|SPEAKING OF BETTER PROSTATE BIOPSIES: |
During your basic prostate biopsy a physician, guided by
transrectal ultrasound, uses a needle to take core samples
of tissue throughout the prostate.
"Although several biopsy templates have been proposed,
it is unknown how accurately biopsy samples are obtained
by a physician," says Brady urologist Misop Han, M.D.
In a recent study using a biopsy simulation system, Han
and scientist Dan Stoianovici, Ph.D., compared humans
and robots. Specifically, they asked, who's better at
performing an accurate and reliable biopsy:
Experienced urologists or a newly developed robot?
This study will be published in the Journal of Urology. "
We found that urologists did worse biopsies compared to
the robot," says Han.
"The biopsied samples obtained by urologists were often
clustered and missed some portions of the prostate.
Meanwhile, the robot closely followed the assigned
biopsy template. Most importantly, we found that the
robot most likely will detect more prostate cancer
than experienced urologists." Han believes that robotic
assistance, along with a better biopsy template, has the
potential to improve the accuracy and reliability of prostate
biopsy in the future. The scientists plan to perform a clinical
study to test and confirm their theory.
Nobody loves prostate biopsies – certainly not the men getting them, but the doctors who perform them know that despite their best efforts to sample the entire prostate, they may miss cancer.
More than 1.2 million prostate biopsies are performed each year in the U.S. using transrectal ultrasound as the guidance system. The problem is that "standard grayscale ultrasound imaging provides minimal cancer-specific information in regard to localizing tumors," says Dan Stoianovici, Ph.D., Director of the Urology Robotics Laboratory and The Virginia and Warren Schwerin Scholar. The urologist performs the biopsy according to a template and hopes that by sampling bits of tissue throughout the prostate, if cancer is present it will be detected. "Standard biopsies typically have low sensitivity and low negative predictive value." In other words, if the biopsy does not show cancer, this doesn't necessarily mean that it isn't there. The biopsy could have just missed the mark. Or, it may find small lesions that are unlikely to cause problems. "These uncertainties may contribute to disease overtreatment," Stoianovici continues.
Another imaging technology, MRI of the prostate, provides better pictures but is hard to use as a means of guiding a needle. Stoianovici and colleagues are working to develop technologies for biopsies that target suspicious lesions depicted in MRI. The Urology Robotics Laboratory has developed a new MRI-Safe robot for transrectal prostate biopsy – done in the MRI scanner itself. "The robot presents three degrees of freedom," says Stoianovici, "two for orienting a needle-guide and one for adjusting the depth of needle insertion." Animal tests conducted at the Memorial Sloan-Kettering Cancer Center have shown the feasibility and accuracy of the approach. This research, supported by a grant from the Prostate Cancer Research Program of the Department of Defense, was presented at the American Urological Association's annual meeting in 2012 and won an Outstanding Paper Award from the Engineering and Urology Society.