CT AND MRI UROGRAPHY

DR. DEV LAKHERA

UROGRAPHY DEFINITION

Urography is a radiologic technique used for the evaluation of the genitourinary system: specifically, the kidneys, ureters and bladder.

UROGRAPHIC TECHNIQUES

INTRAVENOUS UROGRAPHY

COMPUTERIZED TOMOGRAPHIC UROGRAPHY

MAGNETIC RESONANCE UROGRAPHY

CT urography

Hybrid CTU

CT Urography

Hybrid CT urography

CT and IVU are done together. Adv :- no reformatting needed Disadv:- Imaging at different

location

CTU Protocol –Three phase protocol

Unenhanced phase

Nephrographic phase after 90-100 secs

Pyelographic phase after 12-15 minutes

4 Phase protocol (5 min and 7.5 min)

Contrast media

Omnipaque (100-150 ml non ionic contrast media at a rate of 2-4 ml/second)

Split Bolus MDCT Urography with Synchronous Nephrographic and Excretory Phase Enhancement

Unenhanced Phase Nephro-pyelographic phase : 30 ml of nonionic

contrast material is infused and after 10 min another 100 ml of contrast is injected

ADV: Assess tract with low radiation exposure.

Image post processing techniques

Multiplanar Reformation (MPR)

Maximum Intensity Projection (MIP)

Projecting the voxel with the highest attenuation value on every view throughout the volume onto a 2D image

Volume rendering technique (VRT)

Indication of CT Urography

To evaluate patients with hematuria Calculi Renal / Urothelial tumors Congenital anomalies.

Renal calculi

Presence, size and location of

urinary tract calculi

Exclude extraurinary pathologies

that may mimic calculi

Renal Tumors

Enhancement : Nephrographic phase

Location : Renal cell carcinoma is frequently located at the periphery or near the cortico-medullary junction of the kidney as it originates in the renal cortex

tumors with nephron sparing surgery

CT urogram (volume rendering )

Axial CECT

UROTHELIAL CARCINOMA

Excretory phase CTU shows a soft-Tissue attenuation mass in upper left kidney with associated calyceal distortion

Coronal reformatted image MIPimage

Papillary necrosis

Ureteric injury

Congenital anomalies Retrocaval ureter Ureteral duplication Crossed fused kidneys Ectopic kidneys

Fused low lying ectopic kidney

Maximum intensity projection curved planar reformation excretory phase CT urogram

Advantages of IVU over CT urography

Better spatial resolution

Lesser radiation dose

Cheaper

Ct urography: Advantages Multidetector CT : Thin slices in single breath hold allow

optimal anatomic information

Isotropic MPR reconstruction

Better contrast resolution

Image improvement techniques

Compression Saline Infusion Diuretic Administration Patient Positioning

34 year old lady with pain Left side of abdomen, and hydronephrosis on USG

MR Urography

urinary tract obstruction Hematuria congenital anomalies surgically altered anatomy

beneficial in pediatric or pregnant patients or when ionizing radiation is to be avoided

Principle

urine have very long T2-relaxation time

heavily T2-weighted pulse sequence generate images with high signal

intensity from static fluid

Sequences Without contrast administration : Heavily T2-weighted

static-fluid MR urograms Half fourier acquisition single-shot turbo spin-echo(HASTE

sequence)

With contrast administration with excretory T1-weighted sequences (excretory MRU)

Static fluid MR Urogram

demonstrates the collecting system, ureters and bladder

Coronal static-fluid MR urogram shows obstruction of the right distal ureter in a patient with prostrate cancer

Coronal single-shot fast spin-echo image shows a metastatic lymph node

Excretory urography

Gadolinium shortens the T1 relaxation time of the urine, allowing the urine to initially appear bright on T1-weighted image

Dose: 0.1 mmol/kg

Effect of gadolinium excretion on T2-weighted MR urographic techniques

static-fluid MR urography MIP excretory urography after gadolinium

Advantages

MRU has better contrast resolution than CT urography

without radiation exposure and IV contrast administration

Disadvantages over CT Urography

Longer examination times than for CT urography

Decreased spatial resolution

Inability to reliably depict calcifications and calculi

THANK YOU