Contrast specific imaging in the detection and localization of prostate cancer.

Prostate cancer (PCa) is the most common cancer in elderly men and is one of the most important causes of death from cancer in men. The diagnosis of PCa is based on a combination of digital rectal examination, PSA and transrectal ultrasound (TRUS). However, this combination does not reach the accuracy of detection and localization necessary for proper decisions on treatment methods. Therefore, biopsies are performed in all cases for which the suspicion of PCa is raised. Even with biopsies, staging and grading of PCa is far from optimal. More accurate imaging is necessary to improve the biopsy sampling, the goals being to replace systematic biopsies by a targeted approach and to improve staging and grading of PCa. Ultrasound imaging of the prostate remains the first choice of imaging to visualize the prostate, however, gray-scale ultrasound imaging has an accuracy of about 50-60% for the detection of PCa and TRUS used for local staging has an even lower accuracy. The development of PCa is associated with changes in the metabolism of tumor cells, and therefore with changes in the blood perfusion of the involved tissue. This paper focuses on contrast specific imaging techniques to visualize these changes in blood perfusion. Techniques such as color and power Doppler imaging, and contrast enhanced imaging techniques using color and power Doppler, harmonic imaging and intermittent imaging are discussed.