PET/CT and choline: diagnosis and staging.

As prostate cancer is the most prevalent form of cancer in men and constitutes the third most common cause of cancer associated deaths, early diagnosis of primary prostate cancer and accurate staging influencing the appropriate choice of therapy is crucial. PET and PET/CT using [11C]- and [18F]-labelled choline derivates are increasingly being used for imaging primary and recurrent prostate cancer. The value of [11C]- and [18F]choline PET and PET/CT in patients with biochemical recurrence of prostate cancer has been evaluated in many studies and shows an increasing importance. Morphological imaging techniques such as TRUS, CT and MRI (including functional imaging tools) have shown only limited accuracy for the diagnosis of primary prostate cancer. Molecular imaging techniques such as PET and PET/CT may improve the detection rate and localization of primary prostate cancer. The potential of PET/CT using [11C]- and [18F]-labelled choline derivates for the diagnosis of primary prostate cancer has been assessed in a lot of studies with partly controversial results. [11C]- and [18F]choline PET and PET/CT demonstrated moderate sensitivity for the detection of primary prostate cancer, which depends on the tumour configuration. Furthermore the detection rate is limited by a considerable number of microcarcinomas that can often not be visualized due to partial volume effects. Therefore small and in part rind-like tumours can often not be detected. Additionally, specificity of [11C]- and [18F]choline PET and PET/CT is limited as differentiation between benign prostatic changes like prostatitis, prostatic hyperplasia and high-grade intraepithelial neoplasia (HGPIN) is not always possible. At the present time, the routine use of PET/CT with [11C]- and [18F]-labelled choline derivates can not be recommended as a first-line screening procedure for primary prostate cancer in men at risk. However, choline PET and PET/CT may be useful in preparation of a focused re-biopsy in patients suffering from clinically suspected prostate cancer with repeatedly negative prostate biopsies. In the future [11C]- and [18F]choline PET and PET/CT may also be helpful in patient stratification with respect to primary surgery and radiation therapy.