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Physicians Update

 
Fall 2012: Men's Health

New Imaging Techniques Improve Prostate-Tumor Biopsies

MR images to creates virtual map of suspious area for prostate tumorEach year, approximately 1-million prostate biopsies are performed in the United States. The vast majority of them are prompted by elevated prostate-specific antigen (PSA) levels. Three-fourths of these biopsies are negative, but a proportion of the roughly 750,000 men each year with abnormal PSA and a negative biopsy have a tumor that escapes detection by conventional biopsy.

With a $1.7-million National Cancer Institute grant, a multidisciplinary UCLA team is using new technology to produce targeted biopsies that are proving to be much more accurate than the conventional blind biopsies. The targeted biopsy employs MRI to visualize the prostate tumor, then fuses the MR images with real-time ultrasound using a device called the Artemis, enabling the urologist to see the lesion in real time when performing the biopsy. In addition to being used for diagnosis, this technique is also proving to be an important tool for active surveillance of nonaggressive tumors. UCLA urologist Leonard S. Marks, M.D., heads a group that also includes experts from radiology, pathology and biomedical engineering.

How is the targeted biopsy an improvement over the conventional technique?
Since the mid-1980s, prostate cancer has been diagnosed by using transrectal ultrasound to systematically sample the prostate. Although it's systematic, this is a blind approach. Prostate cancer is the only major cancer diagnosed without visualization of the lesion as a biopsy is performed. The new method employs direct aiming at a lesion during the procedure. We're seeing men every day in our clinic who are referred to us after having negative biopsies and persistently elevated PSA. We perform a multiparametric MRI, and if there is a lesion outside the normal catchment area of conventional biopsy, we can target that. If it turns out to be cancer, we've done a major service by diagnosing it while it's still treatable.

What made this possible?
Early prostate cancer was always difficult to image because of the limited contrast between normal and malignant tissues within the prostate, but that began to change with the advent of sophisticated MRI. However, direct prostate biopsy within the MRI tube has proven cumbersome, expensive, and time-consuming. With the Artemis device, we
can feed in the MR images and have a virtual map of the suspicious areas placed on the ultrasound image during the biopsy, allowing us to target the specific area of interest in an outpatient clinic setting. And when you can see a lesion and aim at it, you've got a major advantage in terms of knowing what's really going on, as opposed to conventional blind, systematic biopsies.

Which patients are the best candidates for this approach?
We initially offered targeted biopsy to difficult diagnostic cases, i.e., men with prior negative biopsies, but persistently elevated PSA. The other men for whom we recommend targeted biopsy are those in active surveillance for apparent low-risk prostate cancer. After several years of experience, however, we now try to accommodate any man who comes to us seeking the new method for his biopsy.

Dr. Leonard S. Marks, M.D. - UCLA UrologistHow is targeted biopsy a useful tool in "watchful waiting" of men with low-risk prostate cancer?
We know that unlike most other cancers, prostate tumors are often not lethal and may never require treatment. The problem has always been finding reliable ways of predicting which patients need treatment and which ones can simply be monitored. Using this more accurate biopsy approach, men who are believed to have low-risk tumors can be followed with greater confidence. If a man is in the active-surveillance program and his targeted biopsy is negative, that offers a degree of reassurance not previously possible, potentially enabling us to spare more men of the pain, risks, and side effects of surgery or radiation therapy.

Where is this technology headed?
Right now it's like the year 1900 in the automobile industry: lots of activity, lots of experimentation, lots of companies attempting to enter the business. I anticipate much consolidation in the future. There are going to be major advances in both software and hardware. Imaging modalities are likely to improve to the point that we can identify the lesions better. The future belongs to better imaging, better targeting, better software that allows easier MR-ultrasound fusion - or fusion of real-time ultrasound with some other imaging modality that we don't know about yet - and improvements in the hardware to make this less cumbersome. I see nothing but rapid progress ahead.





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