The major advances that have greatly improved our understanding of prostatic disease are significant revision of prostatic anatomy, development of serum assays for prostate specific antigen (PSA), and improvements in imaging techniques, specifically the development of high-resolution transrectal ultrasound (TRUS) and magnetic resonance (MR) imaging.
In McNeal's zonal concept, the prostate is composed of three major glandular zones (transition, central, and peripheral zones), and one non-glandular region (anterior fibromuscular stroma). The peripheral zone constitutes 70% of prostatic glandular tissue and is located at the posterior, lateral and apical aspects of the gland, and 70% to 80% of all prostate cancers originate in the peripheral zone.
The classic appearance of prostate cancer on TRUS is a hypoechoic lesion in the peripheral zone. However, only 60% of prostate cancers are hypoechoic and only 20-30% of all hypoechoic lesions are cancers. Hypoechoic lesions that mimic cancer are inflammation, atrophy, infarction and benign hyperplasia. About 40% of prostate cancers are hyperechoic or isoechoic. In such cases, other TRUS findings such as capsular bulge, asymmety of echogenecity, periprostatic fat irregularity, and loss of normal echo of seminal vesicles may help detect prostate cancers. Prostate cancers that locate in the transition or central zone and diffuse cancers infiltrating entire peripheral zone or entire gland do not appear with classical finding of prostate cancer on TRUS.
Color/power Doppler ultrasound (CDUS/PDUS) is a simple technique to demonstrate the vascularity of a lesion. CDUS/PDUS may be helpful in differentiating malignant from benign prostatic lesions by demonstrating hypervascular nature of the lesion and may help to identify an appropriate site for biopsy. Contrast-enhanced TRUS may add specificity in prostate cancer detection.
Whenever a prostate cancer is suspected, systematic prostatic biopsy is necessary. There are controversies regarding optimal number of biopsy cores, and various schemes are used obtaining from 6 to 13 cores reporting increasing rate of cancer detection with increasing number of biopsy cores. Currently most commonly used system is 12 core-scheme with 6 medial cores and 6 lateral cores. In patients with very high PSA density level, we may substitute 6-core biopsy for 12-core scheme. If there is focal lesions at TRUS, additional cores are obtained. After biopsy, CDUS/PDUS may show active bleeding through the needle track that can be controlled by compression with transducer head.