MRI tracking of tumour ablation by carbon nanotubes

26 July 2010

A new way of monitoring carbon nanotubes as they destroy tumour cells by laser induced heating has been developed by researchers from Wake Forest University Baptist Medical Center in the US.

The work builds on an experimental technique for treating cancer called laser-induced thermal therapy (LITT), which uses energy from lasers to heat and destroy tumours.

Multi-walled carbon nanotubes (MWCNTs) can absorb the energy of a laser and convert it into heat. If the nanoparticles are within a tumour the heat will kill the cancerous cells.

The problem with LITT, however, is that while a tumour may be clearly visible in a medical scan, the particles are not. They cannot be tracked once injected, which could put a patient in danger if the nanoparticles were zapped away from the tumour because the aberrant heating could destroy healthy tissue.

Now the team from Wake Forest Baptist has shown for the first time that it is possible to make the particles visible in the MRI scanner to allow imaging and heating at the same time. By loading the MWCNT particles with iron, they become visible in an MRI scanner. Using tissue containing mouse tumours, they showed that these iron-containing MWCNT particles could destroy the tumours when hit with a laser.

The research was presented at the 52nd Annual Meeting of the American Association of Physicists in Medicine (AAPM) in Philadelphia this month.

"To find the exact location of the nanoparticle in the human body is very important to the treatment," says researcher Xuanfeng Ding MS. "It is really exciting to watch the tumour labelled with the nanotubes begin to shrink after the treatment."

The results are part of Ding's ongoing Ph.D. thesis work -- a multi-disciplinary project led by Suzy Torti, Ph.D., professor of biochemistry at Wake Forest Baptist, and David Carroll, Ph.D., director of the Wake Forest University Center for Nanotechnology and Molecular Materials, that also includes the WFB Departments of Physics, Radiation Oncology, Cancer Biology, and Biochemistry.

A previous study by the same group showed that laser-induced thermal therapy using a closely-related nanoparticle increased the long-term survival of mice with tumours. The next step in this project is to see if the iron-loaded nanoparticles can do the same thing.

If the work proves successful, it may one day help people with cancer, though the technology would have to prove safe and effective in clinical trials.