MRI fi ndings 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.


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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 superficial coil was performed in a 1.5T magnetic fi eld equipment.We obtained multiplanar T1-and 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 (Fig- ure-1).The affected musculature was isointense on T1-and 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.

DISCUSSION
PBNO was fi rst described in men by Marion (1), a condition wherein the bladder neck fails to open adequately during voiding, resulting in increased striated sphincter activity or obstruction of urinary fl ow in the absence of another anatomic obstruction, such as that caused by benign prostatic enlargement in men or genitourinary prolapse in women (2,3).
Men typically present with symptoms for years before a correct diagnosis of PBNO is made.PBNO can present with a variety of symptoms including voiding or obstructive symptoms (decreased force of stream, hesitancy, intermittent stream, incomplete emptying), storage or irritative symptoms (frequency, urgency, urge incontinence, nocturia), or a combination of  ABBREVIATIONS ADC: apparent diffusion coeffi cient MRI: magnetic resonance imaging PBNO: primary bladder neck obstruction both.Occasionally, the initial presentation may be urinary retentions (3).Presenting symptoms appear to be similar in men and women, with a combination of voiding and storage symptoms being common (4).Currently PBNO is diagnosed primarily by videourodynamics and cystourethroscopy, but the increasing use of MRI can introduce new imaging fi ndings (5).

Figure 1 -
Figure 1 -Coronal (a), sagittal (b), and axial (c), T2-weighted MRI images showing exuberant concentric hypertrophy of the muscular planes surrounding the urethra along its complete extension (arrows).This characteristic fi nding resembled the bulb of a sphygmomanometer in "a" and "b", and a doughnut in "c".

Figure 2 -
Figure 2 -(a) Axial diffusion sequence showed a ring-like hyperintensity of the peri-urethral hypertrophied muscles.(b) The axial ADC map demonstrated hypointensity in the affected muscles.In both images the doughnut sign is clearly depicted (arrows).