Evaluation of 68Ga-FAPI-46 and Fluor-18-FDG PET/MRI in Paediatric Sarcoma Patients

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What is this study about?

The trial focuses on children with Paediatric sarcoma, a rare type of cancer that starts in the muscles or other soft tissues. The study uses a new imaging substance called 68Ga-FAPI-46 that is given by an intravenous (into a vein) injection. For comparison, a commonly used substance named Fluor-18-FDG is also injected. Both substances are designed to highlight cancer cells during a scan that combines two imaging techniques, called PET/MRI, which creates detailed pictures of the whole body.

The purpose of the study is to evaluate whether the new scan can improve the detection and assessment of tumor lesions at the time of first diagnosis, during treatment, and if the disease returns. Participants will receive the injection, then lie on a scanning table while the machine takes images; this will be done at several visits that match the usual points when doctors check the disease. The images are read by doctors to see how well the new substance works compared with the standard one, and the overall experience of the children and their families is also recorded.

1 baseline imaging (primary staging)

after enrollment, you will receive an intravenous injection of 68ga-fapi-46. the dose is calculated as 2.4 megabecquerel for each kilogram of body weight and is given as a quick (bolus) injection.

following the injection, you will lie on a table while a whole-body pet/mri scanner creates detailed pictures of your body. the scan takes about 30 to 60 minutes.

in the same visit, a second tracer called fluor-18-fdg is injected at a dose of 3.6 megabecquerel per kilogram, also as an intravenous bolus. after a short waiting period, another pet/mri scan is performed to provide a standard comparison.

2 treatment monitoring scans

during your regular cancer treatment, you will return for additional imaging sessions. each session repeats the same steps: an intravenous injection of 68ga-fapi-46 (2.4 megabecquerel per kilogram) followed by a whole-body pet/mri scan.

if the study protocol includes it, a second injection of fluor-18-fdg (3.6 megabecquerel per kilogram) may also be given, with a subsequent scan to compare results over time.

3 relapse imaging (if disease returns)

if your doctors determine that the sarcoma has come back, you will undergo another imaging round using the same procedures: injection of 68ga-fapi-46 at 2.4 megabecquerel per kilogram, followed by a whole-body pet/mri scan.

a comparator injection of fluor-18-fdg at 3.6 megabecquerel per kilogram may also be performed, with an additional scan to help assess the new disease activity.

Who Can Join the Study?

Be younger than 18 years old (a child or teenager).
Have been referred to the Department of Paediatric and Adolescent Medicine at Copenhagen University Hospital, Rigshospitalet for evaluation of any type of sarcoma – a cancer that starts in muscle, bone, or other connective tissue.
Be able (or have a parent or legal guardian) to read and understand the study information sheet, called the Participant Information Sheet, in Danish or English, and be able to sign the Informed Consent Form (a document that shows agreement to join the study).

Who Cannot Join the Study?

Pregnancy or lactation – you cannot join if you are pregnant or are breastfeeding a baby.
Inability to stay still for the imaging unless you receive medication to make you sleepy (sedation) – if you need sedation to cooperate, you are excluded.
Severe fear of tight spaces (claustrophobia) or any positive findings on the MRI safety checklist (a list that looks for metal implants or other safety issues) – these prevent participation.
Previous allergic reaction to substances similar to the study drug [68Ga]Ga-FAPI-46 – if you have been allergic to related compounds, you cannot take part.

Where you can join this trial?

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Other Sites

Site Name	City	Country	Status
Rzzyicivluxqah	Copenhagen	Denmark

Trial status

Country	Status	Recruitment Start
Denmark	Not yet recruiting	02.11.2026

Trial locations

Investigated Drugs:

68Ga-FAPI-46 is a special radioactive substance that attaches to a protein called FAP, which is often found on the surface of cancer cells and the surrounding tissue. In this trial it is injected into the bloodstream and then scanned with a combined PET/MRI machine. The scan shows where the tracer has gathered, helping doctors see the size, location, and spread of sarcoma tumors in children at the time of first diagnosis, during treatment, and if the disease comes back.

Fluor-18-FDG is a commonly used radioactive sugar molecule that highlights areas of high metabolism, such as many cancers. It is also given by injection and imaged with PET. In this study it serves as the standard comparison, allowing researchers to see how the new FAPI tracer performs against the traditional glucose‑based imaging method.

Investigated Diseases:

Sarcoma

Pediatric sarcoma – A pediatric sarcoma is a cancer that starts in the connective tissues such as muscle, bone, fat, or cartilage of children and adolescents. It often appears as a firm, painless lump that can grow larger over weeks or months. The tumor may invade nearby structures, causing swelling or functional problems in the affected area. In some cases, cancer cells can spread through the bloodstream to other parts of the body, such as the lungs or other bones. The disease can progress from a localized growth to widespread involvement if not monitored closely.

Trial ID:

2025-524874-41-00

Protocol code:

PsiFI

Trial Phase:

Therapeutic exploratory (Phase II)

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Evaluation of 68Ga-FAPI-46 and Fluor-18-FDG PET/MRI in Paediatric Sarcoma Patients

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Who Can Join the Study?

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