Potential of asphericity as a novel diagnostic parameter in the evaluation of patients with Ga-68-PSMA-HBED-CC PET-positive prostate cancer lesions

Background: The aim of this study was to evaluate the diagnostic value of the asphericity (ASP) as a novel quantitative parameter, reflecting the spatial heterogeneity of tracer uptake, in the staging process of patients with Ga-68-PSMA-HBED-CC positron emission tomography (PET)-positive prostate cancer (PC). In this study, 37 patients (median age 72 years, range 52-82 years) with newly diagnosed PC, who received a Ga-68-PSMA-HBED-CC PET fused with computed tomography (Ga-68-PSMA-PET/CT), a magnetic resonance imaging (MRI) of the prostate, and a core needle biopsy (within 74.2 8 +/- 80.2 days) with an available Gleason score (GSc) were extracted from the local database. The ASP and the viable tumor volume (VTV) was calculated using the rover software (ABX GmbH, Radeberg, Germany), a segmentation tool for automated tumor volume delineation. Additionally, parameters including total lesion binding rate (TLB), maximum, mean and peak standardized uptake value (SUVmax/mean/peak), prostate-specific antigen (PSA), D'Amico classification, and prostate imaging reporting and data system (PI-RADS) were analyzed. Results: The ASP mean differed significantly (p = 0.05) between the different GSc groups: GSc 6-7: 11.9 +/- 4.8%, GSc 8: 25.5 +/- 4.8%, GSc 9-10: 33.3 +/- 6.8%. A significant correlation between ASP and GSc (rho = 0.88; CI 0.78-0.94; p < 0.05) was measured. The ASP enabled an independent (p > 0.05) prediction of the GSc. A moderate correlation was measured between ASP and the D'Amico classification (rho = 0.6; CI 0.32-0.78; p < 0.05). The VTV showed a moderate correlation with the SUVmax (rho = 0.58; CI 0.32-0.76; p < 0.05) and the GSc (rho = 0.51; CI 0.23-0.72; p < 0.05). Conclusion: The asphericity in Ga-68-PSMA-PET could represent a promising novel quantitative parameter for an improved non-invasive tumor staging of patients with PC.