MRI-guided biopsy for brain cancer improves diagnosis
6 May 2014
Neurosurgeons at UC San Diego Heath System have combined
real-time MRI technology with non-invasive cellular mapping
techniques to develop a new biopsy method that increases the
accuracy of brain cancer diagnosis.
“There are many different types of brain cancer. Making an
accurate diagnosis is paramount because the diagnosis dictates the
subsequent course of treatment,” said Clark C. Chen, MD, PhD,
vice-chairman of research, division of neurosurgery, UC San Diego
School of Medicine. “For instance, the treatment of glioblastoma is
fundamentally different than the treatment for oligodendroglioma,
another type of brain tumour.”
Chen said that as many as one third of brain tumour biopsies
performed in the traditional manner can result in misdiagnosis. He
cited two challenges with conventional biopsy.
"First, because distinct areas of brain tumours exhibit different
cell densities and higher cell densities are generally associated
with higher tumour grade, biopsies taken from one region may yield a
different diagnosis than if another area is biopsied,” said Chen.
“Second, because tumours are hidden within the brain, surgeons must
use mathematical algorithms to target where the biopsy should occur.
As with all calculations, the process is subject to errors that the
surgeon cannot easily correct in real time once the biopsy has
Chen’s team applied an MRI technique called Restriction Spectrum
Imaging (RSI) to visualize the parts of the brain tumour that
contain different cell densities.
“RSI allows us to identify the regions of the cell that are most
representative of the entire tumour,” said Chen. “By targeting
biopsies to these areas, we minimize the number of biopsies needed
but still achieve a sampling that best characterizes the entire
To ensure a targeted biopsy, Chen performs the procedure in the
MRI suite while the patient is under general anaesthesia. Because
conventional biopsy equipment cannot be used in the MRI, Chen uses a
special MRI-compatible system called ClearPoint. This system
utilizes an integrated set of hardware, software, and surgical
equipment to allow the surgeon to target and visualize the path of
the biopsy as well as the actual biopsy site, intraoperatively.
“Surgeons have been performing brain biopsies in a near blind
manner for the past fifty years. The ability to see where the biopsy
needle is located and where the biopsy is being performed in real
time is groundbreaking,” said Chen. “This combination of
technologies gives me an opportunity to immediately adjust my
surgical approach while minimizing risk.”