Ultrasonography - Prostate and Testes
About Ultrasonography
Ultrasound waves consist of a mechanical disturbance of a medium such as air. The disturbance passes through the medium at a fixed speed causing vibration. The rate at which the particles vibrate is the frequency, measured in cycles per second or hertz (Hz). Sound becomes inaudible to the human ear above about 20 kHz, or 20 thousand Hertz, and is then known as ultrasound. Diagnostic imaging uses much higher frequencies, in the order of megahertz (MHz), or millions of Hertz.
The higher the frequency used the better the resolution. The latter is the ability to distinguish two adjacent objects. However, as the frequency increases, more of the ultrasound beam is absorbed by the target and the beam cannot penetrate so far. For this reason, higher frequencies (7.5 MHz) are used to provide good detail of superficial organs such as the prostate, testes, thyroid and breast, and lower frequencies (3.5 MHz) for examination of the abdomen.
While ultrasonography or sonography is the use of sound waves for radiological purposes, it uses no x-ray or any radiation, is safe, and is performed in the office without anesthesia. In male urology, the prostate and testes are near body surfaces and can be imaged with ultrasonography for aiding diagnosis and for biopsying of abnormal findings.
Fluid or a mass around the scrotum (tissue around the testicle) can make the physical exam of the testis impossible. Ultrasonography can send sound waves through the scrotum and help view the testis to look at hernias, fluid collections (hydroceles or spermatoceles), abnormal veins (varicocele), and possible cancer. For prostate disease, ultrasonography can be used through a rectal probe.
Transrectal ultrasonography is routinely used for prostate biopsies in patients with abnormal PSA levels to look for abnormalities and aid in precise biopsy needle placement. Prostate ultrasonography can also be used to perform peri-prostatic pain blocks (prior to biopsy or procedure) and obtain accurate prostate size measurements for enlarged prostate or prostate cancer treatments. Patients should be given antibiotics before the procedure.
When a transrectal probe is used for pelvic sonography, cancers show up by asymmetric densities within the prostate. This procedure is not the most sensitive means of establishing a diagnosis, but it is useful for documenting the degree of extension of the tumor into the seminal vesicles.
Some Advantages of Ultrasonography
Conclusion
As far as prostatic disease is concerned, transrectal ultrasonography cannot be considered to be a primary element of the diagnosis, with the same value as a digital rectal examination (DRE) or a Prostate Specific Antigen (PSA) assay. The main value of ultrasonography is to allow for well-targeted prostatic biopsies.
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