前立腺癌におけるマルチパラメトリックMRIの役割

The role of multiparametric MRI in prostate cancer

前立腺特異抗原（prostate-specific antigen：PSA）検診の普及により，転移のない初期の前立腺癌発見が増加している。そのような初期の症例に系統的な前立腺生検が行われた結果，臨床的にあまり重要でない癌も検出されるようになってきた。

Prostate cancer has been increasing recently. There are many treatment options for prostate cancer, such as active surveillance, surgery, radiation therapy, endocrine therapy, and chemotherapy, depending on risk classification. The diagnostic imaging of prostate cancer using magnetic resonance imaging（MRI）has become widely used for the detection, localization and tumor staging for prostate cancer. In prostate MRI, T2 weighted images, T1 weighted images, contrast enhanced imaging, diffusion weighted images and apparent diffusion coefficient map are normally taken. The method of evaluating these MRI imaging method in combination referred to as a multi-parametric MRI（mpMRI）. In 2015, PI-RADS（Prostate Imaging Reporting and Data System）was upgraded to version 2, a standardized reporting system for evaluating clinically significant prostate cancer. It is designed to promote global standardization and reduce the variation in acquisition, interpretation, and reporting of prostate mpMRI examinations. These mpMRI examinations are essential for the detection and determination of treatment options in prostate cancer. We focus on diagnostic imaging of prostate cancer, especially mpMRI.