Liver Protocol (6/27/2008 updated)
Liver MR imaging may be helpful in detecting and diagnosing lesions especially when other radiological studies are inconclusive. Small tumors and hepatic masses in a diffusely fatty liver may not be easily discerned on CT or US. In such cases, MR imaging may be the modality of choice. Indications include but are not limited to evaluation of parenchymal disease such as cirrhosis and hemosiderosis, characterization of suspected benign lesions such as hemangioma, FNH, and adenoma, and demonstration of dysplastic nodules or HCC in the cirrhotic liver. Donor liver volume and vascular anatomy prior to liver transplantation can be reliably demonstrated with 3D MR Angiography an optimally timed contrast-enhanced dynamic 3D gradient echo study (see reimbursable ICD9 codes).
Scheduling Guidelines
· First Ask:
1.
Why is the liver MRI being requested?..................
2.
What prior liver imaging (CT, US) has been done?
…………..If prior imaging was performed in another imaging
center, please ask for a copy of report and ask patient to bring in films if
possible.
3. Have you had prior liver or gallbladder surgery? ………..…….. What operation? ………………
4. Have you ever had cancer? ……….. What type of cancer? ………….…… When was the cancer diagnosed? ……………….
5. Have you ever been diagnosed with any liver disease, such as hepatitis or cirrhosis? .............................
6.
What is the alpha fetoprotein level?
……LDH: ……SGPT: ….. SGOT: …… Alkaline Phosphatase: ……Total Bilirubin:
……
Patient Preparation
· Start intravenous line (20 or 22 gauge IV). If iv caliber is small (i.e. 22 gauge) then warm the Gd contrast up to body temperature to reduce its viscosity.
· Valium (5-10mg po) or Xanax (1-2 mg po) if patient is claustrophobic
· Ear plugs
Coil: 8 channel body coil
Patient positioning: Supine, feet first. The arms are positioned comfortably next to abdomen. Patient must have comfortable pillow for head and a cushion under the knees to relieve back pressure.
Landmark: Three fingers below the xyphoid at rib cage margin.
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Axl LAVA 90
MIN (optional)
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Coil
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8Cardiac
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8Cardiac
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8Cardiac
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8Cardiac
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8Cardiac
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8Cardiac
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8Cardiac
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IMAGING
PARAMETERS
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Plane |
3-Plane |
Axial |
Coronal |
Axial |
Axial |
Axial |
Axial |
Axial |
Coronal |
Axial |
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Mode |
2D |
Calib |
2D |
2D |
2D |
2D |
2D |
3D |
3D |
3D |
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Pulse Sequence |
Spin-Echo |
Fast GRE |
Spin Echo |
Spin Echo |
FRFSE-XL |
SPGR |
SPGR |
LAVA |
LAVA |
LAVA |
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Imaging Options
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Seq, Fast, SS |
Calib,Fast |
Fast, ZIP512, SS |
Fast, ZIP512, SS |
FC,TRF,Fast, ZIP512,FR |
EDR, Fast, ZIP512 |
EDR, Fast, ZIP512 |
EDR,Fast, ZIP512 |
EDR,Fast,
ZIP512,ZIP2
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EDR,Fast, ZIP2 |
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SCAN
TIMING
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# of TE |
1 |
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1 |
1 |
1 |
1 |
1 |
1 |
1 |
1 |
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TE |
102 |
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180 |
90 |
100 |
In phase |
Out of phase |
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TR |
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Minimum |
Minimum |
2110.0 |
200.0 |
200.0 |
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Flip Angle |
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90 |
90 |
12 |
12 |
12 |
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Bandwidth |
83 kHz |
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31.25 |
31.25 |
31.25 |
31.25 |
31.25 |
62.50 |
62.50 |
62.50 |
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ETL |
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17 |
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BSP TI |
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Prep Time |
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ADDITIONAL
PARAMETERS (see attached instructions)
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SAT |
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F:sp |
F:sp |
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Multiphase
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4-phases, Mask phase, pause after mask, auto subtract |
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ACQUISITION
TIMING
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Freq |
256 |
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256 |
256 |
256 |
256
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256 |
320 |
320 |
320 |
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Phase |
128 |
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192-256 |
192 |
160 |
160 |
160 |
192 |
192 |
192 |
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NEX |
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1 |
1 |
1 |
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Phase FOV |
1.00 |
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1 |
1.00 |
0.75 |
0.75 |
0.75 |
0.80
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0.80
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0.80 |
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# locs Bef Pause |
0 |
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10 |
0 |
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0 |
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0 |
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Freq DIR |
unswap |
R/L |
S/I |
R/L |
R/L |
R/L |
R/L |
R/L |
S/I |
R/L |
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Auto Cent Freq |
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Shim |
Auto |
Auto |
Auto |
Auto |
Auto |
Auto
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Auto |
Auto
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Auto |
Auto |
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Phase Correct |
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Yes |
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Yes |
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Contrast |
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No |
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SCANNING
RANGE
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FOV |
48 |
48 |
44 |
32.0 |
40 |
38 |
38 |
36 |
36 |
36 |
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Slice Thickness |
10 |
13 |
8 |
8 |
8 |
8.0 |
8.0 |
6 |
6 |
6.0 |
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Spacing |
5 |
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0 |
2.0 |
1.0 |
2.0 |
2.0 |
# of scan locs = 32 |
# of scan locs = 32 |
# of scan locs = 32 |
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Start - End |
Center = 0 |
I300-S300 |
A80-P70 |
0 |
0 |
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# Slices |
9/plane |
48 |
20 |
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Locs per slab |
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Scan Time |
0:22 |
0:13 |
0:29 |
0:00.74 |
0:21 |
0:26 |
0:26 |
5:09 (0:23) |
0:23 |
0:23 |
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This is a quick
localizer sequence obtained in three planes which is used to confirm optimal
patient positioning.
