Quantitative evaluation of bone metastases from prostate cancer with simultaneous [18F] choline PET/MRI: combined SUV and ADC analysis.

Objective: To quantitatively analyze bone metastases from prostate cancer and correlate the apparent diffusion coefficients (ADCs) and standardized uptake values (SUVs).

Methods: Fifty-five patients with biopsy-proven prostate cancer or suspected recurrent prostate cancer were examined with simultaneous [18F] choline Positron emission tomography (PET)/MRI at 3 T. In 11 patients, thirty-two PET-positive bone lesions could be identified that were located in the field-of-view of the Diffusion weighted imaging-sequence. Region-of-interest and volume-of-interest analyses were performed to measure the mean and minimal ADCs and to assess maximum and mean SUVs of every bone lesion. Correlations between maximum and mean SUVs and mean and minimal ADCs were calculated.

Results: The SUVmax of all lesions was 5.5±3.1 (mean±SD). The SUVmean was 1.8±0.9. The mean ADC (ADCmean) of all lesions was 0.67±0.13×10(-3) mm2/s. The minimal ADC (ADCmin) of all lesions was 0.56±0.14×10(-3) mm2/s. There was a moderate but significant inverse correlation of SUVmax vs. ADCmean with a correlation coefficient of -0.4 (p=0.02). There was also a significant inverse correlation of SUVmax vs. ADCmin with r=-0.41 (p=0.02).

Conclusion: Our initial results demonstrate a moderate but significant inverse correlation between increased choline metabolism and ADC values of bone metastases from prostate cancer. Further research on a multimodality approach using simultaneous PET/MRI in bone metastasis of prostate cancer seems to be justified.