Prostate cancer is the most commonly diagnosed cancer among men and remains the second leading cause of cancer death in men. In 2009, approximately 192,000 in the United States (US) and 9600 in the Netherlands (NL) men were diagnosed with prostate cancer, and 27,000 (US) and 2400 (NL) men died from this disease. The prostate specific antigen (PSA) blood test disseminated 20 years ago, and helped shift the disease stage at the time of diagnosis to a much lower and potentially more curable stage. However, early detection of prostate cancer remains a source of uncertainty and controversy.
Recently, it has been established that PSA and systematic transrectal ultrasound (TRUS) testing can reduce prostate cancer mortality. In a large intention to screen trial, Schroder et al showed a mortality reduction of 20% (improved trial showed 30%). The Schroder clinical workflow had two major problems: low specificity of the PSA test and biopsy as subsequent gold standard. The results showed that 1410 men would need to be screened and 48 cases of prostate cancer need to be treated to prevent one death from prostate cancer.
Magnetic resonance imaging (MRI) can be used to increase specificity, guide biopsy, and improve staging. Prostate MRI has evolved since its first application in the late 80’s. This millennium saw the start of high resolution 3D T2 weighted sequences and 3D dynamic contrast enhanced MR (DCEMR), later followed by 3D diffusion weighted imaging (DWI). Localization of prostate cancer can be performed at a high diagnostic accuracy and has been applied in a first clinical application: MR guided intensity modulated radiotherapy planning. Tanimoto et al. using a combination of T2 weighted, DWI, and DCEMR concluded that in patients with a PSA level over 4 ng/ml unnecessary biopsy can be avoided without missing prostate cancer. A recent development is to perform MR guided biopsy of MR determined tumor suspicious regions after having a positive MR. This approach proved to be an accurate method to detect clinically significant prostate cancer in men with repeat negative biopsies and increased PSA levels.
Computer aided diagnostic tools will become essential if mass application of MR would become a viable option. Reporting the huge volume of prostate MR accurately and efficient will require skills and the right tools including computerized analysis techniques that help to reduce oversight and interpretation errors.