Impact of Endorectal Coil Use on Extraprostatic Extension Detection in Prostate MRI: A Retrospective Monocentric Study.

Abstract

Rationale and objectives: Accurate preoperative mpMRI-based detection of extraprostatic extension (EPE) in prostate cancer (PCa) is critical for surgical planning and patient outcomes. This study aims to evaluate the impact of endorectal coil (ERC) use on the diagnostic performance of mpMRI in detecting EPE.

Materials and methods: This retrospective study with prospectively collected data included participants who underwent mpMRI and subsequent radical prostatectomy for PCa between 2007 and 2024. Participants were divided based on ERC use on mpMRI: MRI without ERC and with ERC. Surgical pathology reports were used to determine the patients with pathologic EPE on whole-mount histopathology. One radiologist evaluated mpMRI using an in-house (National Cancer Institute [NCI]) EPE grading system. Logistic regression (LR) analyses were conducted to identify significant predictors of pathologic EPE, including ERC use and NCI EPE grades.

Results: 934 men (median age: 62 years [IQR = 57-67]) were included. For NCI EPE grade≥1, ERC MRI group (n = 612) had higher NPV (91% [320/353] vs. 83% [166/200], p = 0.01) and sensitivity (75% [101/134] vs. 62% [56/90], p = 0.04) compared to non-ERC group (n = 322). For NCI EPE grade = 3, ERC MRI group had higher NPV (83% [452/546] vs. 75% [221/294], p = 0.01) and accuracy (80% [492/612] vs. 74% [238/322], p = 0.03). In multivariable LR, higher NCI EPE grades were strong independent predictors of pathologic EPE, irrespective of ERC use (NCI EPE grade 2 with ERC: odds ratio [OR] = 2.01, p = 0.04; without ERC: OR = 5.63, p<0.001, NCI EPE grade 3 with ERC: OR = 4.53, p<0.001; without ERC: OR = 5.22, p = 0.002).

Conclusion: ERC improves sensitivity, NPV, accuracy of EPE detection with mpMRI at different NCI EPE thresholds. NCI EPE grading system remains the stronger independent predictor of pathologic EPE regardless of ERC use.