Mesenteric-Portal Protocol
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IMAGING
PARAMETERS |
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Plane |
Sagittal |
Axial |
Axial |
Coronal |
Coronal |
Axial |
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Mode |
2D |
2D |
2D |
2D |
3D |
2D |
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Pulse Seq |
Spin Echo |
Spin Echo |
SPGR |
Spin Echo |
Spin Echo |
Spin Echo |
Vasc, TOF, SPGR |
Gradient Echo |
|
Imaging Options |
RC |
SS, Fast |
Fast |
RC, NPW |
FC, Fast |
Seq, Fast, SS |
Fast, MPh, ZIP´2, SmartPrep |
RC, FC, NPW, Seq |
|
SCAN
TIMING |
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|
# of Echoes |
1 |
1 |
1 |
1 |
1 ETL=8 |
1 |
1 |
1 |
|
TE |
Min Full |
90 |
Min Full |
Min Full |
112 |
180 |
Minimum |
Min Full |
|
TR |
275 |
-- |
160 |
300 |
3200 (2K-6K) |
-- |
-- |
2 |
|
Flip Angle |
-- |
-- |
60 |
-- |
-- |
-- |
45 |
60 |
|
Bandwidth |
-- |
31.25 |
31.25 |
-- |
-- |
31.25 |
31.25 |
15.63 |
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ADDITIONAL
PARAMETERS (see attached instructions) |
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SAT |
None |
None |
None |
S, I |
S, I, FAT |
FAT |
None |
None |
|
ACQUISITION
TIMING |
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|
Freq |
256 |
256 |
256 |
256 |
256 |
256 |
256 |
256 |
|
Phase |
256 |
256 |
160 |
256 |
192 (192-256) |
256 |
160 (128-192) |
256 |
|
NEX |
2 |
-- |
-- |
2 |
4 |
-- |
0.5 (0.5-1) |
4 |
|
Phase FOV |
1 (0.75-1) |
1 (0.75-1) |
1 (0.75-1) |
-- |
1 (0.75-1) |
1 |
1 |
-- |
|
Locs Before Pause |
-- |
0 (0-5) |
-- |
-- |
0 |
0 (0, 5, 10) |
1 |
-- |
|
Freq DIR |
S/I |
S/I |
S/I |
R/L |
R/L |
S/I |
S/I |
R/L |
|
Auto Center Freq |
Fat |
Water |
Fat |
Peak |
Water |
Water |
Water |
Water |
|
Auto Shim |
on |
on |
on |
on |
on |
on |
on |
off |
|
Contrast |
-- |
-- |
-- |
-- |
-- |
-- |
42ml |
42ml |
|
SCANNING
RANGE |
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|
FOV |
40 (36-48) |
40 (36-48) |
40 (36-48) |
34 |
34 (28-40) |
34 (28-40) |
34 (28-44) |
32 |
|
Slice Thickness |
10 |
8 |
8 |
10 |
8 (8-12) |
5 |
3 (2.6-4) |
8 |
|
Spacing |
Interleave |
0 |
1 |
Interleave |
2 (2-3) |
0 |
-- |
0 |
|
Start - End |
L95-R95 |
L70-R80 |
L70-R90 |
-- |
-- |
-- |
-- |
-- |
|
# Slices |
20 |
20 |
20 |
9/Acq. |
20 |
42 |
40 (30-50) |
20 |
|
|
|
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Scan Time |
5:07 |
0:43 |
0:27 |
3:00/Acq. |
5:14 |
0:02/Slice |
1:27 |
8:18 |
Common Indications:
- Abdominal
pain (especially post-prandial)
- Weight
loss
- Pre-op
mapping of mesenteric arterial anatomy
- Post-op
check
- Pre-liver
transplant
- Post
liver transplant
- Start
intravenous line (20 or 22 gauge iv). If iv caliber is small (i.e. 22
gauge) then pre-warm the gadolinium contrast to body temperature to reduce
its viscosity.
- Oxygen,
2-4 liters/min by nasal canulae is essential if patient is short of
breath.
