For decades the random 12-core biopsy has been the mainstay for diagnosing prostate cancer. Unfortunately, there is a slew of problems that comes with random biopsy, including misdiagnosis, infection, and impotence. Over the last 10-15 years, prostate imaging has improved tremendously. Today, prostate imaging allows men to avoid the random 12-core biopsy and get more accurate results. Both the 3 Tesla multiparametric MRI (3T MP-MRI) and the color Doppler ultrasound are safe, accurate ways to detect and monitor prostate cancer.
Diagnosing Ambiguous Lesions
When a prostate specific antigen (PSA) test comes back high, imaging should be the next step. Prostate imaging can “see” all sorts of noncancerous lesions including scar tissue, areas of active prostatitis, and nodular areas from benign prostatic hyperplasia (BPH). Imaging can also detect prostate cancer. More importantly, imaging with 3T MP-MRI and color Doppler ultrasound can accurately pin point the cancer’s location in the prostate allowing for a targeted biopsy (see below).
Lesion characteristics that a raise concern that cancer may be present are:
- Location in the peripheral zone rather than the transition zone
- Over a centimeter in size
- Bulging the prostate capsule
- Increased blood flow
- Low diffusion coefficient
- Growth on sequential scanning
Targeted Rather than Random Biopsies
When a suspicious lesion is detected, a targeted biopsy (a limited number of cores aimed directly at the lesion) is typically recommended. Imaging with 3T MP-MRI or color Doppler ultrasound directs the biopsy to the area of concern in the prostate. Lesions that are biopsy-negative, meaning they show no sign of cancer, or lesions that show low-grade cancer (Gleason 6), can be monitored without any treatment. If high-grade disease is diagnosed, further testing, staging, and treatment discussion is necessary.
Imaging for Monitoring Low-Grade Cancer
Studies clearly show that low-grade cancers (SKY stage) can be safely monitored without any immediate treatment in a process called active surveillance. The most commonly used active surveillance protocol relies on periodic random biopsy. Random biopsies use a spring-loaded needle gun to extract samples from various “random” locations in the prostate gland. Because of the location of the prostate (just under the bladder, wrapped in the nerves that control erections, and in close proximity to the rectum) random biopsies can result in serious infections and impotence (difficulty or inability to get erections). The random biopsy is also prone to missing high-grade cancers that are in under-sampled locations in the gland.
Fortunately, sequential imaging using 3T MP-MRI and color Doppler ultrasound accurately detects high-grade disease and overlooks low-grade disease, while avoiding the potential side-effects that come with random biopsy. This spares men the shock of an unnecessary cancer diagnosis and, in many cases, unwarranted treatment. As stated above, if while on active surveillance a new lesion develops or becomes an area of potential concern, a targeted biopsy should be discussed with a medical professional.
Scanning at a Center of Excellence
There are still relatively few centers that perform prostate imaging at the level of quality we are discussing. For example, three components are required to achieve reliable results with 3T MP-MRI:
- State-of-the-art, 3 Tesla hardware
- Technicians who are precisely trained in how to perform prostate imaging
- Physicians carefully trained specifically in the interpretation of prostate imaging
Similarly, accurate color Doppler ultrasound imaging should only be performed by physicians who are experienced in treating prostate cancer.
Despite these great improvements in prostate cancer imaging technology, many doctors are not yet aware (or comfortable using) this new technology. Every effort must be made to raise general awareness among patients and doctors alike about the advantages of imaging over random biopsy techniques in men with high PSA levels and in men diagnosed with low-grade cancer pursuing active surveillance.