The prostate is a gland the size of a walnut which lies in the male pelvis in front of the rectum and around the outlet of the bladder.
To examine the prostate, the doctor inserts a finger into the patient’s rectum and can then feel the back surface of the prostate through the wall of the rectum. This exam is used to help detect any abnormality.
If serious suspicion of abnormality exists, biopsy of the prostate is the next step. This is the process of placing a needle into the prostate to obtain tissue for microscopic examination. The microscopic exam will tell if there is any cancer in the sample.
Nowaday the most usual method of biopsying the prostate uses a slim ultrasound probe passed into the rectum. The ultrasound produces an image of the gland which helps guide the doctor to the areas to biopsy. A special needle is then used to remove a tiny piece of the prostate for examination for cancer. Presently, this is the standard method and should be the main approach when the decision to biopsy the prostate is made. However, we are learning that there are more limitations to the standard approach than previously thought. This method of biopsying the prostate, although very useful, can miss some cancers. A new generation of the prostate biopsy technology is now available and has the promise of missing fewer cancers.
The standard approach to prostate biopsy was improved in the 1990’s when studies showed that using an ultrasound to target certain areas of the prostate was better than relying on finger-guided biopsies alone. Since that time, most urologists use a grid system with 12 to 13 zones to target. They use the ultrasound to facilitate taking a biopsy sample from each of those areas from the rectal side of the prostate. However some cancers still cannot be seen or are difficult to recognize under ultrasound. Therefore, the goal of the standard approach is to SAMPLE every zone of the prostate, rather than to directly TARGET lesions that might be cancers. This can result in missing some cancers. See Figure 1.
Figure 1: Multiple prostate biopsies can miss a cancer.
X = Biopsy
The prostate is a 3–dimensional object, which causes the standard approach to have another limitation. Because the trans-rectal ultrasound probe is at the rectal/posterior surface of the prostate, the other (anterior) side tends not to be biopsied unless the whole needle is pushed into the prostate before taking a tissue sample. See Figure 2. In addition, as men age, the prostate will often enlarge which increases the distance from the rectal side to the anterior side. Luckily, most prostate cancers do not develop on the deeper/anterior side. But when they do, the standard method can miss them.
Figure 2: Limitation to Biopsy Anterior Prostate
With recent advances in imaging and technology, we are now able to further minimize the risk of missing cancers. The MRI can now see the abnormal prostate tissue and the ultrasound can guide the biopsy needle to areas of the prostate. Fusing these technologies allows us to use the advantages of each.
Greater Boston Urology was the first group in Massachusetts to adopt the MRI-Fused Ultrasound Guided Biopsy. Our updated state-of-the-art Uronav system allows us to overlay the MRI images on top of ultrasound images so, as we view the prostate by ultrasound during the biopsying procedure, the suspicious areas revealed by MRI will also be visualized. Essentially, we build a 3-D computer model of the MRI images of the patient’s prostate and overlay it on the ultrasound images to allow the biopsies to accurately target suspicious regions. We can record the actual position of each biopsy in the 3-D prostate model and store this information for future reference.
It is clear from our data and from others that cancers are more likely to be detected by this new method than by standard ultrasound biopsies. These cancers also tend to be the more aggressive in nature, which makes them particularly important to detect. The new method provides men with the information they need to opt for the appropriate treatment. Also those patients with negative biopsies can be more assured that they are less likely to harbor cancer.
Our review of patient data since 2011 has shown us how to best use this technology and who will most benefit from it.
You may benefit from the MRI-Fused Ultrasound Guided Biopsy if you have had a previous standard biopsy with one or more of these results:
1) No cancer found but your PSA continues to rise
2) High Grade Prostatic Intraepithelial Neoplasia (HGPIN)
3) Atypical Small Acinar Proliferation (ASAP)
4) Atypical Glands Suspicious for Carcinoma
5) You are now on Active Surveillance
Please feel free to call our office to schedule a consultation with one of our urologists who specializes in the MRI-Ultrasound Fusion Biopsy Procedure.