Correlation between 68-Gallium-PSMA PET/CT and multiparametric MRI in evaluation of primary prostate carcinoma

Prostate cancer is the second common cancer in men worldwide. The main diagnostic workup for prostate cancer includes Digital rectal examination, assessing serum concentration of Prostate Specific Antigen (PSA) and trans rectal ultrasonography (TRUS) guided biopsy for histological confirmation. Multi parametric MRI is considered standard for local staging of prostate cancer and also helps to guide biopsy by accurately localizing lesions. 68-Gallium-PSMA PET/ CT is an emerging modality for local and systemic staging of prostate cancer and its utility to target biopsy is also being explored. Hence this study aims to compare the diagnostic accuracy of 68-Gallium-PSMA PET/CT and multipara metric MRI for intra prostatic localization of prostate cancer foci. 20 treatment naïve patients with biopsy proven prostate cancer were retrospectively selected. All patients had undergone 68-Gallium-PSMA PET/CT, multipara metric MRI and 12 core TRUS guided biopsy. 68-Gallium-PSMA PET/CT, multipara metric MRI were independently interpreted by a nuclear medicine physician and a radiologist who were unaware of the result of the other modality. 12 core TRUS guided biopsy results were noted.12 sector map of prostate was adapted to correlate imaging findings with 12 core biopsy results. Diagnostic accuracy (sensitivity, specificity, positive predictive value and negative predictive value) of 68-Gallium-PSMA PET/CT, multipara metric MRI for was compared for intra prostatic localization with histopathology being gold standard. 240 sectors (n=20) were analyzed on 68-Gallium-PSMA PET/CT and multipara metric MRI respectively. Diagnostic performance of both the modalities was assessed one on one using 12 core biopsy results as gold standard. The sensitivity, specificity, PPV, NPV of PSMA PET/CT and multipara metric MRI were 62%, 61%, 59%, 64% and 56%, 77%, 68%, 66% respectively. The diagnostic accuracy of multipara metric MRI was found to be slightly greater than 68-Gallium-PSMA PET/CT in the intra prostatic localization of cancer foci. (author)