Correlation of gallium-68 prostate-specific membrane antigen positron emission tomography - Computed tomography/magnetic resonance imaging with histopathology characteristics in carcinoma prostate patients undergoing radical prostatectomy.

Introduction: Gallium-68 prostate-specific membrane antigen positron emission tomography (⁶⁸Ga-PSMA PET) is being increasingly used in patients with prostate cancer (PCa) for the staging and detection of lymph node (LN) metastases, despite a lack of prospective, validated evidence. We aimed to investigate the relationship between the PSMA PET findings (maximum standardized uptake [SUV_max] value) and the final histopathology results (Gleason Grade [GG], and LN positivity) in patients undergoing radical prostatectomy.

Methods: This is a single centre, prospective, observational study of 63 consecutive eligible patients treated at a tertiary care centre in India. Patients underwent ⁶⁸Ga-PSMA PET computed tomography with fusion magnetic resonance imaging for staging, followed by a Transrectal ultrasound guided prostate biopsy. All patients underwent robotic-assisted radical prostatectomy with extended pelvic LN dissection as per the standard protocol. Clinical parameters and SUV_max values were collected and analysed.

Results: The median preoperative prostate specific antigen (PSA) was 15.0 ng/ml (interquartile range: 9.4-28.0). A statistically significant correlation was observed between the PSA values and the SUV_max uptake (P < 0.001). Additionally, there was a statistically significant correlation between the SUV_max of the prostatic lesion and the GG on the radical prostatectomy specimens (P = 0.025), and SUV_max of LN and LN involvement (P < 0.001). The sensitivity and specificity of the ⁶⁸Ga-PSMA PET scan were 77.8% and 88.7%, respectively.

Conclusions: SUVmax of the PCa lesion and the GG Group on the final histopathology correlates significantly. There is an increased SUV uptake in Gleason's Score (GS) 8, 9 tumours as compared to GS 6 and 7.