Magnetic seeds guided by an MRI scanner heat and destroy tumors in the brain. The corresponding study was conducted by researchers in University College London, UK, and published in Advanced Science.
A glioblastoma is an aggressive form of cancer that occurs in the brain or spinal cord. Although relatively rare, it is almost always lethal. Surgery is a common treatment option for the condition; however average survival times following procedures range between 12-18 months.
MRI scanners are readily available in hospitals worldwide where they are often used to diagnose illnesses, including cancer. For the present study, the researchers developed a therapy known as ‘minimally invasive image-guided ablation’ (MINIMA). The novel therapy involves a ferromagnetic thermoseed that is navigated to tumors using magnetic propulsion gradients generated by an MRI scanner. The seed is then heated remotely to kill off 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. 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." said Professor Mark Lythgoe, senior author of the study.
Lead author of the study, Rebecca Baker, explained that the novel technique guides metal alloy seeds- which are spherical and 2mm in size- to a precision of 0.3mm, and thus may rule out the need for open surgery. This, she said, could especially benefit patients as it reduces recovery time and minimizes side effects.
To see how MINIMA works in vivo, the researchers tested it on mouse models of brain tumors. The mice were anesthetized before the procedure. The seeds were then superficially implanted into their brain tissue, where they were then guided towards cancer cells using MRI. The seeds were then removed through the original tract using a permanent magnet. Through the procedure, the researchers were able to induce localized, and controlled cell death to target tissues.
The researchers say that the new technique may also be adapted to treat other kinds of cancers, such as prostate cancer, which affects one in eight men. While treatments such as radiotherapy and surgery are often effective, they can lead to undesirable side effects such as incontinence and impotence. The extra precision that comes with MINIMA could sidestep these side effects and offer those with cancer a less invasive treatment option.
"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," added Professor Lythgoe.