Color Doppler Ultrasound and Targeted Biopsy
This article will discuss an alternative type of imaging, called color Doppler ultrasound (CDU). Unfortunately, CDU followed by targeted biopsy is available in only a few centers around the United States. Even so, this article will expound the many advantages of CDU for the diagnosis and staging of prostate cancer.
Imaging with CDU utilizes two components; grey scale imaging and color Doppler evaluation of vascularity. With CDU, cancerous lesions appear as a dark spot. In addition, cancer can show increased blood vessel density, or “hypervascularity.” High-resolution CDU readily identifies tumors over 5 mm in diameter. Cancers that are visible on CDU are more likely to be clinically significant (Gleason 4+3=7 or above). Hypervascularity tends to indicate tumors with a higher grade.
PSA, Gland Volume, and Diagnosis
Using an arbitrary PSA level as a trigger for doing a 12-core random biopsy casts such a broad net that overdiagnosis becomes inevitable. Men’s prostates vary greatly in size—so the amount of PSA they produce varies greatly. Rather than recommending a 12-core random biopsy to every man with a slightly elevated PSA, my policy is to use a relatively low PSA threshold of 2.5 as an initial trigger to recommend a CDU evaluation. However, in men with risk factors such as family history or African-American descent, I use an even more conservative PSA cut point of 2.0 to recommend a CDU. In older men who tend to have larger prostate glands, a threshold of 4.0 is reasonable.
The first step should be to measure the size of the prostate with CDU. If a patient’s PSA is higher than expected for the individual’s prostate size, it increases the likelihood that an underlying high-grade prostate cancer may be present (“The PSA Blood Test” explains how to calculate a normal PSA level with allowance for the prostate’s size). Men whose PSA levels are in the normal range for their prostate size should not be subjected to invasive diagnostic procedures unless other suspicious findings are uncovered during the performance of the CDU.
Questions that Color Doppler Ultrasound Can Answer:
● Where is the tumor located within the gland?
● Does the tumor remain confined within the prostate?
● What is the tumor’s diameter in millimeters? Does the size of the lesion detected by imaging coincide with the length of cancer reported in the targeted needle biopsy as reported by the pathologist?
● Is tumor size or vascularity on sequential scanning increasing over time for men who are on active surveillance?
Final Thoughts on Prostate Imaging
Prostate imaging dramatically reduces the need for random biopsy. If an abnormality is detected by imaging, a targeted biopsy provides information that is of higher quality using far fewer stabs of the needle. Imaging should precede random needle biopsy. When a biopsy is required, it should be targeted rather than random.
Duke Bahn, MD is the Director of the Prostate Institute of America. Certified by the American Board of Radiology, his special areas of interest are the early detection and staging of prostate cancer using color-Doppler ultrasound with tissue harmonics. He is also a pioneer in using cryotherapy, as both a primary and salvage treatment for prostate cancer. His published data was the impetus for obtaining Medicare approval for cryotherapy as a viable treatment for prostate cancer. Dr. Bahn has held many academic and professional appointments, including clinical professor of urology, Keck School of Medicine, University of Southern California.