MRI-ultrasound fusion provides a better visual for obtaining prostate biopsy
Ground-breaking research demonstrates that prostate cancer can be diagnosed using image-guided biopsy. These findings may end a 25-year era of blind biopsy.
Traditionally, prostate cancer has been found only by blind biopsy using transrectal ultrasound to sample the prostate, which is a procedure that dates back to the 1980s. Unlike most tumors, prostate cancer is the only major malignancy diagnosed without actually visualizing the tumor as the biopsy is obtained.
Elevations in serum prostate-specific antigen (PSA) level trigger nearly all of the one million prostate biopsies obtained in the United States every year. Annually, approximately 240,000 new cases of prostate cancer are discovered. Thus, approximately 75% of biopsies are negative for cancer. However, many men with elevated PSA levels whose biopsy results are negative may still harbor malignant tumors that were missed by conventional biopsy methods.
“Early prostate cancer is difficult to image because of the limited contrast between normal and malignant tissues within the prostate,” said Leonard S. Marks, of UCLA. “Conventional biopsies are basically performed blindly, because we can't see what we're aiming for.” This new method fuses magnetic resonance imaging (MRI) and ultrasonography, which gives us the potential to see the prostate cancer and aim for it in a much more refined and rational manner, Marks explained.
With the advent of sophisticated MRI, imaging the prostate improved and provided a picture of tumors within the organ. However, trying to biopsy the prostate with the patient inside the MRI scanner has proved to be cumbersome, expensive, and time consuming. Thus the fusion process evolved, permitting the targeted biopsy to be obtained in a clinic setting.
In this study, the volunteers underwent MRI first to visualize the prostate and any lesions. That information was then fed into a device called the Artemis, which fuses the MRI images with real-time, three-dimensional ultrasonography, allowing the urologist to see the lesion during the biopsy.
“With the Artemis, we have a virtual map of the suspicious areas placed directly onto the ultrasound image during biopsy,” Marks said. “When you can see a lesion, you've got a major advantage of knowing what's really going on in the prostate. The results have been very dramatic, and the rate of cancer detection in these targeted biopsies is very high. We're finding a lot of tumors that hadn't been found before using conventional biopsies.”
Prostate cancer was found in 53% of 171 study volunteers. Of those tumors found by the fusion biopsy technique, 38% had a Gleason score greater than 7, which indicates an aggressive tumor and is more likely to spread than tumors with lower scores. Once prostate cancer spreads, it's much more difficult to treat and survival decreases.
“Prostate lesions identified on MRI can be accurately targeted with MRI-ultrasound fusion biopsy in a clinic setting using local anesthesia,” the study states. “Biopsy findings correlate with the level of suspicion on MRI. Targeted prostate biopsy has the potential to improve the diagnosis of prostate cancer and may aid in the selection of patients for active surveillance and focal therapy.”
This research was published in The Journal of Urology (2013; 189(1):86-92).