Three dimensional ultrasound and prostate cancer.

Three-dimensional ultrasound (3-D US) is a non-invasive method of producing whole volume images of solid structures. Early work on prostate imaging identified several advantages over 2-D imaging with a good ability to detect intraprostatic lesions. Several 3-D transrectal ultrasound (3-D TRUS) systems are now available for prostate imaging. Initial work using gray scale ultrasound appears promising with reported overall staging accuracies of up to 94%. These results were favourable when compared to other modalities for local staging of prostate cancer. Several adjuncts to 3-D gray scale TRUS have been investigated. A greater sensitivity for cancer detection has been achieved with the addition of power colour Doppler and contrast agents. Further clinical applications for 3-D TRUS include assessing placement of brachytherapy seeds and for cyroablation techniques. Computer enhancement with image registration has shown that 3-D US images can be manipulated to derive more information. Although the results of gray scale imaging alone or with adjuncts and post processing appear promising, these techniques remain largely experimental.