Type:
Educational Exhibit
Keywords:
Education, CT, MR, Pancreas, Gastrointestinal tract, Biliary Tract / Gallbladder, Cholangiography, Artifacts, Calcifications / Calculi, MR-Cholangiography
Authors:
H. D. Peiris1, S. McGee2, D. Sheppard3, M. S. B. T. Wills3; 1Southampton/UK, 2Salisbury, Wiltshire/UK, 3Salisbury/UK
DOI:
10.1594/ecr2018/C-0610
Background
Technique
MRCP is a non-invasive imaging technique that is essential in investigating pancreaticobiliary disorders.
It relies on heavily T2 weighted pulse sequences to accentuate static fluid signal within structures such as the biliary tree which possess a long T2 relaxation time relative to surrounding soft tissues with shorter T2 relaxation times1.
As such,
these images provide relatively little anatomical detail.
A comprehensive protocol will include additional (more anatomical) sequences for correlation and to complete the assessment.
Intravenous contrast is not required and thus this technique can be used for patients with impaired renal function.
Modified fast spin echo (FSE) techniques such as HASTE are utilised,
along with isometric voxels in image acquisition,
to enable multiplanar reformats (MPR) and maximum intensity projection (MIP) images.
Pathology within the biliary tree manifests as areas of ‘signal void’ or ‘absent signal’,
as a gallstone or stricture result in loss of the normal fluid high-signal.
Artefacts
Inherent to any imaging technique would be artefacts that degrade image quality.
The more important artefacts are that of respiratory motion (i.e.
breathing artefact),
and post-surgical artefact (e.g.
cholecystectomy clips) which may lead to a false diagnosis (e.g.
the appearance of a biliary stricture due to signal loss from metallic susceptibility artefact),
or could be falsely reassuring.
Indications
Common indications for MRCP include the suspected diagnosis of choledocholithiasis,
stricturing disorders,
and delineating post-surgical anatomy or complications such as bile duct injury.
It additionally plays a role in evaluating rarer conditions including congenital anomalies such as pancreas divisum.
Pancreatic cystic neoplasms may also be evaluated using MRCP.