2-4 weeks without success
For women participants:
- Must be either post-menopausal, surgically unable to become pregnant, or using effective birth control with a negative pregnancy test

Who Cannot Join the Study?

Age under 18 years old
Pregnant or breastfeeding women
Known allergy to any of the study medications or contrast agents
Unable to lie still for the duration of the PET/CT scan (approximately 30 minutes)
Severe claustrophobia that would prevent completion of the imaging procedures
Weight exceeding the scanner table limit (usually 350-500 pounds, depending on equipment)
Previous participation in another clinical trial within the past 30 days
Inability to provide informed consent
Serious medical conditions that could interfere with study participation
History of recent major surgery (within 6 weeks)
Active infection requiring immediate treatment
Impaired kidney function that would affect contrast agent clearance

Note: PET/CT scan is a medical imaging technique that combines two types of scans – Positron Emission Tomography (PET) and Computed Tomography (CT) – to create detailed pictures of the inside of your body.

Where you can join this trial?

Verified and Recommended Sites

No sites found in this category

Verified Sites

Site Name	City	Country	Status
Katholieke Universiteit te Leuven	Leuven	Belgium

Other Sites

No sites found in this category

Trial status

Country	Status	Recruitment Start
Belgium	Recruiting	01.06.2025

Trial locations

Investigated drugs:

[Al[18F]F]Fapi-74

[18F]AlF-FAPI-74 is a novel imaging tracer used in PET/CT scans. It specifically targets fibroblasts (cells that help in tissue repair and are active during inflammation). This tracer helps doctors see areas of inflammation in the body more clearly during scanning procedures.

[18F]FDG (fluorodeoxyglucose) is a standard imaging tracer commonly used in PET/CT scans. It works by targeting cells that use a lot of glucose (sugar), including both cancer cells and inflammatory cells. This is currently the standard method used for detecting areas of inflammation and infection in the body.

Both tracers are radioactive substances that are injected into the body before a PET/CT scan. They are not treatments but rather diagnostic tools that help doctors see what is happening inside the body, particularly in cases of inflammation and inflammatory diseases.

Investigated diseases:

Fever of Unknown Origin – A condition where a person experiences prolonged fever without a clear cause despite initial medical evaluation. The fever typically lasts for several weeks, with body temperature repeatedly rising above normal levels. The underlying cause can be related to various factors but remains unidentified during initial examinations.

IgG4-Related Disease – A chronic inflammatory condition that can affect multiple organs in the body. It occurs when specific immune cells cause inflammation and fibrosis in various tissues. The condition typically develops gradually and can involve several organs including the pancreas, salivary glands, and lymph nodes.

Axial Spondyloarthritis – A chronic inflammatory arthritis that primarily affects the spine and sacroiliac joints connecting the spine to the pelvis. The condition typically begins with back pain and stiffness, especially in the morning or after periods of inactivity. The inflammation can lead to gradual fusion of vertebrae over time, primarily affecting young adults.

Inflammatory Back Pain – A type of back pain characterized by inflammation in the joints and tissues of the spine. The pain typically improves with exercise and worsens with rest, particularly notable in the morning. The discomfort usually develops gradually over time and affects primarily the lower back and buttocks.

Trial ID:

2024-516464-28-00

Trial Phase:

Therapeutic use (Phase IV)

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