Prostate cancer: a comparative study of 11C-choline PET and MR imaging combined with proton MR spectroscopy

Prostate cancer is difficult to visualise in its early stages using current imaging technology. The present study aimed to clarify the utility of 11C-choline PET for localising and evaluating cancer lesions in patients with prostate cancer by conducting a prospective comparison with magnetic resonance (MR) imaging combined with proton MR spectroscopy.

PET and MR imaging combined with proton MR spectroscopy were performed in 20 patients with prostate cancer. Correlations among the metabolite ratio of choline + creatine to citrate (Cho+Cr/Ci) on MR spectroscopy, serum PSA and maximum standardised uptake value (SUVmax) of (11)C-choline were assessed. The location of the primary lesion was assessed by the site of SUVmax and the laterality of the highest Cho+Cr/Ci ratio and confirmed by examination of surgical pathology specimens (n=16).

PET exhibited a diagnostic sensitivity of 100% (20/20) for primary lesions, while the sensitivities of MR imaging and MR spectroscopy were 60% (12/20) and 65% (13/20), respectively. Weak linear correlations were observed between SUVmax and serum PSA (r=0.52, p<0.05), and between SUVmax and Cho+Cr/Ci ratio (r=0.49, p<0.05). Regarding the localisation of main primary lesions, PET results agreed with pathological findings in 13 patients (81%) (kappa=0.59), while MR spectroscopy results were in accordance with pathological findings in eight patients (50%) (kappa=0.11).

This preliminary study suggests that 11C-choline PET may provide more accurate information regarding the localisation of main primary prostate cancer lesions than MR imaging/MR spectroscopy. A further clinical study of 11C-choline PET in a large number of patients suspected of prostate cancer will be necessary to determine the clinical utility of 11C-choline PET in patients who clinically require biopsy.