Magnetic resonance urography (MR urography) is a MRI study that predominantly used to image congenital abnormalities of the urinary system. There are two types of MR urography: static fluid-sensitive urography that is heavily T2-weighted to image the fluid-filled urinary system and excretory MR urography that is T1-weighted that image the urinary system after intravenous gadolinium administration 4.
Procedure
Indications
to demonstrate the urinary system or the level of obstruction in a poorly functioning kidney or urinary system obstruction
congenital abnormalities of the urinary system
assessment of the renal transplant donor 4
Technique
patient lies down in supine position with an empty urinary bladder. A moderately filled bladder may be preferred when the urinary bladder is of interest 4
MR sequences that can be used are: single-shot fast spin-echo (SSFSE), half-Fourier rapid acquisition with relaxation enhancement (RARE), and single-shot turbo spin echo (SSH-TSE) 4
other measures such as intravenous or oral hydration, diuretics, or using a compression band may help to distend the urinary system further.
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after this, excretory MR urography is performed by administering 0.1 mmol/kg intravenous gadolinium. The patient is imaged at 10 to 20 minutes using a breath-hold, T1-weighted, 3D gradient echo sequence 4
contrast administration can enhance the T2* decay in the gradient echo sequence, suppressing signal intensity from the urine. This problem can can solved by administering lower dose of gadolinium. However, low gadolinium dose may compromise the signals from soft tissues 4
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