MR UROGRAPHYEDUARDO D CAMPUZANO

BS,RT(R,MR,CT)

MR UROGRAPHYMR UROGRAPHY• MR Urography (MRU)- Have the potential to provide a

comprehensive assessment of the urinary system, renal parenchyma, vascular structures, and surrounding tissues

OBJECTIVES

• INDICATIONS

• PREPARATIONS

• PROTOCOL

• FINDINGS

• PITFALLS

• SUMMARY

URINARY SYSTEM

Diagnostic modalities:

• IV Urogram• Renal Ultrasound• CT Urography• MR Urography

CT is the imaging of choice for acute symptoms

INDICATIONS

Clinical Indications:– Hematuria 

– Urolithiasis 

– Stricture/Obstructions

– Anomalies

– Neoplasm

– Renal Insufficiency/Allergy

– Pregnancy/Pediatrics

MR UROGRAPHY

Advantages over CT Urography:• Elimination of ionizing radiation• Non Ionic Contrast• Contrast Resolution• Non Contrast imaging (T2 Imaging)

Disadvantages vs. CT Urography:• Claustro/Implants• CT: 15 min vs. MR: 45 min• Spatial resolution ( 3-6 mm)• Calcifications not seen• Cost• Uncooperative patient

CT is the modality of choice for acute symptoms

PATIENT PREPARATION

• 250 ml IV normal saline solution– PO Water (30 minutes prior to MRI)

• Furosemiode/Lasik– Non Dilated Systems

• Glucagon– Minimized Peristalsis

• Intravenous Contrast (Multihance)– Single Dose

MR UROGRAPHY PROTOCOL

Pre Contrast

• T2* SSFP Axial FS• T2 SSTSE Axial FS• T2 SSTSE Cor• Diffusion Axial• T2 Axial TSE FS• T1 Cor 3D GRE FS• T1 Axial 3D GRE (Dixon)• T2 3D Cor Nav• SSH T2 Cor & Sag Cine• T1 3D COR GRE (Pre)

Post Contrast

• T1 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 Axial• T1 3D GRE FS Cor• T2 SSTSE Cor (Post Void)

Comprehensive MR Urogram

• Static-Fluid 2D/3D Urogram (T2)

• Independent of renal excretory, uses urine as contrast• 2D Cine SSH sequence allows visualization of moving urine• 3D sequences best with dilated/obstructed system.

• Excretory 3D Urogram (T1)

• Dependent of renal excretory• Good for non dilated system.• Provides function and morphology

T2 3D Static Fluid T1 3D Excretory2D Cine Static Fluid

• MRU/MRI/MRA provides a complete assessment of the Urinary System

MR UROGRAPHY Positioning

Abd/Pelvis Scout

Cover from Above Kidneys to below Bladder for all Axials

Coronal Positioning

Ureters

Cover entire Anatomy Cover entire Anatomy (Kidneys,Ureters ,and Bladder)(Kidneys,Ureters ,and Bladder)

MR UROGRAPHY Positioning

Axial T2 TSE Fat Sat Coronal Positioning

Ureters

Cover entire Anatomy Cover entire Anatomy (Kidneys,Ureters ,and Bladder)(Kidneys,Ureters ,and Bladder)

3D UROGRAMCoverage

• Increase coverage on the 3D volume (cost time)• Angle 3D volume to cover entire anatomy

(Kidneys,Ureters and Bladder)

3D T2 Static-Fluid

• Place Navigator Box, on your Coronal images.• Check box placement in the Axial images.

Maximum Intensity Projection (MIP)

Volume Rendering (VR)

SSH T2 Coronal Cine

• Same sequence as a Single Shot MRCP• Except only 1 slices in multiple measurements

SSH T2 Coronal Cine Positioning

Use 8-12 Dynamics(cine) Wait 5-10 secs between dynamics

2D Slab SSFSE ( Red Box) Sat Band (Yellow Box),angle if needed

1- Sagittal Scout SSH T2 (Cine) COR

SSH T2 Sagittal Cine Positioning

Use 8-12 Dynamics(cine) Wait 10 secs between dynamics

2D Slab SSFSE ( Red Box),70-80 cm Angle if needed ,do Both Kidneys.

1- Coronal SSH SSH T2 (Cine) Sag

SSH T2 Sagittal Cine Positioning

1- Coronal SSH SSH T2 (Cine) Sag

Ureter must be seen in cine, reposition/repeat if needed

STRICTURE/OBSTRUCTION

STRICTURE/OBSTRUCTION

T2 3D Static Fluid

2D Cor Cine Static Fluid

2D Sag Cine Static Fluid

KIDNEY TRANSPLANT

T2 Axial TSE3D Cor T2 Static Fluid

2D Cor Cine

PREGNANCY

• Pregnancy (Acute):

1.Contrast-enhanced MR urography is generally not recommended in pregnant women.2.3D T2-weighted (static-fluid) urography(Navigator) is performed.

3.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

PEDIATRICS

• Pediatric (Congenital):

1.MR Urography provides imaging(Urinary System) without ionizing radiation.2.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

MR UROGRAPHY AT 3T

MR UROGRAPHY @ 3T

Limitations:• Dielectric Effect

• Minimized on newer scanners, dialectric pads.• Susceptibility Artifacts

• Due to local distortion(air, metal),use shortest TE available.

• Motion Artifacts•Increases at 3T (Peristalsis, Flow)

• Specific Absorption Rate (SAR)•HASTE, split the acquisitions in order to minimized SAR.

• Chemical Shift Artifacts•Increases at 3T ,Steady State sequence are hampered by this artifact.

RENAL CALCULUS

TRUFISP FS AXIAL

T1 3D AXIAL VIBE (Post) T1 3D AX VIBE (Pre)

RENAL CELL CARCINOMA

NEOPLASM

CORONAL T1 3D VIBEAXIAL T1 3D VIBE

RELATED PATHOLOGIES

Gonadal Vein Varicose

Uterine Fibroids

Bladder Thickened Prostate Enlargement

Renal Cyst

TECHNIQUES

POST PROCCESSING

Maximum Intensity Projection (MIP)

Thin Volume (MIP)

Volume Rendering (VR)

Multiple Planar Reconstruction (MPR)

PITFALLS & ARTIFACTS

Pitfalls:• Non Dilated System (3D T2 Static Fluid)

• Can mimic stricture/obstruction

Artifacts:• High concentration of Gadolinium

•T2* shortening (Single Dose)

T2 3D Static Fluid

T1 3D VIBE POSTT2 COR HASTE

TIPS & TRICKS

Tips:• Coverage

• Include entire Urinary System

• Appropriate Delays

• Continue scanning until ureters are fully filled.• Full Bladder

• Improves visualization of Urinary System.

• Prone Position• Minimizes peristalsis motion• Better visualization of Urinary system.

Tricks:• Use Navigator of Liver or Kidney (Nav within FOV)

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.