A PUBLICATION OF THE PATRICK C. WALSH PROSTATE CANCER RESEARCH FUND

Robot Uses MRI to Target the Prostate


The MrBot works in conjunction with an MRI scanner,
and is remotely controlled. "It represents a major
technological breakthrough," says its inventor, Dan Stoianovici,
"because no other instrument could precisely, safely, and remotely
operate in the high magnetic field of the MRI without interfering
with the image." Early tests have shown promising results,
and the robot is nearing clinical trials.

 

Meet the MrBot. It’s a robot (not pronounced, as you might think, “Mr. Bot”) designed for making needle biopsies or implanting radiation seeds in the prostate, and it’s done using MRI, not ultrasound. “Needle access of the prostate is routinely performed under ultrasound guidance,” explains scientist Dan Stoianovici, Ph.D., the R. Christian B. Evensen Scholar, “because the ultrasound is widely accessible and economical. But it fails to show exact spots of prostate cancer, and it can’t tell us the extent of the disease.”

Because the doctor’s ability to see what’s happening is not terribly good, Stoianovici says, “prostate biopsies are performed blindly but systematically. Too often, however, biopsy results are false negatives” — and this, he adds, is most likely because the needles miss the spots of tumor, which in the prostate are notoriously hard to predict. “Biopsies are taken from the most probable locations of the gland, where cancer is known to reside according to statistics.” But a needle is not stuck in a particular part of tissue because the urologist sees something suspicious there. “Simply speaking, your biopsy is taken based on someone else’s data, and the needle is placed where a cancer is most likely to be.”

The same image-guiding problem also affects brachytherapy and thermal therapies. “Misplaced probes create recurrence or side effects,” he says. “If biopsies could be more precisely guided, based on cancer imaging” — what can actually be seen — “not only could this increase early detection rates, but it could provide a way of correlating cancer images with pathology for generating a working map of the disease.” The MrBot is specifically designed for the prostate. By changing the needle drivers, the robot can be used for different purposes — biopsy, brachytherapy, cryotherapy, or therapeutic injections. Stoianovici is preparing the robot for clinical trials, and he is excited about the possibilities — not only of improving biopsies, but of targeting treatment exactly where the tumor is known, not just suspected, to be.

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