KINESIOL 1Y03 Lecture 17: MRI of the biliary tree(1)
23 Jun 2018
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MRI of the biliary tree (MCRP)
MRCP makes use of the fact that bile is essentially water:
uses very strong T2-weighted sequences which are sensitive to water and suppress
surrounding tissue
uses Single Shot Fast Spin echo (SSFSE) which acquires images quickly hence escaping
motion artefact (respiration / peristalsis / pulsatility), however doesn’t have as good
resolution as spin echo
Technique:
1) Carry out thick single slices of 4cm and 7cm in size through bile ducts, plus size in a rotation
2) Carry out thin section 1.2mm slices coronally through the whole area
3) Thin sections reconstructed into projection images which can be rotated to provide a 360
degree impression
4) Accompany bile-only images with suitable parenchymal images : these are strongly T2-
weighted gradient echo images (fiesta), which are rapid to acquire hence reasonably
resistant to motion artefact
Structures visualised
In a normal MRCP you can visualise the gallbladder, cystic duct (often spiral-formed),
common bile duct, pancreatic duct, some small bowel and the CSF (centrally)
CBD should be no greater than 6mm!!
Duodenum is 12 inches or 25cm long
Portal vein formed posterior to the pancreas by the joining of the splenic vein and superior
mesenteric vein
Stones
Can ONLY be excluded when you refer back to raw data thin sections, as projection images
mask stones because of the reconstruction algorithm hence look at thin sections in all
studies
May be seen in coronal and axial parenchymal (fiesta) images
Causes of filling defects
1) Gallstones
2) Blood clots (e.g. stringy blood clot formed post-ERCP will form elgonated filling defect)
3) Cholangiocarcinoma
4) Fungal balls
5) Worms/flukes (common in Burma/Thailand, chronic infection hence chronic cholestasis will
increase risk of cholangiocarcinoma)
6) Gas – may be due to medical insufflation of air – this will FLOAT with susceptibility artefact
around it in the axial parenchymal view c.f. stones will sink in the axial view
An apparent filling defect may actually be due to very low insertion of the cystic duct which causes
hepatic and cystic ducts to lie side-by-side appearing as a filling defect
Sclerosing cholangitis
Shows as multiple dilatations and strictures throughout the whole biliary tree highly
abnormal
This includes small filling defects in the intrahepatic ducts, presumably due to stasis
Associated with UC, increased risk of cholangiocarcinoma and colitic spondylarthropathies
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
In a normal mrcp you can visualise the gallbladder, cystic duct (often spiral-formed), common bile duct, pancreatic duct, some small bowel and the csf (centrally) Duodenum is 12 inches or 25cm long. Portal vein formed posterior to the pancreas by the joining of the splenic vein and superior mesenteric vein. Can only be excluded when you refer back to raw data thin sections, as projection images mask stones because of the reconstruction algorithm hence look at thin sections in all studies. May be seen in coronal and axial parenchymal (fiesta) images. Imflamed neck of gallbladder may impinge on cbd obstruction of cbd morrizis syndrome. An apparent filling defect may actually be due to very low insertion of the cystic duct which causes hepatic and cystic ducts to lie side-by-side appearing as a filling defect. Shows as multiple dilatations and strictures throughout the whole biliary tree highly abnormal. This includes small filling defects in the intrahepatic ducts, presumably due to stasis.
