Contrast-Enhanced Ultrasound for the Prostate

Abstract

Imaging of the prostate can be performed using different imaging techniques and has several applications in the evaluation of benign and malignant prostate diseases. Many imaging techniques are used to detect and follow up abnormalities of the prostate such as prostatitis, abscesses, benign prostate hyperplasia, and prostate cancer, or to investigate symptoms that can be caused by the prostate such as hemospermia or male lower urinary tract symptoms (LUTS). Other utilities of prostate imaging are guidance of prostate biopsies or to support prostate cancer treatment using image-guided therapy. One of the most important applications for imaging of the prostate is the detection and staging of prostate cancer. The incidence of prostate cancer is globally increasing, and different disease stages of prostate cancer require different treatment modalities. 1 In 2007, an estimated 220,000 new prostate cancer cases will occur, and it will be the second leading cause of cancer death for men in the United States. 2 To prevent underor overtreatment as a consequence of incorrect staging, an accurate detection-staging cascade is necessary. Consequently an accurate detection-staging cascade will improve patient selection for the different existing treatment modalities resulting in better treatment outcomes. Sensitivity and specificity of the existing imaging techniques used to date to detect prostate cancer is low. Transrectal ultrasonography (TRUS) of the prostate is the most widely used technique for imaging of the prostate to detect cancer. Even in combination with digital rectal examination and prostate biopsies, however, the sensitivity of TRUS in detecting prostate cancer is low. Sextant transrectal ultrasoundguided biopsies are reported to have a sensitivity of 50–85% in the detection of prostate cancer. 3 O’Dowd et al. found that 26% of men with initial biopsies negative for prostate cancer showed positive biopsies for prostate cancer within 1 year after the first series. 4 That is why the search for more sensitive and specific imaging techniques for prostate cancer continues . The latest development in the detection and staging of prostate cancer is perfusion imaging of the prostate. Tumor growth is associated with angiogenesis, increased vascularity, and abnormal blood flow patterns because of an increased need of oxygen and nutrients due to expansive growth of malignant tissue. 5 Perfusion imaging is able to visualize these hemodynamic properties. This chapter is dedicated to the application of contrast-enhanced ultrasound of the prostate to improve detection, monitoring, treatment, and follow up of prostate cancer. We will address the following questions: What is the contribution of contrast-enhanced ultrasound for the detection and staging of prostate cancer? Can CEUS support the existing imaging modalities and what will future developments bring?