Pseudolayering of urine in the bladder

Case contributed by Carlos Felipe Teixeira Lôbo

Presentation

Right hip pain for the past 2 years. Hip deformity at physical examination. No previous history of renal diseases and had a normal glomerular filtration rate.

Patient Data

Age: 75 years
Gender: Female

The exam was performed in a right lateral decubitus position due difficult patient positioning. Axial images were flipped 90° clockwise for better appreciation. MRI revealed diffuse joint space narrowing and bone edema of the right femoroacetabular joint, acetabular protrusion and disruption of the medial acetabular wall. A displaced fracture of the right pubis was also noted.

A curious finding not related to the clinical issue of the patient was observed inside the bladder on post-contrast MRI, which consisted of three sharply marginated layers of different signal intensities. The correlation with the pre-contrast images excluded the possibility of different sediments inside the bladder.

Case Discussion

This phenomenon is called pseudolayering of the gadolinium inside the urinary bladder. The layers are not real anatomically. They are signal intensity abnormalities, yet sharply demarcated. It happens because the progressive addition of gadolinium to a mixture, such as urine, reduces its T1W and T2W values in a nonlinearly and even paradoxically way. So:

  • the top non-dependent layer, located at the patient’s left side, has no gadolinium, hence signal intensity is dark on T1WI, as expected for pure urine
  • the middle layer has a relatively low concentration of gadolinium, mixed with urine. At these levels, the T1W-shortening effect predominates over the T2W-shortening effect and the bright signal intensity appears on both T1W and T2WI
  • the bottom dependent layer, located at the patient’s right side, has the urine with the highest concentration of gadolinium. At these concentrations, gadolinium promotes an extreme T2-shortening effect, which predominates over the T1W-shortening, leading to a markedly low signal intensity on both T1W and T2WI

 

Co-authors: Renata Vidal Leão and Marcelo Bordalo Rodrigues. 

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Case information

rID: 72275
Published: 21st Nov 2019
Last edited: 21st Nov 2019
Inclusion in quiz mode: Included

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