A new type of scan measuring whether tissues are ‘stiff’ or elastic can be used to image tumours and assess whether they are responding to treatment.
Scientists at The Institute of Cancer Research, London, found that the imaging technique – called magnetic resonance elastography - could rapidly detect whether cancer cells were being killed by drug treatment.
The study, published this week in the British Journal of Cancer, was designed to exploit the fact that malignant tumours tend to be stiffer, or less elastic, than healthy tissue.
It was funded by a Dorothy Hodgkin Postgraduate Award from the EPSRC, AstraZeneca and Cancer Research UK, with additional support from the NIHR Biomedical Research Centre at The Royal Marsden NHS Foundation Trust and The Institute of Cancer Research (ICR), and the Wellcome Trust.
ICR scientists treated four mice with human colorectal cancer with the drug ZD6126, which kills tumours by disrupting their blood flow, and used magnetic resonance elastography to measure tumour stiffness before and after treatment. Tumours become less stiff when cells begin to die, so measuring tissue stiffness could show when cancer is responding to treatment.
They found that after drug treatment, elastography showed a marked decrease in tumour stiffness, which dropped by an average of 30% after 24 hours, while six mice given a placebo saw no change in tumour stiffness. Follow-up tests showed that ZD6126 destroyed the core of their tumours, confirming that changes in tumour stiffness were linked to cell death.
The researchers also used diffusion-weighted magnetic resonance imaging to calculate the apparent diffusion coefficient (ADC) – a more established way of monitoring tumour cell death – but found that ADC values did not change significantly after 24 hours of treatment with ZD6126.
This suggests not only that magnetic resonance elastography can be used to monitor cell death in tumours, but that it could be more sensitive to early cell death from cancer treatments than current methods.
Dr Simon Robinson, Team Leader in Radiotherapy & Imaging at The Institute of Cancer Research, London, said: “Magnetic resonance elastography is an emerging technology to non-invasively image tumour stiffness, which is showing a lot of promise for cancer diagnosis. This study shows that elastography can quantify changes in tissue stiffness, and that these could be used to measure cancer cell death following treatment.”
“Other imaging methods can monitor cell death in tumours, but we found that magnetic resonance elastography was more sensitive. In the future, it could help doctors monitor more accurately whether a patient’s cancer has relapsed or the likelihood of it spreading to other parts of the body, in addition to how well treatments are working.”