6 MR UROGRAPHY Advantages over CT Urography: Elimination of ionizing radiationNon Ionic ContrastContrast ResolutionNon Contrast imaging (T2 Imaging)Disadvantages vs. CT Urography:Claustro/ImplantsCT: 15 min vs. MR: 45 minSpatial resolution ( 3-6 mm)Calcifications not seenCostUncooperative patientCT is the modality of choice for acute symptoms
7 PATIENT PREPARATION 250 ml IV normal saline solution Furosemiode/Lasik PO Water (30 minutes prior to MRI)Furosemiode/LasikNon Dilated SystemsGlucagonMinimized PeristalsisIntravenous Contrast (Multihance)Single DoseLasik and Saline/Water improves urine production, dilutes urine.Furosemiode improves distention and opacification in non dilated system(better for static-fluid Urogram)
8 MR UROGRAPHY PROTOCOL Pre Contrast T2* SSFP Axial FS T2 SSTSE Axial FS T2 SSTSE CorDiffusion AxialT2 Axial TSE FST1 Cor 3D GRE FST1 Axial 3D GRE (Dixon)T2 3D Cor NavSSH T2 Cor & Sag CineT1 3D COR GRE (Pre)Post ContrastT1 3D COR GRE (Arterial)T1 3D COR GRE (60 sec)T1 3D COR GRE (120 sec)T1 3D COR GRE (Delays)T1 3D GRE FS AxialT1 3D GRE FS CorT2 SSTSE Cor (Post Void)
9 Comprehensive MR Urogram Static-Fluid 2D/3D Urogram (T2)Independent of renal excretory, uses urine as contrast2D Cine SSH sequence allows visualization of moving urine3D sequences best with dilated/obstructed system.Excretory 3D Urogram (T1)Dependent of renal excretoryGood for non dilated system.Provides function and morphologyMRU/MRI/MRA provides a complete assessment of the Urinary SystemT2 3D Static Fluid2D Cine Static FluidT1 3D Excretory
10 MR UROGRAPHY Positioning Abd/Pelvis ScoutCoronal PositioningUretersCover from Above Kidneys to below Bladder for all AxialsCover entire Anatomy (Kidneys,Ureters ,and Bladder)
21 PREGNANCY Pregnancy (Acute): Contrast-enhanced MR urography is generally not recommended in pregnant women.3D T2-weighted (static-fluid) urography(Navigator) is performed.Cine MR urography(multiple acquisitions ) may be necessary to visualize the entire ureters and exclude fixed narrowing or filling defects.Images copyright of John R. Leyendecker, MD. Department of Radiology, Wake Forest University School of Medicine, Medical Center Blvd, Winston-Salem
22 PEDIATRICS Pediatric (Congenital): MR Urography provides imaging(Urinary System) without ionizing radiation.Is performed without iodinated contrast (Renal Impairment).Images copyright of John R. Leyendecker, MD. Department of Radiology, Wake Forest University School of Medicine, Medical Center Blvd, Winston-Salem
24 MR UROGRAPHY @ 3T Limitations: Dielectric Effect Minimized on newer scanners, dialectric pads.Susceptibility ArtifactsDue to local distortion(air, metal),use shortest TE available.Motion ArtifactsIncreases at 3T (Peristalsis, Flow)Specific Absorption Rate (SAR)HASTE, split the acquisitions in order to minimized SAR.Chemical Shift ArtifactsIncreases at 3T ,Steady State sequence are hampered by this artifact.
25 RENAL CALCULUS TRUFISP FS AXIAL T1 3D AX VIBE (Pre) T1 3D AXIAL VIBE (Post)
26 NEOPLASMRENAL CELL CARCINOMAAXIAL T1 3D VIBECORONAL T1 3D VIBE
28 POST PROCCESSING TECHNIQUES Maximum Intensity Projection (MIP) Volume Rendering (VR)Thin Volume (MIP)Multiple Planar Reconstruction (MPR)
29 PITFALLS & ARTIFACTS Non Dilated System (3D T2 Static Fluid) Pitfalls: Can mimic stricture/obstructionArtifacts:High concentration of GadoliniumT2* shortening (Single Dose)T2 COR HASTET1 3D VIBE POSTT2 3D Static Fluid
30 TIPS & TRICKS Prone Position Tips: Minimizes peristalsis motion CoverageInclude entire Urinary SystemAppropriate DelaysContinue scanning until ureters are fully filled.Full BladderImproves visualization of Urinary System.Prone PositionMinimizes peristalsis motionBetter visualization of Urinary system.Tricks:Use Navigator of Liver or Kidney (Nav within FOV)
31 CONCLUSION MR Urography: Is a technique that can be useful for assessing patients with a variety of urinary tract disorders.MRU provides a morphological and functional evaluation of the urinary system.Extremely useful on patients with no excretory function (T2).MRU can be combined with MRA/MRV and MRI of the urinary system to provide a complete diagnostic evaluation of the urinary system.