Comparison of static-fluid or excretory magnetic resonance urography with computed tomography urography for visualization of nondilated renal pelvises and ureters in healthy Beagles

OBJECTIVE To assess the usefulness of magnetic resonance urography (MRU) for the visualization of nondilated renal pelvises and ureters in dogs and to compare our findings for MRU versus CT urography (CTU). ANIMALS 9 healthy Beagles. PROCEDURES Dogs underwent CTU, static-fluid MRU, and excretory MRU, with ≥ 7 days between procedures. Contrast medium was administered IV during CTU and excretory MRU, whereas urine in the urinary tract was an intrinsic contrast medium for static-fluid MRU. For each procedure, furosemide (1 mg/kg, IV) was administered, and reconstructed dorsal plane images were acquired 3 minutes (n = 2) and 7 minutes (2) later. Images were scored for visualization of those structures and for image quality, diameters of renal pelvises and ureters were measured, and results were compared across imaging techniques. RESULTS Excretory MRU and CTU allowed good visualization of the renal pelvises and ureters, whereas static-fluid MRU provided lower visualization of the ureters. Distention of the renal pelvises and ureters was good in excretory MRU and CTU. Distention of the ureters in static-fluid MRU was insufficient compared with that in CTU and excretory MRU. Distinct artifacts were not observed in CTU and excretory MRU images. Static-fluid MRU images had several mild motion artifacts. CLINICAL RELEVANCE Our findings indicated that excretory MRU with furosemide administration was useful for visualizing nondilated renal pelvises and ureters of dogs in the present study. When performing MRU for the evaluation of dogs without urinary tract dilation, excretory MRU may be more suitable than static-fluid MRU.

PEMERIKSAAN STATIC FLUID MAGNETIC RESONANCE UROGRAPHY PADA ANAK DENGAN DUGAAN OBSTRUKSI TRAKTUS URINARIUS

Background : Static fluid Magnetic Resonance Urography (MRU) treats the urinary tract as a static column of fluid, using one of a variety of T2-weighted sequences that exploit the long T2 relaxation time of urine. It does not require the excretion of contrast material and is therefore useful for demonstrating the collecting system and ureter of an obstructed urinary tract. Static fluid MRU provides good morphology visualization and multiplanar three-dimensional reconstruction capability. Aim of study : To display the excellence of static fluid MRU in visualization of dilatated urinary tract segments in pediatric cases with suspectedurinary obstruction. Methods : Nine pediatric patients with suspected obstructive uropathy (as suggested by ultrasound) were included in this case study. The examinations were performed with 1.5T MR scanners using static fluid T2-weighted MRU sequence. Ultrasound examinations were done forall patients. Voiding cystourethrogram was done for 3 patients. Results : Eight studied patients had dilated collecting systems. Static fluid MRU can provide detailed structural assessment of dilatatedcollecting systems. It was superior to ultrasound in evaluation of obstructive double collecting system, ureteral ectopia, ureteral obstructionand massive hydroureteronephrosis.