A Prospective Dose-Escalation Study to Define an Ablative Dose of Yttrium-90 Transarterial Radioembolization Using Advanced Dosimetry and Functional MRI (MARGIN Study)

Currently, doctors use Yttrium-90 (Y90) radiation segmentectomy, a treatment that delivers tiny radioactive beads into the blood vessels feeding the liver tumor. These beads give off radiation that helps kill the cancer cells from the inside, right where the tumor is located. This approach allows doctors to target the tumor very precisely, while keeping the rest of the liver as healthy as possible. However, the exact dose needed to fully ablate a tumor without damaging healthy liver tissue is not well established.

To answer this, the study team will use specialized imaging before and after treatment to evaluate how the radiation is distributed in the liver and how the liver responds over time. These imaging procedures include PET/CT or PET/MRI scans, which are standard medical imaging tests that are not considered experimental. During these scans, a small amount of a safe radioactive substance is injected into a participant's vein. This helps show where the Y90 beads are located in the participant's liver.

In a PET/CT scan, two types of imaging are performed during the same session. The PET scan detects signals from the radioactive substance and shows how the participant's liver is functioning at a molecular level. The CT scan, which uses x-rays to create detailed cross-sectional images of the body, provides a precise anatomical map that helps localize these functional signals. Together, they give a clear picture of both the structure and activity within the liver.

PET/MRI works similarly but uses magnetic fields and radio waves instead of x-rays. It combines the functional information from the PET scan with the highly detailed soft-tissue images from MRI, which can be especially useful in evaluating the liver. Both imaging techniques are done during a single visit, with the PET component typically performed at the same time as the CT or MRI, depending on which machine is used. Participants will also undergo a liver MRI with dual contrast using Eovist and extracellular gadolinium, another standard imaging procedure. MRI uses magnets and radio waves to take detailed pictures of the liver. Eovist is a special dye injected into a participant's vein during the scan that helps highlight liver tissue and shows how well different parts of the liver are functioning. Extracellular gadolinium is a more general contrast agent that enhances blood vessels and tissues, providing complementary information. This imaging helps the doctors confirm whether the tumor area was completely treated.

The goal is to determine the safest and most effective dose of radiation to fully treat cancer while preserving healthy liver tissue. This information may help doctors treat future patients more precisely and safely.