Medical imaging of prostate cancer

The clinical significance of prostate cancer is increasing markedly with an increased population of aged persons and Westernized behavior patterns. Accordingly, the role of prostate imaging is also becoming important in the early diagnosis of prostate cancer. Transrectal prostate ultrasound (TRUS) is used for the estimation of prostate volume as well as the detection of prostate cancer, seen as focal hypoechoic lesions. Almost all prostate tissue biopsies are performed under the guidance of TRUS. One of the important issues in prostate imaging is the visualization of suspected prostate cancer lesions. In order to obtain detailed information regarding a suspected prostate lesion, contrast-enhanced imaging is utilized, using microbubbles and elastography. In addition, magnetic resonance imaging-ultra sonography (MRI-US) fusion imaging, in which the ultrasound machine archives magnetic resonance (MR) images and facilitates MRI-US fusion imaging-guided biopsy, has been revealed to be superior to conventional ultrasound-guided biopsy. Prostate MR is usually performed in patients with confirmed prostate cancer, after prostate biopsy for the evaluation of tumor staging or follow-up changes after chemotherapy, hormone therapy, or radiation therapy. In particular, the evaluation of seminal vesicles is crucial for accurate identification of tumor staging. Advanced functional MR techniques, including diffusion-weighted imaging, dynamic contrast-enhanced imaging, and MR spectroscopy, also have potential in the localization of prostate cancer. In summary, the role of prostate imaging in the diagnosis and localization of prostate cancer is increasing. Advanced technologies in ultrasound and MR imaging may have important roles in localization of prostate cancer and image-guided biopsy. Key w ords: Prostate; Ultrasonography; Magnetic resonance imaging; Biopsy; Image fusion