- Valium
(5-10mg po) or Xanax (1-2 mg po) if patient is claustrophobic can be
given.
Coil: Body coil has a large field-of-view and uniform sensitivity. The torso
array has higher SNR, consider rotating 90 degrees for greater S/I coverage.
Patient Positioning: Supine, feet first,
Landmark: Just below tip of xyphoid
SSFSE (series 1B) is the preferred sequence
because it is fast, does not require breath holding, shows the abdominal
anatomy well and provides an extra T2 weighted view of the liver parenchyma as
well as a view of the gallbladder and main bile ducts. However this sequence is
only available on high performance echo-planar magnets. Accordingly, the
spin-echo black blood sequence (series 1A) can be performed also without requiring
breath holding although it is essential to use respiratory compensation. A
faster breath hold FMPSPGR (series 1C) is also provided. This is preferred in
the patients with profound ascites where the spin echo localizer does not work
well due to rf attenuation by ascites.
The purpose of this sequence is to evaluate
the retroperitoneal anatomy especially for adenopathy or other masses. It
outlines the shape of the liver to identify features typical of cirrhosis or
which are typically found with portal hypertension (i.e. varices,
splenomegaly).
- Scan
entire liver from dome to tip of right lobe and try to include kidneys as
well.
- Since
it is an interleaved acquisition, be sure to check the first set of images
which are reconstructed halfway through the acquisition to be sure it is
working properly.
Series 3: Axial T2 with fat
saturation
The purpose of this sequence is to identify
and evaluate any liver or renal masses or cysts that might be present. It also
provides a black blood evaluation of the portal vein and can help identify
inflammatory processes that can precipitate portal vein thrombosis.
If the patient breathes regularly, better
quality is possible by using respiratory trigger. When using respiratory
trigger the TR is determined by the respiratory rate. Thus the slice thickness
and gap must be adjusted to cover the liver with the number of slices possible
at the patient’s respiratory rate. It may be necessary to increase slice
thickness up to 12 mm and the gap up to 3 mm in order to cover the liver
without having to use 2 acquisitions.
|
The purpose of this sequence is to
comprehensively image the biliary system in patients suspected of biliary
obstruction, stones or post liver transplantation. It may be acceptable to
perform just one straight coronal acquisition. But a more comprehensive study
includes both oblique acquisitions.
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MRCP |
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- Coronal
View: Set the imaging volume from posterior to the CBD as it passes
through the head of the pancreas to anterior to the porta 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
Use at least 0.3 mMol/kg, usually 2 or 3
bottles (20ml/bottle).
- ADDITIONAL PARAMETERS
- Vascular Screen:
- Projection Images: 0
- Collapse: on
- User CVs Screen:
- Max. Monitor Period: 35
- Image Acq. Delay: 8
- SPECIAL: off
- Multi Phase Screen:
- Phases per Location: 3
- Delay After Acq: minimum (550)
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- To
determine where to position the 3D Volume, first find the celiac and SMA,
the right and left kidneys and the portal vein. The portal vein is between
the celiac and SMA and on axial images it can be seen in the porta
hepatis.
- Scanning
range
- Posterior:
mid-kidney
- Anterior:
4-5 cm. anterior to the portal vein bifurcation and pancreas.
- If
you cannot find the portal vein, use thick slices (up to 4 or 5 mm thick)
and scan to within 2 cm of the anterior edge of the liver.
- Make
sure the acquisition time is short enough so that the patient can suspend
breathing for the entire scan, twice in a row (once for the arterial phase
and again for the venous phase). To make the scan time shorter consider
- Decreasing NEX to 0.5
- Decreasing matrix to 128
- Decreasing number of slices and increasing slice
thickness
- Covering only the essential anatomy
- Use
"fallback" for optimal right-left alignment
- Check
"#of Locs Before Pause" to be sure it is set to 1.
- Place
the patient’s arms over the head or on cushions to get them out from along
side the patient where they will wrap around into the imaging volume.
