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Erschienen in:
01.07.2015 | Original Article
Usefulness of MRI-assisted metabolic volumetric parameters provided by simultaneous 18F-fluorocholine PET/MRI for primary prostate cancer characterization
Erschienen in: European Journal of Nuclear Medicine and Molecular Imaging | Ausgabe 8/2015
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Purpose
The aim of this study was to determine the usefulness of MRI-assisted positron emission tomography (PET) parameters provided by simultaneous 18F-fluorocholine (FCH) PET/MRI for characterization of primary prostate cancer.
Methods
Thirty patients with localized prostate cancer (mean age 69.4 ± 6.7 years) confirmed by biopsy were prospectively enrolled for simultaneous PET/MRI imaging. The patients underwent 18F-FCH PET/MRI 1 week before undergoing total prostatectomy. Multiple parameters of diffusion-weighted MRI [minimum and mean apparent diffusion coefficient (ADCmin and ADCmean)], metabolic PET [maximum and mean standardized uptake value (SUVmax and SUVmean)], and metabolic volumetric PET [metabolic tumor volume (MTV) and uptake volume product (UVP)] were compared with laboratory, pathologic, and immunohistochemical (IHC) features of the prostate cancer specimen. PET parameters were divided into two categories as follows: volume of interest (VOI) of prostate by SUV cutoff 2.5 (SUVmax, SUVmean, MTVSUV, and UVPSUV) and MRI-assisted VOI of prostate cancer (SUVmaxMRI, SUVmeanMRI, MTVMRI, and UVPMRI).
Results
The rates of prostate cancer-positive cases identified by MRI alone, 18F-FCH PET alone, and 18F-FCH PET/MRI were 83.3, 80.0, and 93.3 %, respectively. Among the multiple PET/MRI parameters, MTVMRI showed fair correlation with serum prostate-specific antigen (PSA; r = 0.442, p = 0.014) and highest correlation with tumor volume (r = 0.953, p < 0.001). UVPMRI showed highest correlation with serum PSA (r = 0.531, p = 0.003), good correlation with tumor volume (r = 0.908, p < 0.001), and it was significantly associated with Gleason score (p = 0.041). High MTVMRI and UVPMRI values were significant for perineural invasion, lymphatic invasion, extracapsular extension, seminal vesicle invasion, and positive B-cell lymphoma 2 (Bcl-2) expression (all p < 0.05).
Conclusion
Simultaneous 18F-FCH PET/MRI demonstrated a better diagnostic value for localized prostate cancer detection than each individual modality. MRI-assisted metabolic volumetric PET parameters (MTVMRI and UVPMRI) provided more accurate characterization of prostate cancer than conventional PET and MRI parameters.