Imaging in urethral stricture disease: an educational review of current techniques with a focus on MRI

Urethral stricture disease refers to narrowing of the urethral lumen obstructing the flow of urine. Urethral strictures can significantly impact daily life due to incontinence, incomplete emptying, hesitancy, and increased risk of urinary tract infections. Imaging is central to the evaluation of suspected urethral stricture, as assessment of stricture length and severity is crucial for guidance of surgical management. The currently employed modalities include radiography, chiefly retrograde urethrography (RUG) and voiding cystourethrography (VCUG); magnetic resonance urethrography (MRU); and sonourethrography (SUG). MRU has become a recent focus of research as it provides high spatial resolution, multiplanar capacity, and soft tissue type differentiation for evaluation of periurethral compartments and concurrent soft tissue defects. The protocol for MRU has evolved over the years to now include dynamic micturition imaging and image reconstruction options. In this review, we discuss each of the imaging modalities used in the diagnosis and evaluation of urethral stricture and provide an overview of literature on MRU over the last decade, including suggested indications that have not yet been incorporated into current guidelines. We delineate scenarios where special diagnostic imaging beyond radiography is beneficial, providing examples from our practice and description of our techniques for each modality.