MRI and MR voiding cystourethrography in the evaluation of male primary bladder neck obstruction: preliminary experience

Abstract

Purpose: Evaluation of male with primary bladder neck obstruction (PBNO) using MRI and MR voiding cystourethrography (MR-VCU) to study both anatomical aspects of bladder neck and urethral lumen.

Methods: In this retrospective study 21 male patients (mean age 33 ± 14) with urodynamic diagnosis of PBNO and 5 healthy volunteers ((mean age 28 ± 2) as control group were enrolled. Both patients and control group underwent 1.5 T MRI. Sagittal and oblique coronal Turbo-Spin-Echo T2-weighted scans were performed. Only patients underwent MR voiding cystourethrography (MR-VCU) performed with T1-weighted spoiled 3D gradient-echo sagittal acquisitions. Bladder lumen was filled with contrast-material-enhanced urine. Blinded test by two radiologists was performed to evaluate causes of bladder outlet obstruction evaluating MR-VCU. Anatomical MRI features of both control group and patients were compared in consensus by senior radiologist and urologist using the analysis of variance (ANOVA) test.

Results: MRI allowed evaluation of the bladder neck muscular structures. We found 4 groups of PBNO patients: 52% hypertrophy of posterior lip of bladder sphincter; 20% asymmetry of lateral portion of bladder sphincter; 14% bladder neck cyst; 14% showed normal aspect of bladder neck. Comparison between the control group and first and second PBNO groups was considered statistically significant (p < 0.05) with diagnostic accuracy of 87%. Only 13 patients (61%) were able to perform MR-VCU and radiologists always made the diagnosis of PBNO.

Conclusion: MRI together with MR-VCU provides useful anatomical and functional information in the study of bladder neck and urethral lumen. These preliminary results suggest that MRI could substitute for standard cystourethrogram in patients with PBNO.

Keywords: Magnetic resonance imaging; Male; Urinary bladder neck obstruction; Urination; Urodynamics.