Abstract
ObjectiveThe objective of this study was to assess the accuracy of 68Ga-PSMA-11 PET/MRI, 18F-PSMA-1007 PET/CT, 68Ga-PSMA-11 PET/CT, and multiparametric (mp)MRI for the delineating of dominant intraprostatic lesions (IPL).Materials and methods35 patients with organ-confined prostate cancer who were assigned to definitive radiotherapy (RT) were divided into three groups based on imaging techniques: 68Ga-PSMA-PET/MRI (n = 9), 18F-PSMA-PET/CT (n = 16) and 68Ga-PSMA-PET/CT (n = 10). All patients without PSMA-PET/MRI received an additional mpMRI. PSMA-PET-based automatic isocontours and manual contours of the dominant IPLs were generated for each modality. The biopsy results were then used to validate whether any of the prostate biopsies were positive in the marked lesion using Dice similarity coefficient (DSC), Youden index (YI), sensitivity and specificity. Factors that can predict the accuracy of IPLs contouring were analysed.ResultsDiagnostic performance was significantly superior both for manual and automatic IPLs contouring using 68Ga-PSMA-PET/MRI (DSC/YI SUV70%—0.62/0.51), 18F-PSMA-PET/CT (DSC/YI SUV70%—0.67/0.53) or 68Ga-PSMA-PET/CT (DSC/YI SUV70%—0.63/0.51) compared to mpMRI (DSC/YI—0.47/0.41; p < 0.001). The accuracy for delineating IPLs was not improved by combination of PET/CT and mpMRI images compared to PET/CT alone. Significantly superior diagnostic accuracy was found for large prostate lesions (at least 15% from the prostate volume) and higher Gleason score (at least 7b) comparing to smaller lesions with lower GS.ConclusionIPL localization was significantly improved when using PSMA-imaging procedures compared to mpMRI. No significant difference for delineating IPLs was found between hybrid method PSMA-PET/MRI and PSMA-PET/CT. PSMA-based imaging technique should be considered for the diagnostics of IPLs and focal treatment modality.
Highlights
Accurate delineation of the malignant intraprostatic lesions (IPLs) can be performed using advanced molecular imaging procedure as positron emission tomography (PET) technology and multiparametric magnetic resonance imaging (MRI)
Based on the criteria for dominant IPLs, we selected for the correlation analysis 17 prostate lesions identified with 68Ga-PSMA-PET/MRI, 33 IPLs detected with 18F-PSMA-PET/CT and mpMRI, and 21 IPLs diagnosed with 68Ga-PSMA-PET/CT and mpMRI (Table 1)
The correlation indices, including the mean Dice similarity coefficient (DSC), Youden index (YI), sensitivity and specificity for each contouring value are summarized in Table 2. SUV70% was defined as the best automatic contouring method showing the highest DSC and YI values both for 68Ga-PSMA-PET/CT and 18F-PSMA-PET/CT
Summary
Accurate delineation of the malignant intraprostatic lesions (IPLs) can be performed using advanced molecular imaging procedure as positron emission tomography (PET) technology and multiparametric (mp) MRI. Previous studies showed superior accuracy of [ 11C]-choline-PET/CT images compared to MRI for delineating IPLs [1,2,3,4]. Recent studies evaluated the hybrid imaging tool 68Ga-PSMA-PET/ MRI and 18F-PSMA-PET/MRI for the diagnostics of primary or recurrent prostate cancer (PCa) [6, 11,12,13]. As reported by Kim et al, the 18F-PSMA-PET/MRI provided higher detection rate of PCa than other imaging procedures [13]. RT concepts for primary PCa using image-guided focal boost treatment need an optimal diagnostic algorithm for localizing malignant IPLs. The present study evaluates diagnostic performance for identifying IPLs analysing the 68Ga-PSMA-PET/MRI, as well as 18F-PSMA-PET/CT and 68Ga-PSMA-PET/CT alone or in combination with mpMRI using the prostate biopsy specimens for the validation of diagnostic accuracy of images. Parameters that can potentially predict the accuracy of PSMA-PET and MRI images for delineating IPLs were analysed
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