Superiority of Ga-PSMA-11 PET/CT over mpMRI for lateralization accuracy of diagnosing intra-glandular prostate cancer lesions: avoiding fluke targeting.

Objective: The aim of this study was to compare the diagnostic accuracy of Ga-PSMA-11 PET/CT and multiparametric MRI (mpMRI) in detecting unilateral and bilateral intra-glandular prostate cancer lesions.

Methods: A retrospective analysis was conducted on 73 prostate cancer patients diagnosed via biopsy, all of whom underwent both Ga-PSMA-11 PET/CT and mpMRI prior to surgery. Two independent readers, blinded to each other's results and to pathology findings, evaluated the imaging modalities to make a diagnosis of unilateral (left or right) or bilateral lesions for suspected prostate lesions. Histopathological findings from a 12-core transrectal ultrasound-guided biopsy and radical prostatectomy served as reference standards. The accuracy of both imaging modalities in determining unilateral and bilateral intra-glandular prostate cancer was assessed through receiver operating characteristic curve analysis. Additionally, factors influencing diagnostic discordance between the two modalities were evaluated.

Results: A total of 73 patients were included in the final analysis, comprising 34 with unilateral lesions and 39 with bilateral lesions. Among these, 35 patients underwent radical prostatectomy, revealing 22 cases of bilateral lesions and 13 cases of unilateral lesions [Kappa = 0.76 (P < 0.001)]. The lateral diagnostic accuracy of Ga-PSMA-11 PET/CT, based on pathological results from biopsy or prostatectomy, was 80.82% (59/73) and 82.86% (29/35), respectively. These values were significantly higher than those of mpMRI, which demonstrated an accuracy of 54.79% (40/73, P < 0.001) and 40% (14/35, P < 0.001), respectively. Concordance between Ga-PSMA-11 PET/CT and mpMRI for the lateralization accuracy was poor (kappa = 0.015, P < 0.05). When both imaging modalities provided consistent lateralization results (39/73), concordance with pathological findings reached 87.18% (34/39). However, concordance with pathological results was significantly higher for Ga-PSMA-11 PET/CT (76.47%, 26/34) compared to mpMRI (20.59%, 7/34). Further analysis revealed that an SUVmax > 3.95 for Ga-PSMA-11 PET/CT and a PI-RADS score ≥ 4 for mpMRI were independent factors influencing lateral diagnostic concordance.

Conclusion: The Ga-PSMA-11 PET/CT demonstrated significantly higher lateralization accuracy than mpMRI in intra-glandular prostate cancer. There was considerable inconsistency in the diagnostic outcomes between Ga-PSMA-11 PET/CT and mpMRI, and in cases of discordance, Ga-PSMA-11 PET/CT was notably more accurate. SUVmax > 3.95 and PI-RADS score ≥ 4 were critical factors influencing the correct lateralization accuracy when the results from Ga-PSMA-11 PET/CT and mpMRI were inconsistent.