MRI-Guided Magnetic Seeds Heat and Destroy Tumors

Scientists at University College London have developed a highly targeted anti-tumor treatment. The approach involves guiding ferromagnetic thermoseeds to the site of a tumor using the magnetic fields generated by an MRI scanner. The magnetic seeds can then destroy the tumor through localized heating that is induced by an MR-compatible thermoablative device. The technique is called “minimally invasive image-guided ablation” or MINIMA, and the researchers hope that it could provide an effective treatment option in brain and prostate cancers.

Targeting cancer is a tricky business, but these researchers have developed a technique that converts an MRI scanner from a diagnostic device to a therapeutic one that can help to guide a thermoablative treatment directly to the site of a tumor. The MINIMA technique involves implanting 2 mm-sized metal alloy beads (the magnetic seeds) superficially and then using the magnetic fields of an MRI scanner to guide them to the tumor site. Once present at the tumor, the beads can be remotely activated to produce heat, killing nearby cancer cells.

“MINIMA is a new MRI-guided therapy that has the potential to avoid traditional side effects by precisely treating the tumor without harming healthy tissues,” said Mark Lythgoe, one of the developers of the new technique. “Because the heating seed is magnetic, the magnetic fields in the MRI scanner can be used to remotely steer the seed through tissue to the tumor. Once at the tumor, the seed can then be heated, destroying the cancer cells, while causing limited damage to surrounding healthy tissues.”

A major benefit of the approach is the ability to image the tumor and magnetic seeds while performing the magnetic guidance and thermoablation, limiting the potential for off-target effects. “Using an MRI scanner to deliver a therapy in this way allows the therapeutic seed and the tumor to be imaged throughout the procedure, ensuring the treatment is delivered with precision and without having to perform open surgery,” said Rebecca Baker, another researcher involved in the study. “This could be beneficial to patients by reducing recovery times and minimizing the chance of side effects.”

The University College London team tested the system in a mouse tumor model, and, impressively, were able to eradicate their tumors entirely. The concept of navigating small objects about the body has other application besides destroying tumors. “In the longer term, we will change the shape of the seed to act as a tiny cutting scalpel that could be guided through tissue, which would allow surgeons to perform remotely controlled operations, revolutionizing non-invasive surgery,” said Lythgoe.

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