Statistical Analysis
The sensitivity, specificity, positive predictive value (PPV), negative
predictive value (NPV), positive likelihood ratio (PLR), negative
likelihood ratio (NLR), and the accuracy of mpMRI,68Ga-PSMA PET/MRI, and combined imaging for the
detection of the index tumour were calculated by creating crosstabs.
Correlations between continuous measures were determined using
Spearman’s (rs) correlation. The Cohen’s kappa
coefficient (κ) was calculated to define agreement between mpMRI and
68(Ga)-PSMA PET/MRI. The cut-off values of clinical parameters were
determined by using receiver operating characteristics (ROC) curve
analysis and Youden’s index. Diagnostic accuracy of imaging modalities
was assessed using the area under the curve (AUC), and 95% confidence
intervals (95% CI) were calculated by ROC analysis. Combined imaging
was also added to the ROC analysis as a third method. Accordingly, if
either imaging modalities were positive, then the combined imaging was
considered positive, and if both imaging modalities were negative, then
the combined imaging considered negative. Differences in the sensitivity
and specificity of mpMRI and 68Ga-PSMA PET/MRI were
analysed using the McNemar test. A significance level of 5% was used.
All analyses were performed using SPSS software, version 15.0 (SPSS
Inc., Chicago, IL, USA).