We assessed the performance of parametric fusion PET/MRI based on 11C-choline PET/CT and apparent diffusion coefficient (ADC) maps derived from diffusion-weighted MRI for the identification of primary prostate cancer.
METHODS: 11C-choline PET/CT and MRI were performed in 17 patients with untreated primary prostate cancer, followed by prostatectomy. Registration of in vivo imaging with histology was achieved using a mutual-information objective function and by performing ex vivo MRI of the prostatectomy specimen (obtained at 3 T) and whole-mount sectioning with block-face photography as intermediate steps. Data analysis included volumetrically registered whole-mount histology with Gleason scoring, 11C-choline, and ADC data (obtained at 1.5 T). Volumes of interest were defined on the basis of histologically proven tumor tissue to calculate tumor-to-benign prostate background ratios (TBRs) for 11C-choline, ADC, and a derived fusion PET/MRI parameter calculating the quotient of 11C-choline over ADC (PCHOL/ADC).
RESULTS: Fifty-one tumor nodules were identified at pathology. The TBRs for 11C-choline (P < 0.05) and PCHOL/ADC (P < 0.005) were significantly higher in prostate cancers with a Gleason score of ≥3 + 4 than with a Gleason score of ≤ 3 + 3 disease and controls. For Gleason ≥ 3 + 4, the ADC TBRs were significantly lower than controls and Gleason ≤ 3 + 3 disease (P < 0.05). The absolute value of TBRs obtained from Gleason ≥ 3 + 4 cancers increased from ADC to 11C-choline PET/CT and from 11C-choline PET/CT to PCHOL/ADC, with each step being statistically significant.
CONCLUSION: Our data indicate that parametric PET/MRI using PCHOL/ADC improves lesion-to-background contrast (TBRs) of Gleason ≥ 3 + 4 disease, compared with 11C-choline PET/CT or diffusion-weighted MRI, and thus hold promise that parametric imaging performed on hybrid PET/MRI may further improve identification and localization of significant primary prostate cancer.
Written by:
Park H, Wood D, Hussain H, Meyer CR, Shah RB, Johnson TD, Chenevert T, Piert M. Are you the author?
Department of Radiology, University of Michigan, Ann Arbor, MI, USA.
Reference: J Nucl Med. 2012 Apr;53(4):546-51.
doi: 10.2967/jnumed.111.091421
PubMed Abstract
PMID: 22419751
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