mrcp: technique and interpretation “10 rules in mrcp” lieven van hoe md phd olv hospital group...
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MRCP: technique and interpretation
“10 rules in MRCP”
Lieven Van Hoe MD PhDOLV Hospital Group Aalst -
[email protected] www.lievenvanhoe.com
Procedure Axial and coronal double echo HASTE
(5mm)NON-FATSAT
TE 60 TE 360
10% of your patients has focal liver lesions
Double echo HASTE: lesion characterizarion
SITE 60
SITE 300-400
cyst ++ / +++ as bright as CSF
hemangioma
+ / ++ not as bright as CSF
solid ± / + ± isointense
60 msec 360 msec
solid
hemangioma
Axial and coronal double echo HASTE (5mm)
• Thin-section MRCP
• Scout for breath-hold single-slice MRCP
Procedure
Single-slice MRCP - RARE sequence– slice thickness 3 cm, TE 1100– 3 sec / image– breath hold
= overview images
Procedure
Axial non-FATSAT turboFLASH T1= magic tool for detection of pancreatic cancer
and focal liver lesions
Liver whitePancreas white
Tumor dark
Procedure
Multiphase contrast-enhanced VIBE
• Problem-solving tool• Pancreatic lesions• Only if required
T
P
Rule N° 1
Never use MRCP without cross-sectional imaging
Man, 43-year, elevated liver enzymes, previously papillotomy for biliary stone disease. Stone?
Aerobilia
Always correlate with axial T2-weighted images !!
Air-fluid levelExtensive air may make MRCP nondiagnostic
Liver function abnormalities
Missed pancreatic carcinoma
Never perform MRCP without cross-sectional imaging
never, never, never
TFLASH: 700 msec/slice – HASTE: 400 msec / slice
Rule N° 2
Use dynamic (repetitive) MRCP
May 13, 200310hr:12min:15sec
May 13, 200310hr:12min:23sec
Temporal variability in shape of the sphincter of Oddi
It works !
Only possible with breath-hold single-slice MRCP
Rule N° 3
Use the correct slice thickness
Not 10 cm !
10cm 5cm
2cm 3cm
Rule N° 5
Be aware of biliary flow phenomena on axial images
Flow void in
common bile duct
Compare with single-slice MRCP
Believe single-slice MRCP if results are different
axial T2
Rule N° 6
Be aware of the pseudo-calculus sign
Pseudocalculus sign
30 sec later
Rule N° 7
Small stones not surrounded by fluid are invisible
Not included in slice
Not included in slice
Does the patient has stones in distal CBD ??
Normal size
Impacted stone
May be difficult diagnosis !No surrounding fluid
Repetitive imaging useful
Rule N° 8
Anticipate differences between MRCP and ERCP
images
MRCP:- imaging in the physiologic state
(no ductal distention)
- limitations in spatial resolution
• Low-grade stenoses can be missed• The length of stenoses can be overestimated (physiologic collapse)• Small polypoid ductal lesions can be missed
MRCP – ERCPThe same things look different !!
(distention)
Aberrant right posterior duct
Rule N° 9
For lesion characterization, use all information available (T1, T2,
MRCP, multiphase contrast-enhanced images)
Cirrhosis. Incidental finding.
The double duct sign can be caused by chronic pancreatitis with pseudomass. Refer to axial T1- and T2-weighted images for differentiation with carcinoma.
Rule N° 10
Be aware of susceptibility artifact
Watanabe et al. RadioGraphics 1999 19: 415-429
Susceptibility artifactair
metal
Thank you !!
The double duct sign can be caused by chronic pancreatitis with pseudomass. Refer to axial T1- and T2-weighted images for differentiation with carcinoma.
Rule N° 4
Be careful with MIP images
The patient recently underwent laparoscopic gallbladder surgery and now suffers from jaundice. Injury to CBD?
MIP
Projects 3D reality on 2D image
Pathology may be masked