“State of the art” transrectal ultrasound imaging in the assessment of prostatic disease

Abstract

Three major developments have occurred in recent years which have increased our understanding of prostatic disease: a major reassessment of the anatomy of the prostate, the development of the serum assay for prostate-specific antigen, and developments in prostatic imaging. The prostate gland has traditionally been regarded as an organ with a relatively simple anatomical structure, based on a system of lobes, as proposed by Lowsley (1912). Lowsleyapos;s concept was, however, based on observations of fetal prostate glands and this system cannot now be accepted. A zonal system of anatomy of the prostate was initially proposed by McNeil in 1969 and was fully described in 1981. This concept has been supported by work by Blacklock and Boushill (1977). In McNeil's system the prostate is considered as three glandular zones, transition, central and peripheral, and one non-glandular region, the anterior fibromuscular stroma. The urethra and ejaculatory ducts pass through these zones (Fig. 1). It is important to appreciate this concept of prostatic anatomy as these zones can be identified by transrectal ultrasound with state of the art ultrasound transducers and magnetic resonance (MR) imaging. In the young adult prostate, the transition zone constitutes about 5% of prostatic glandular tissue and is located on both sides of the prostatic urethra; it is in this zone that benign hyperplasia develops. The transition zone is separated from the central and peripheral zones of the prostate by the surgical capsule.