MR Cholangiopancreatography (MRCP) PROTOCOLS

MRCP PROTOCOL

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• Coronal SSFSE
• Axial T2 SE with respiratory triggering
• Axial T1 SPGR- spoiled gradient echo, in-phase with fat saturation of pancreas
• Coronal oblique SSFSE-RAO & LAO thin slice MRCP
• Coronal oblique SSFSE-RAO & LAOThick slab MRCP

MR Cholangiopancreatography (MRCP)

• An imaging technique that aims to replicate the information provided by endoscopic cholangiopancreatography (ERCP) and other cholangiographic techniques by developing very high contrast between fluid (in the ductal anatomy) and background tissues.
• Best results with extremely T2 weighted long ETL TSE sequences with fat suppression, acquired in a single breath hold.
• Slices < 4 mm can be processed in a MIP programme to allow some variation of projection
• Thick slices can provide very fast sequences with a single view and high in-plane resolution

MRCP Parameters  

Thick Slice

Localiser or simple display of ductal anatomy: 

Fat saturated single shot HASTE Axial and oblique coronal planes 

TR 2800 TE 1100 ETL 128 Slice thickness 70 mm FOV 300 mm Matrix 256 x 240 Resolution 1.27 x 1.2 mm Acquisition time 7 seconds ( uses 2 TR to establish steady state) 

Thin Slice 

For detailed depiction of gallstones or ductal obstruction 

Fat suppressed single shot HASTE Coronal 

TR 11.9 (infinite) Te 95 ETL 128 13 slices 4 m thick FOV 270 mm (7/8) matrix 256 x 240 resolution 1.13 x 1.05 mm Acquisition time 20 seconds

ANOTHER PROTOCOL Locator SSFSE Axial T2 Axial in-phase MRCP (Thin Slice) MRCP  (Thick Slab) ·        Schedule for 30 minutes slot in AM , preferably \before 11am ·        Patient must be npo after midnight, may drink water only prior to MRI.  This is important for making sure the gallbladder is distended. Patient Preparation: ·        Oxygen, 2-4 liters/min by nasal canulae is useful if patient is short of breath ·        Valium (5-10mg po) or Xanax (1-2 mg po) if patient is claustrophobic Series 1: Locator SSFSE shows the abdominal anatomy well.  It is done preferably with a breathhold in expiration so it can be used for planning Series 2 and 3 Axial T2 and T1.  It can also be performed without breath holding.  Alternatively, a breath hold FMPSPGR or coronal T1 spin echo (with respiratory compensation)  sequences are also adequate.   With SSFSE or FMPSPGR, use a sufficiently large FOV (ie. set FOV to width of patient) to eliminate wrap-around artifact. Series 2: Axial T2             This sequence identifies hepatic, pancreatic and other lesions.  It shows the common bile duct to guide acquisition of coronal oblique MRCP sequences.  If the respiratory waveform shows the pattern is breathing at regular intervalsàuse respiratory triggering.  If the breathing pattern is not regular then use fat saturation and 3-4 NEX.  Adjust slice thickness as necessary to cover liver and pancreas in 19-20 slice so the sequence will fit on a single sheet of film. Series 3: Axial in-phase (fat saturation)             This sequence is excellent for evaluating pancreatic pathology and especially for identifying pancreatic masses. Cover the entire pancreas.  If necessary, the slice can be made thicker if more coverage is needed. It must be performed with breath holding.  If the patient can not suspend breathing long enough, consider T1 spin echo (6 mm thick slice interleaved) with fat saturation. Series 4: MRCP (Thin Slice)             The purpose of this sequence is to comprehensively image the biliary system in patients suspected of biliary obstruction, stones or post liver transplantaion. It may be acceptable to perform just on straight coronal acquisition. But a more comprehensive study includes both oblique acquisitions. ·        Prescribe this series from the axial T2 series. Select an image which shows the common bile duct (CBD). ·        Use 5 mm thick with 0 gap slices ·        15 slices takes about 30 seconds, which is reasonable breath hold. Although breath holding is not essential, it does make reformations possible Coronal View:  Set the imaging volume from posterior to the CBD as it passes through the head of the pancreas to anterior to the parta hepatis. Ideally the entire gallbladder should be included within the 15 slices, but if it extends too far anteriorly, you may have to exclude part of the gallbladder in order to image the entire CBD. RAO:  Rotate 20-30 counterclockwise and include the CBD. Do not worry about excluding part of gallbladder. LAO:  Rotate 20-30 clockwise centered on the CBD and be sure to include entire gallbladder. Axial:  Set the axial plane at 4-5 mm slice thickness is useful in patients with suspected of pancreatic divisum. Series 5:  MRCP (Thick Slib)             This alternative approach to MRCP acquires an image of the entire biliary system in just 2 seconds.  Use oblique prescription and hold shift key down to prescribe multiple slabs at different angles.