Test the iv with saline and then fill the iv
tubing (SmartSet) with Gd contrast (about 7 ml). - Instruct
the patient on when to suspend breathing: "This is the most important
scan. You will need to hold your breath for 1/2 of the scan, the second
half. You can tell when to hold your breath by the change in the sound.
Just to be sure there is no confusion, I will squeeze your arm when the
sound changes so that you will know exactly when to take in a deep breath
and hold it."
- Start
scan: Do not begin injecting until the clock begins to count down: about
15 seconds after starting the scan.
- When
the clock begins counting down, starting injecting at about 1-2 cc/sec (as
fast as you can, for a person of average strength using Magnevist with a
20 gauge iv).
- When
the sound changes (bolus detected), signal the patient to Breath Hold by
squeezing arm.
- When
Gd infusion is complete, flush with 20 cc normal saline.
At the end of the arterial phase scan, have
the patient take 3-4 quick breaths and then scan again to catch the portal
venous phase. Then allow the patient to breath several times until relaxed and
breath hold for one final scan during the equilibrium phase.
Series 6:
Axial 2D TOF Post Gadolinium (Optional)
- This
sequence provides an additional view of the IVC, hepatic vein and portal
vein with high SNR without requiring breath holding. Using respiratory
compensation eliminates respiratory motion. It also provides a
post-gadolinium evaluation of any lesions seen in the liver. Use 5 mm
thick slices.
- Scan
from dome of the liver to tip of right lobe.
- Use
at least 4NEX with 256 phase encoding steps for maximum signal averaging.
Series 7: Axial 3D Phase Contrast
(Optional)
From renal MRA protocol in patients who also
are suspected of renal artery stenosis.
- ADDITIONAL PARAMETERS
- Vascular Screen:
- Projection Images: 0
- Flow Recon Type: Phase Diff.
- Velocity Encoding: 40 (20-50)
- Acq. Flow Direction: ALL
- Collapse: on
- Flow Analysis: off
- Additional Flow Images: none
- See
Renal MRA protocol for discussion of Venc selection and volume positioning
Billing:
- MRI of Abdomen 74181
- MRA of Abdomen 74185
- Computer Reconstructions 76375
ICD9 Codes:
|
441.00 |
Dissecting aneurysm of
aorta, unspecified site |
|
441.02 |
Dissecting of aorta
(ruptured), abdominal |
|
441.03 |
Disssecting aneurysm of
aorta (ruptured), thoracoabdominal |
|
441.4 |
Abdominal aneurysm, without
mention of rupture |
|
441.7 |
Thoracoabdominal aneurysm,
without mention of rupture |
|
441.9 |
Aortic aneurysm of
unspecified site without mention of rupture |
|
442.1 |
Otheraneurysm of renal
artery |
|
442.2 |
Other aneurysm of iliac
artery |
|
442.83 |
Aneurysm of splenic artery |
|
442.84 |
Aneurysm of other visceral
artery |
|
444.0 |
Arterial embolism and
thrombosis of abdominal aorta |
|
444.81 |
Arterial embolism and
thrombosis of iliac artery |
Sample Normal Dictation:
The patient's abdomen was imaged with Sagittal
SSFSE, Axial T2, Axial T1, Coronal SSFSE, coronal 3D dynamic Gd:MRA during
arterial and venous phases and axial 2D TOF post gadolinium. MRA image data was
post-processed on a computer workstation to obtain reformations and MIPs
optimized for each of the major vessels.]
The abdominal aorta has normal caliber and contour. The celiac, SMA and IMA
origins are all widely patent. The SMV, splenic vein portal vein and hepatic
veins are all widely patent. No varices are identified. Bowel enhances normally
with no areas of delayed enhancement to suggest ischemia identified.
The liver, spleen, kidneys pancreas and adrenal glands all have normal signal
and morphology; no masses are identified. There is no retroperitoneal
adenopathy.
Impression: Normal abdominal MRA; no evidence of mesenteric ischemia or portal
vein thrombosis.