What are the cross sectional imaging features of prostate adenocarcinoma?
Prostate adenocarcinoma arises most commonly from the peripheral zone (70%) and less commonly from the transitional zone (20%) and central zone (10%). It appears as a focal mass in the prostate gland. On US, it is hypoechoic or, less often, isoechoic relative to surrounding prostate gland tissue and sometimes has increased blood flow on Doppler US. On CT, it is usually not well visualized but may sometimes be seen as a focal soft tissue attenuation enhancing mass, particularly when large in size or extending into surrounding structures. On MRI, it typically has low-intermediate T1-weighted and low T2-weighted signal intensity relative to normal peripheral zone (see Figure 39-2 ), restricts diffusion on diffusion-weighted images, and enhances early with subsequent rapid washout.