Detection of aggressive primary prostate cancer with ¹¹C-choline PET/CT using multimodality fusion techniques

The aim of the study was to assess whether ¹¹C-choline PET/CT could identify high-risk primary adenocarcinoma of the prostate. Methods: ¹¹C-choline PET/CT and transpelvic MRI were performed in 14 patients with untreated localized primary adenocarcinoma of the prostate, followed by radical prostatectomy as a form of primary monotherapy within 14 d of in vivo imaging. To allow accurate coregistration of whole-mount histology with in vivo imaging, additional ex vivo MR images of the prostatectomy specimen were obtained. Nonlinear 3-dimensional image deformations were used for registrations of PET/CT, MRI, and histology. Volumes of interest from tumor and benign tissue were defined on the basis of histology and were transferred into coregistered ¹¹C-choline PET/CT volumes to calculate the mean (T _(mean)/B) and maximum (T_(max)/B) ratio of tumor to benign prostate background. On the basis of MIB-1/Ki-67 expression in tumor tissues represented on a tissue microarray, we assessed whether ¹¹C-choline uptake correlated with local Gleason score and tumor proliferation. Results: Histology confirmed 42 tumor nodules with Gleason scores between 3 1 2 and 4 1 4, with volumes ranging from 0.03 to 12.6 cm³. T_(mean)/B (P < 0.01) and. T_(max)/B (P < 0.001) ratios were significantly increased in high-Gleason score (≥4 + 3) lesions versus 3 + 4 and lower disease but failed to distinguish between 3 + 4 disease versus 3 + 3 and lower. T_(mean)/B and T_(max)/B ratios were significantly increased in tumors with an MIB-1/Ki-67 labeling index greater than or equal to 5% (P < 0.01). Conclusion: On the basis of our preliminary data using ratios of tumor to benign prostate background, ¹¹C-choline preferentially identified aggressive primary prostate cancer.