The Relationship Between Imaging Scores of Primary Tumors in Prostate Cancer Patients and Risk Stratification

1324 Purpose: The aim of this study was to evaluate the relationship of imaging scores of primary tumors of newly diagnosed prostate cancer patients with clinical and histopathological risk factors.Materials and Methods: The data of 64 prostate cancer patients who underwent Ga-68 PSMA PET/MRI for primary staging prior to radical prostatectomy (RP) were analyzed retrospectively. The index lesions (IL) were detected histopathologically on RP specimens. The PSMA uptake intensity on the PET/MRI correlates of index lesions were scored visually according to the miPSMA expression scoring system: uptake < blood pool (BP) as 0, ≥ BP and < liver as 1, ≥ liver and < parotid gland (PG) as 2 and ≥ PG as 3 [1]. Patients were categorized according to the visual scores as low (0-1) and high (2-3) score groups. PIRADS scores of ILs on MRI, total imaging scores (PIRADS + miPSMA, TIS), Gleason scores/grades (GS/GG), pathological T stages, total PSA, PSA density (PSAd), free to total PSA ratios (F/T) of patients were recorded. Patients were divided into two groups according to the D’amico risk stratification system: i) low-intermediate risk group (LIR) and ii) high risk group (HR). Statistical analyses were performed on SPSS version 23.0.Results: The characteristics of patients were shown in Table 1. The ratio of patients in D’amico HR group was significantly higher in patients with high miPSMA scores compared to those with low miPSMA scores (78.8 % vs 38.7 %, p=0.002). miPSMA scores had moderate positive correlations with GG, GS, total PSA, PSAd and moderate negative correlation with F/T (p<0.001, for all). PIRADS scores had weak correlation with miPSMA score (r=0.36, p=0.003) and it did not demonstrate significant correlations with total PSA and F/T (p=0.07 and p=0.74, respectively). In ROC curve analysis, TIS had the AUC of 0.83 (p<0.001), higher than PIRADS (0.77) and miPSMA (0.76), for detecting the HR. The cut-off value of 6 had sensitivity of 73.7% and specificity of 76.9%. Total PSA and PSAd had significantly higher and F/T had significantly lower median values in patients with high miPSMA compared to those with low miPSMA and in patients with high TIS (≥6) compared to those with low TIS (<6) (Table 2).Conclusions: The visual assessments with miPSMA and total imaging scores were significantly associated with clinical and histopathological risk factors in patients with prostate cancer. The combination of PIRADS and miPSMA scores seems to be a promising tool for predicting high risk patients.Reference ADDIN EN.REFLIST 1. Eiber, M., et al., Prostate cancer molecular imaging standardized evaluation (PROMISE): proposed miTNM classification for the interpretation of PSMA-ligand PET/CT. Journal of Nuclear Medicine, 2018. 59(3): p. 469-478.