MRI artifact (flow void between urinary bladder and bladder diverticulum)

Case contributed by Chris O'Donnell
Diagnosis certain


Severe right hip pain. MRI for evaluation of possible osteoarthritis. Long term urinary symptoms

Patient Data

Age: 65 years
Gender: Male

Preliminary coronal imaging...


Preliminary coronal imaging of the pelvis prior to dedicated hip sequences

Thick-walled bladder with a left paracystic fluid-filled mass showing a "flow void" - black streak passing between the bladder and the cystic mass.

Ultrasound confirms a thick-walled trabeculated bladder with multiple small right-sided diverticula (at least 3) and the large left diverticulum identified on MRI.

Case Discussion

Moving protons in water cause so-called "flow artefact" on T2 weighted images since they are not refocused by the 180 degree spin echo pulse.  This artefact can be useful to determine patency of tubular structures such as blood vessels, aqueduct of Sylvius and in this case to confirm that a left paracystic mass is connected to the bladder via a flow void of urine passing between the true bladder lumen and a diverticulum.

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