Purpose: To characterize intermediate and high-risk prostate carcinomas with measurements of standardized uptake values(SUVs) and apparent diffusion coefficient (ADC) values by means of simultaneous [18F] choline PET/MRI.

Materials and Methods: 35 patients with primary prostate cancer underwent simultaneous [18F] choline PET/MRI. Fromthese, 21 patients with an intermediate and high risk constellation who were not under ongoing hormonal therapy wereincluded. Altogether 32 tumor lesions with a focal uptake of [18F] choline could be identified. Average ADC values (ADCaver)minimum ADC values (ADCmin) as well as maximum and mean SUVs (SUVmax, SUVmean) of tumor lesions were assessed withvolume-of-interest (VOI) and Region-of-interest (ROI) measurements. As a reference, also ADCaver,ADCminand SUVmaxandSUVmeanof non-tumorous prostate tissue were measured. Statistical analysis comprised calculation of descriptiveparameters and calculation of Pearson’s product moment correlations between ADC values and SUVs of tumor lesions.

Results:Mean ADCaverand ADCminof tumor lesions were 0.9460.2261023mm2/s and 0.6560.2161023mm2/s,respectively. Mean SUVmaxand SUVmeanof tumor lesions were 6.362.3 and 2.660.8, respectively. These values were ineach case significantly different from the reference values (p,0.001). There was no significant correlation between themeasured SUVs and ADC values (SUVmaxvs. ADCaver:R=20.24, p = 0.179; SUVmaxvs. ADCmin:R=20.03, p = 0.877; SUVmeanvs. ADCaver:R=20.27, p = 0.136; SUVmeanvs. ADCmin:R=20.08, p = 0.679).

Conclusion: Both SUVs and ADC values differ significantly between tumor lesions and healthy tissue. However, there is nosignificant correlation between these two parameters. This might be explained by the fact that SUVs and ADC valuescharacterize different parts of tumor biology.