RARE-MR-urography in the diagnosis of upper urinary tract abnormalities in children

Abstract

RARE-MR-urography (Rapid Acquisition with Relaxation Enhancement) is a fast MR imaging technique (6.4 s/acquisition) that selectively depicts fluid by heavy T2-weighting. From 9/1989 to 11/1990, RARE-MR urograms were prospectively evaluated in the diagnosis of upper urinary tract abnormalities in 55 children. The method is performed in several planes and combined with a coronal, T1-weighted spin-echo sequence. Forty out of 42 kidneys with dilated renal pelvis, and 21 out of 24 dilated ureters were identified, only the mildly dilated ones were missed. Even in non-functioning kidneys the urinary tract was clearly depicted by RARE-MR-urography. However, no differentiation could be made with this technique between vesicoureteral reflux and non-refluxing dilatation of ureter and/or renal pelvis. All 19 pelviureteric obstructions and all eight renal duplications with a dilated segment were identified. RARE-MR-urography is a new tool for diagnosing urinary tract abnormalities in children without having to employ ionizing radiation, contrast media, or general anesthesia. A dilated urinary tract can be shown in one image displaying the entire urinary system, similar to excretory urography. The technique is presently not able to provide the information of voiding cystourethrography or renal scintigraphy, nor is it as easy to perform as ultrasound. However, in certain cases it may replace excretory urography.

MR Urography in the Diagnosis of Urinary Tract Obstruction

“…6b). This was expected to happen because, as we said before, MRU produces fluid-specific images [6, 8]. …”

“…Urinary tract obstruction results in static distended systems and is easily depicted [1]. Therefore we did not try to produce diuresis with furosemide, as distended systems produce clear fluid-specific images (water pictures) [6]. …”

Breath‐Hold Projection Magnetic Resonance‐Cholangio‐Pancreaticography (MRCP): a New Method for the Examination of the Bile and Pancreatic Ducts

“…Our minimum number of different projections was four. When adjusted angulations and various slice thicknesses were applied, the maximum number was by [10][11][12][13][14][15]. The total amount of time for all these acquisitions was then about 5 min.…”

“…In 1984 it was demonstrated that single-shot modification RARE can be used to depict only water-containing structures such as the spinal canal, kidney, cysts, etc. This technique was termed RAREhydrography, or, depending on its applications, RAREmyelography (10) or RARE-urography (11) mainly applied in neuroradiology and pediatric urology. Singleshot RARE has been implemented on a 1.0 T whole body-imager (Magnetom Impact, Siemens, Erlangen Germany) allowing multiplanar single-shot acquisitions with a variable slice thickness.…”

MR Urography With Dynamic 3d Mip Aided Detection- Diagnostic Significance Value in Suspected Pelvicaliectasis Confirmation

“…[5,2,3,6,7,8,4] The most common MR urographic techniques for displaying the urinary tract can be divided into two categories: Static-fluid MR urography and Excretory MR urography. Static-fluid MR urography makes use of heavily T2-weighted sequences to image the urinary tract as a static collection of fluid, can be repeated sequentially (cine MR urography) to better demonstrate the ureters in their entirety and to confirm the presence of fixed stenosis, and is most successful in patients with dilated or obstructed collecting systems.…”