MRI-guided prostate biopsy is not available anywhere else in the region
Last summer, WellSpan Imaging Services began offering MRI-guided prostate biopsy, an important new tool for detecting prostate cancer. Presently, it is available nowhere else in south central Pennsylvania.
“Very few sites on the East Coast are currently doing MRI-guided prostate biopsy,” said Joanne Trapeni, D.O., division chief for women's and interventional imaging, “It’s a bit more common on the West Coast.”
Trapeni began investigating the technology two years ago, finding it added a new level of precision to the often murky world of prostate-cancer detection.
Prostate cancer is the most frequently diagnosed form of noncutaneous cancer in men, and the second leading cause of cancer death in men. Its elusiveness stems from an unusually slow growth process that is typically symptom-free, although it does become aggressive in one-third of cases.
Trapeni notes that MRI-guided biopsy is intended for men with the potential warning signs of prostate cancer—namely an abnormal prostate or an elevated prostate-specific antigen (PSA) level—but whose trans-rectal ultrasound (TRUS) guided biopsy is negative.
TRUS biopsies are common; more than a million are performed in the United States every year. With TRUS, an ultrasound probe with a biopsy instrument is passed into the rectum to obtain a dozen core tissue samples from the prostate.
“TRUS is a good first line of defense because it’s inexpensive and can be done in the urologist’s office,” Trapeni said. “The problem is that on ultrasound a lot of cancers can match the surrounding tissue and not be readily delineated.”
In as many as 62 percent of cases, ultrasound fails to identify a prostate cancer requiring treatment. This likelihood of a false-negative causes many men to undergo multiple TRUS procedures, typically at six-month intervals.
MRI can hone in on suspicious nodules
With MRI-guided biopsy, however, the likelihood of a false-negative drops to just 20 percent. The difference comes from the precision of MRI, which can hone in on suspicious nodules as small as five or six millimeters in diameter.
“If an MRI-guided biopsy is negative, the patient’s confidence level can be that much higher,” said Trapeni. “It is a directed, localized biopsy of the abnormality.”
She added that TRUS focuses only on the prostate, while MRI also offers views of the bladder, lymph nodes and bones.
An MRI-guided biopsy requires two outpatient visits, each lasting less than an hour. The first is for a diagnostic study to identify lesions to target during the biopsy. A few days later, the patient returns for the procedure itself.
“We have a very sophisticated computer program that overlays a blood map, lining up everything in the diagnostic study with the new study,” Trapeni explains.
Unlike TRUS, which requires the insertion of an ultrasound probe, MRI-guided biopsy uses only a small diameter biopsy device. And instead of taking a dozen tissue samples, it needs only two.
These differences can mean less discomfort and bleeding. The studies are performed in a closed MRI unit.
Preparation and potential risks are the same as for TRUS biopsy. The patient will be prescribed antibiotics to reduce the chance of infection, and will require an enema one to two hours before the procedure. Lidocaine gel is used for needle-guide insertion.
Prior to leaving the facility the patient will be asked to void, ensuring that urinary retention is not a problem. Trace amounts of blood in the urine and semen are common for a few days afterward.
Approximately one in six men will be diagnosed with prostate cancer during his lifetime. Early detection is essential to effective treatment. MRI-guided biopsy can help eliminate the doubt left behind by a negative TRUS biopsy.