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Mri nephrology 2017 by mohamed abou el ghar
1. B Y
M O H A M E D A B O U E L - G H A R
U R O L O G Y & N E P H R O L O G Y C E N T E R
M A N S O U R A U N I V E R S I T Y
MRI of The kidney
2. What is MRI
MRI is a machine creates a magnetic field, sends
radio waves through your body, and then measures
the response with a computer.
This creates an image or picture of the inside of your
body that is much clearer than can be obtained with
most other methods.
3. MRI
The potential advantages of MRI for
evaluating urinary tract abnormalities are:
No ionizing radiation.
Multiplanar capabilities.
Excellent anatomic resolution and
soft tissue contrast.
4. Before MRI
Cardiac pacemaker or
implantable defibrillator.
Catheter that has metal
components.
Metallic prosthesis.
A ferromagnetic metal
vascular clip.
An implanted or external
medication pump.
A cochlear implant.
A neurostimulation system.
5. MRI EXAMINATION TECHNIQUES
• high magnetic field (1.5 – 3 Tesla)
• high performance gradients
• phased-array coil → high SNR & small FOV
12. 3D GRE sequence
HIGH SPATIAL RESOLUTION
HIGH TEMPORAL RESOLUTION
MRI EXAMINATION TECHNIQUES
• Single shot or multishot
• Full coverage of the kidney in one 18-23 s
breathhold
13. 3D GRE T1 SEQUENCE
+
GADOLINIUM
DYNAMIC CONTRAST-ENHANCED MR IMAGING
MRI EXAMINATION TECHNIQUES
18. MRU
MRU is the most important
technique in uroradiology.
It has a good diagnostic value in
virtually all kinds of urinary tract
disorders.
MRU can reduce the need for
radiation exposure and invasive
procedure.
20. T2-W(static –Fluid) MRU
In static- fluid MRU, Heavily T2w Turbo spin
echo (TSE) sequences are used to obtain
water images of the urinary tract.
It is used to image fluid filled cavities such as
hydronephrosis.
21. • slice thickness: 6-10 cm
• inclusion of the entire pelvicaliceal system and the
whole course of the ureters
• coronal plane and sagittal plane
SINGLE SLICE PROJECTION IMAGE
Advantages:
• acquisition time: 3-8 s
• no motion artifacts
• no post-processing
• ureterohydronephrosis and
location of obstruction
Disadvantages:
• no cause of obstruction
• low spatial resolution
• low signal to noise ratio
MRU EXAMINATION TECHNIQUES
22.
23. MULTISLICE TECHNIQUE
• overlapping slices
• section thickness: less than 5 mm
• post-processing: MIP images
Advantages
• reduced partial volume
averaging
• small pathological details
Disadvantages
• more time consuming
• superimposing extraurinary
fluid
MRU EXAMINATION TECHNIQUES
26. T1-w excretory MR Urography
Excretory MRU imitates the conventional
IVU.
Gd-Enhanced urine is imaged with use of fast
T1-w GRE sequences.
Low –molecular –weight Gd have
demonstrated a good safety profile at
standard clinical dose.
27.
28. Diffusion-weighted imaging (DWI)
• MR diffusion-weighted imaging (DWI) provides information on the
velocity and direction of movement of the water molecules in tissue
under influence of a diffusion gradient
• The velocity and direction of the diffusion movement of the water
molecules can be quantified by means of the apparent diffusion
coefficient (ADC)
Koh DM et al, AJR (2007)
MRI EXAMINATION TECHNIQUES
36. All In Approach
Preoperative assessment of potential live
kidney donor.
Basal study of transplanted kidney.
Pelviureteral junction obstruction.
Nephron sparing surgery.
37.
38.
39.
40.
41.
42. MR Urography
Obstructed or non-obstructed?
Urothelial lesions.
Cause of obstruction.
Congenital Anomalies.
47. Ectopic kidney
-Simple renal ectopy refers to a kidney that remains in the
ipsilateral retroperitoneal space.
-The most common position is in the pelvis or sacral
region below the aortic bifurcation.
-Crossed renal ectopia with fusion occurs in 85%, without
fusion in less than 10%.
ANOMALIES OF POSITION
50. In infancy the
appearance is variable,
from normal to few
isolated cysts, rarely a
kidney packed with
cysts.
There is preservation
of the renal shape,
echogenicity and
cortico -medullary
differentiation.
ADPCKD
51. ARPCKD
Kidneys: the dilated
tubules are responsible for
the appearance.
- Kidneys enlargment.
-Diffuse increase
echogenicity and
hyperechoic foci on US.
-Low attenuation with
striate pattern on CT.
-Diffuse increase signal
intensity in T2 w Images
on MRI.
-Macro cyst in varying
patterns can be present.
Liver: dilatation of the bile
ducts.
68. NSF
Nephrogenic systemic fibrosis (NSF) is a relatively
uncommon condition in which fibrous plaques
develop in the dermis and, often, in deeper
connective tissues.
Reported cases have occurred almost exclusively in
patients with severe renal disease, and almost all
have been associated with prior use of gadolinium-
containing MRI contrast agents.
The disease is often disabling, no proven treatments
exist.
69. Clinical features of NSF
Onset: From the day of exposure for up to 2–3 months
Initially
– Pain
– Pruritus
– Swelling
– Erythema
– Usually starts in the legs
Later
– Thickened skin and subcutaneous tissues — ‘woody’ texture and brawny
plaques
– Fibrosis of internal organs, e.g. muscle, diaphragm, heart, liver, lungs
Result
– Contractures
– Cachexia
– Death, in a proportion of patients
70. Who is at RISK
Whilst cases have occurred in patients with either
acute or chronic renal failure.
Most have been in patients with chronic and severe
kidney disease (CKD Stage 4 & 5, glomerular
filtration rate (GFR) < 30 ml/ min/1.73 m2); most
have been on dialysis.
At lower risk Patients with CKD 3 (GFR 30-
59ml/min)
Not at risk of NSF Patients with stable GFR > 60
ml/min
71. Take care
Children under one year of age, have a
physiologically low GFR yet no case of NSF has been
reported in a patient under the age of 6 years.
In lactating patients, the proportion entering the
breast milk is very small (1% of the injected dose),
and very little of this is actually absorbed. Hence the
risk to the child would appear negligible.
Lactating women: Stop breastfeeding for 24 hours
and discard the milk.
Pregnant women: Can be used to give essential
diagnostic information.
72. High Risk Patients
The minimum adequate dose of gadolinium is used.
Restrict dose to 0.1 mmol/kg and avoid repeat scans.
Consider immediate post-scan hemodialysis.
A single conventional hemodialysis session will
remove 75% of the free Gadolinium – a 2nd
treatment 93% and a 3rd treatment 98% of a dose.
If the patient has severe renal failure, but is not
receiving hemodialysis, the possibility of
commencing hemodialysis will need individual
consideration.
73. ESUR Guidelines, 8.1 Contrast Media
Guidelines
Never deny a patient a clinically well- indicated
enhanced MRI examination.
In all patients use the smallest amount of contrast
medium necessary for a diagnostic result.