Array spatial
sensitivity encoding technique (ASSET) is a parallel imaging technique which
uses independent signals from each of the coil elements to accelerate data
acquisition. Prior to image acquisition with ASSET, a single breath-hold low-resolution
reference scan (ASSET calibration) must be run to obtain a sensitivity map for
each coil in the phased array for calculating the missing k-space data. These
sensitivity maps are needed to unwrap the aliasing in
the ASSET scan. ASSET calibration FOV is set to 48 cm and should be prescribed
from the top of the coil to the bottom of the coil.
Series 3: Coronal SSFSE
(single-shot fast spin-echo)
·
This sequence is
ready to go. If you do not want to run 3-plane localizer, and ASSET
calibration, just hit the “scan” button.
·
This sequence is
performed in inspiration as a guide for prescribing breath hold scans. In
really large patients (large in the AP dimension), it may be useful to cover
more anteriorly. When acquiring the coronal scan, use
the 8 channel body coil full FOV.
·
SSFSE sequence has some advantages over other T2
weighted imaging techniques; high SNR due to the reduced noise from ghost
artifacts, less respiratory motion artifact, and higher patient cooperation
compared to the long acquisition techniques. High CNR increases the lesion
detection especially for non-solid lesions.
· In SSFSE, a single 90° excitation pulse is followed by sufficient 180° pulses and readouts to encode half of k-space. This sequence is very RF intensive; to avoid from exceeding the specific absorption rate (SAR) limits, a refocusing flip angle of 130° may be preferred especially at 3T rather than the usual value of 180°.
· Slice acquisition order can be either interleaved or sequential. If you do not select sequential order, the interleaved technique is used. When sequential is used, the SNR and image contrast can decrease due to cross talk.
· Scan from top of liver to bottom of liver with breath hold (if possible).
· User CV: Fractional NEX optimization: if it is “on”, SNR and T2 weighting increase. If it is “off” the scan time is shorter.
· Maximum number of echoes is set to 260 (largest possible value). This improves image quality (SNR) at the expense of time.
· If you increase the bandwidth, image blurring may be decreased at the expense of SNR.
· Switch 8 channel body array coil to “upper”.
Series 5: Axial dual in-phase
and out-of phase
The purpose of using dual-phase
chemical-shift imaging is to detect lipid either in hepatic parenchyma or
within hepatocellular neoplasms.
This is a non-enhanced breath-hold T1-weighted spoiled gradient-echo
(SPGR) sequence in which periodic chemically selective fat-saturation pulses
have been incorporated. Short TRs and short TEs are used. When TE is in phase (4.2 ms at 1.5 T),
fat and water signals combine (in-phase imaging). Out-of-phase imaging
is performed with a TE of 2.1 ms at 1.5 T. Fat will lose signal
intensity on out-of phase images, because the signals from fat and water
protons cancel each other. This sequence is also helpful to look for iron
deposition in liver parenchyma. In patients with iron accumulation, parenchymal signal is lower on the longer TE in-phase
images.
· Select 2 echoes, system automatically acquires in and out-of-phase images.
· User CV: Select turbo mode before entering the matrix values. Turbo mode reduces the RF pulse width and therefore shortens the TR. As the turbo mode gets faster, tissue contrast decreases but vessel-background contrast increases.
· Scan from top of liver to bottom of liver. Breath-holding is critical. Repeat as necessary for optimum image quality.
Series 6: Axial 3D Dynamic Gd (FAME)
On older scanners this was performed as
out-of-phase 2D FMPSPGR with fat saturation to eliminate artifact at fat-organ
boundaries. On state-of-art scanners, 3D provides higher resolution and allows
zero filling (ZIP2) for overlapping reconstruction of slices. Repeat the scan
multiple times with breath holding as follows:
· Pre-contrast fat-saturated 3D volume images are obtained. These provide T1-weighted information.
· Begin to administer 0.1-0.2 mmol/kg dose of Gd contrast (typically 30 ml) at a rate of 3 ml/s, and set the fluoro-triggering to detect to contrast arrival. Operator may visually follow the contrast travel through the right heart, pulmonary arteries, ascending aorta and finally descending aorta. Triggering the scan should be done when the contrast arrives to proximal segment of abdominal aorta (diaphragmatic level). As soon as the operator observes the contrast arrival, instructs the patient to hold his/her breath at the end of inspiration, and triggers the sequence. There is a 5 s delay between triggering and the beginning of actual acquisition for breathe holding instructions.
