MRI findings in Marion's disease: the bulb and the doughnut signs.

A 77-year-old female presented to our facility with a fi ve-year history of progressive urinary bladder retention and voiding diffi culties. She underwent a pelvic magnetic resonance imaging (MRI) examination as a part of her lower urinary tract symptoms evaluation, and for treatment planning. MRI with a torso phased-array superfi cial coil was performed in a 1.5T magnetic fi eld equipment. We obtained multiplanar T1and T2weighted pre-contrast sequences, with and without fat suppression techniques, axial diffusion weighted images, axial apparent diffusion coeffi cient (ADC) map, and multiplanar T1-weighted fat suppressed images after the administration of intravenous gadolinium. MRI revealed an exuberant concentric hypertrophy of the entire urethra. This characteristic imaging fi nding resembled a bulb of a sphygmomanometer on the sagittal and coronal planes, and a doughnut on the axial ones (Figure-1). The affected musculature was isointense on T1and slightly hyperintense on T2-weighted images compared with unaffected muscles. The diffusion sequence showed restriction to free water molecules movements, making the hypertrophied muscles hyperintense on this sequence and hypointense on the ADC map (Figure-2). Additionally this patient also exhibited a marked concentric hypertrophy of the internal anal sphincter muscle, probably related to the same bladder neck neuropathological mechanism. This latter fi nding was previously misdiagnosed in another facility as a rectal tumor. After the intravenous contrast administration, there was slight enhancement of the hypertrophied muscle. The combination of the MRI fi ndings together with the patient ́s symptoms and urodynamic testing was consistent with the diagnosis of primary bladder neck obstruction (PBNO) due to severe muscular hypertrophy.