MRI-Ultrasound Fusion-Guided Biopsy Detects Prostate Cancer

But the tumor now can be detectable by direct sampling of tumor spots detected using magnetic resonance imaging (MRI), in combination with real-time ultrasound, according to the University of California, Los Angeles (UCLA; USA) researchers.

The study’s findings are published December 10, 2012, in the early online edition of the Journal of Urology and are scheduled for print publication in the journal's January 2013 issue. The UCLA study indicates that the MRI–ultrasound fusion biopsy, which is much more accurate than a conventional blind biopsy, may lead to a decrease in the number of prostate biopsies performed and could allow for the early detection of serious prostate tumors.

The study involved 171 men who were either undergoing active surveillance to monitor slow-growing prostate cancers or who, despite prior negative biopsies, had persistently elevated levels of prostate-specific antigen (PSA), a protein produced by the prostate that can indicate the presence of cancer. The UCLA biopsies using the new technique were done in about 20 minutes in an outpatient clinic environment under local anesthesia.

Yearly, almost all of the one million prostate biopsies performed in the United States are prompted by elevations in prostate-specific antigen (PSA) levels, and approximately 240,000 new instances of prostate cancer are found each year. Therefore, approximately 75% of biopsies are negative for cancer. However, many men with negative biopsies but elevated PSA levels may still harbor malignant tumors—tumors missed by traditional biopsies, according to the study’s senior author, Dr. Leonard S. Marks, a professor of urology and director of UCLA’s active surveillance program.

“Early prostate cancer is difficult to image because of the limited contrast between normal and malignant tissues within the prostate,” Dr. Marks said. “Conventional biopsies are basically performed blindly because we can’t see what we’re aiming for. Now, with this new method, which fuses MRI and ultrasound, we have the potential to see the prostate cancer and aim for it in a much more refined and rational manner.”

The new targeting process is the outcome of four years of work funded by the US National Cancer Institute and based at the Clark Urology Center at UCLA.

Since the mid-1980s, prostate cancer has been diagnosed using transrectal ultrasound to sample the prostate. Unlike most other cancers, prostate cancer is the only major malignancy diagnosed without actually visualizing the tumor as a biopsy is performed, according to Dr. Marks.

With the development of sophisticated MRI technology, the ability to image the prostate improved and provided an image of tumors within the organ. However, trying to biopsy the prostate with the patient inside an MRI scanner turned out to be costly, awkward, and time-consuming. However, with the development of the new MRI-ultrasound fusion process, the biopsy can now be performed in a clinic setting.

In the study, the volunteers first underwent MRI to visualize the prostate and any lesions. That data were then fed into a device called the Artemis, which electronically fuses the MR images with real-time, three-dimensional (3D) ultrasound, 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 the biopsy,” Dr. 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 detected in 53% of 171 study participants. Of those tumors found using the fusion biopsy technique, 38% had a Gleason score of greater than seven, indicating an aggressive tumor and one more likely to metastasize than a tumor with lower scores. Once prostate cancer spreads, it is much more complicated to treat, and survival drops.

The UCLA study group of investigators included physicians and scientists from urology, radiology, pathology, the Center for Advanced Surgical and Interventional Technology (CASIT) and biomedical engineering. “Prostate lesions identified on MRI can be accurately targeted with MR-Ultrasound fusion biopsy in a clinic setting using local anesthesia,” the study authors stated. “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.”

The Artemis technology was developed by Eigen Corp. (Grass Valley, CA, USA).

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