In biological imaging the use of the different imaging techniques have yet to be explored. Currently, there are two topics of importance. The first topic is perfusion. In prostate cancer, the degree of vascularisation appears to correlate with aggressive behaviour and risk of metastasis. In prostate cancer approximately two times as many microvessels exist in the malignant tissue compared to normal tissues. Furthermore, in benign tissues the capillaries are restricted for the most part to the periglandular stroma immediately adjacent to the epithelium, whereas the distribution in carcinoma appears to be more random. Differences in perfusion have been shown to correlate with active prostate cancer areas. Dynamic contrast-enhanced MRI is able to show the microvessel density (MVD) in the prostate. Second is the metabolic activity in prostate cancer. The ratios of choline and creatine (normal value 0.22 +/- 0.13 ppm) reveals metabolic active prostate cancer tissue. Increased choline and/or a reduced citrate indicate prostate cancer. The ratio of choline and creatine-to citrate is related to the Gleason score of the tumour. Concluding, MRI and MRS allow combined structural and metabolic evaluation of prostate cancer location, aggressiveness and stage. The same could be performed using combined CT and PET. Sutinen et al found a clear evidence for detecting areas with [11C] choline in prostate cancer using PET. To our knowledge no data exist comparing [11C] choline PET and MRS in prostate cancer. The technology for biological imaging remains in evolution, and continued advances in accuracy and can be expected.