· Gd injection is followed by 20 ml of saline flush at a rate of 3 ml/s.
· The first acquisition is timed for arterial enhancement. Same acquisition is performed subsequently multiple times in quick succession (10 seconds between each to allow patients to catch their breath) to acquire the portal, hepatic venous, and equilibrium phases. The scan may be repeated as much as desired. Delayed phase imaging: If the liver is cirrhotic, a delay of 3 minutes is adequate. If there is a suspicious lesion that might be hemangioma or cholangiocarcinoma, then repeat scan every 2-3 minutes out to 10 minutes. Cholangiocarcinoma is known to enhance late.
· A chemically selective fat-saturation pulse is applied just before each partitions loop. In the saturation pulse area, choose the ‘special’. The partitions loop is centric reordered to optimize fat-saturation uniformity.
· Zero-filling interpolation can reduce partial volume artifacts on 3D MR angiograms.
· The 3D volumetric imaging technique is a modified MRA sequence. The operator, by using “IVI” option and MIP algorithms on the scanner or Windows Advantage work station can obtain reconstructions of the arterial territories.
Series 7: Post-Gd Coronal T1
The late phase
delayed 2D sequence is performed using fat saturation. This includes abdomen
and pelvis and should be performed with the coil set to full FOV.
This sequence is performed when the study is
ordered for liver donor. It produces excellent vascular motion suppression with
respiratory compensation (ROPE) which is especially useful in patients who
cannot breathe hold.
Billing Instructions
570 |
Acute and subacute necrosis of liver |
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571 |
Chronic liver disease and cirrhosis |
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571.0 |
Alcoholic fatty liver |
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571.2 |
Alcoholic cirrhosis of liver |
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571.3 |
Alcoholic liver damage, unspecified |
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571.4 |
Chronic hepatitis |
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571.5 |
Cirrhosis of liver without mention of alcohol |
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571.6 |
Biliary cirrhosis |
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571.8 |
Other chronic nonalcoholic liver disease |
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571.9 |
Unspecified chronic liver disease without mention of alcohol |
572 |
Liver abscess and sequelae of chronic liver disease |
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572.0 |
Abscess of liver |
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572.3 |
Portal hypertension |
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572.8 |
Other sequelae of chronic liver disease |
573 |
Other disorders of liver |
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573.0 |
Chronic passive congestion of the liver |
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573.1 |
Hepatitis in viral diseases classified elsewhere |
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573.2 |
Hepatitis in other infectious diseases classified elsewhere |
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573.3 |
Hepatitis, unspecified |
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573.4 |
Hepatic infarction |
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573.9 |
Unspecified disorder of liver |
155.0 |
Primary malign neoplasm |
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155.1 |
Malign neoplasm of intrahepatic bile ducts |
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155.2 |
Liver, not specified as primary or secondary |
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211.5 |
Benign neoplasm |
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228.0 |
Hemangioma |
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239 |
Unspecified |
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197.7 |
Metastasis |
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789 |
Hepatomegaly |
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751.6 |
Congenital anomalies of liver |
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V42.7 |
Transplanted Liver |
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V59.6 |
Liver Donor |
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195.2 |
Malignant Neoplasm of Abdomen |
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Normal Liver Dictation Template
Clinical Statement:
Technique: 1.5 Tesla, phased array, coronal and axial SSFSE, axial in-and out-of-phase spoiled gradient echo, 3D dynamic Gd-enhanced (FAME) and post-Gd fat suppressed coronal T1 sequences.
Findings:
Ascites: No ascites
Liver: The liver is normal in size, contour and has normal signal intensity on all sequences. No focal hepatic lesions are identified.
Portal Vein: Widely patent
Hepatic Veins: Widely patent
Biliary: No dilatation
Gall
Bladder:
Spleen:
Pancreas: Normal in size and contour, normal signal intensity on all sequences, no focal lesions are identified.
Adrenal
Glands: No masses identified
Right Kidney:
Left Kidney: Normal in size, contour, signal intensity. No pelvicaliceal dilatation, no masses.
Retroperitoneum: No adenopathy
Impression: Normal MR of liver; no lesion identified.
Liver Hemangioma Dictation
Technique: 1.5 T, phased array coil, coronal and axial SSFSE, axial dual echo SPGR, 3D dynamic Gd-enhanced (FAME) and post-Gd fat suppressed coronal T1 sequences.
Findings: A…. x…. cm lesion is identified in the …….. lobe of the liver (segment #). It is T1 dark, homogeneously T2 bright with smooth margins and enhances with Gd initially with peripheral puddling which gradually progresses to homogeneous enhancement which persist on delayed images. There is no lesion suspicious for metastasis or malignancy. The liver size, contour and signal intensity are normal. The portal vein and hepatic veins are widely patent. There is no biliary dilation.
The pancreas, spleen, adrenal glands and kidneys are normal. No retroperitoneal lymphadenopathy is identified.
Impression: ….. x …. cm hemangioma in …….. lobe (segment….) of liver; otherwise normal abdominal
MRI findings.