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Focal liver lesions
MR imaging
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MRI TechniquesSequences
Coronal ultrafast spin-echo sequence(single breath-hold).
Axial fast spin-echo (T2-weighted)images.
Fat-saturated (frequency selective)
images increase the conspicuity ofliver lesions.
Axial 2D dual spoiled gradient-
recalled echo sequence (SPGR) (bothout-of- hase and in hase ima in
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Sequences
T1-weighted imaging
Diffusion-weighted imaging.
Dynamic contrast materialenhancedimaging at 20 (arterial phase), 60(portal venous phase), and 120
(equilibrium phase) seconds after theinjection of Gd-BOPTA and again at 1hour after injection
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Contrast agents
Extracellular fluid agents.
Hepatobiliary-specific agents.
Combined agents. Reticuloendothelial agents,
Blood-pool agents
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Hepatobiliary-specific Agents(Gd-BOPTA)
These hepatobiliary-specific agentsare taken up to varying degrees byfunctioning hepatocytes and are
excreted in the bile.
Gadolinium-based hepatobiliary-specific agents initially distribute in
the extracellular fluid compartment,just as extracellular fluid agents do,and are subsequently taken up by
hepatocytes.
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Focal liver lesions in MRI
Classification based on vascularizationpatterns
1.
Hypervascular lesions.2. Hypovascular lesions.
3. Lesions presenting delayed
persistent enhancement.
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Hypervascular lesions
Characterized by strong contrastenhancement in the arterial phasescan.
May be sharply demarcated or morediffuse appearance.
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Hemangioma
well-circumscribed mass of blood-filled spaces lined by endothelium ona thin fibrous stroma.
On T2-weighted images, they aremarkedly hyperintense and havecystlike signal intensity.
On T1-weighted images, hypointenserelative to the liver.
Three distinct enhancement patterns:
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Capillary Hemangioma
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Focal Nodular Hyperplasia
Represent a hyperplastic response ofthe hepatic parenchyma to apreexisting arterial malformation.
After hemangiomas, most incidentalhypervascular liver lesions innoncirrhotic livers represent FNH and
not adenoma. FNH - margin of the lesion, is
typically ill-defined or lobulated.
Adenomas - mar in is usuall smooth
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T1-weighted images - isointenserelative to the liver
T2-weighted images - isointense toslightly hyperintense.
Central scar is T1 hypointense and
T2 hyperintense.
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Hepatic Adenoma
Hepatic adenoma is a very rarebenign neoplasm.
Multiple in about 20% of cases,especially in patients with glycogenstorage disease.
Composed of benign hepatocytesthat are arranged in large plates orcords without acinar architecture.
T1-weighted images - variable signalintensit .
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Hepatic adenoma
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HepatocellularCarcinoma
Cirrhotic nodules range frombenign regenerative topremalignant dysplastic and frankly
malignant HCC. T1-weighted MR imaging, HCC
lesions less than 1.5 cm are often
isointense, whereas larger lesionsmay be hyperintense secondary tolipid, copper, or glycogen.
Fatty metamorphosis in a cirrhotic
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HepatocellularCarcinoma
In cirrhotic patients, a hypervascularmass with increased T2 signal similarto that of the spleen is suspicious for
HCC. DWI - Well-differentiated tumors are
often isointense, whereas moderately
to poorly differentiated tumors aremore often hyperintense.
Arterial phase -heterogeneous
enhancement, portal venous and
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HepatocellularCarcinoma
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HypervascularMetastases
Hypovascular metastases showdecreased enhancement relative tonormal liver and are most
conspicuous on portal venous phaseimages.
Hypervascular metastases enhance
earlier, are best seen on arterialphase images, and show washout ondelayed images.
These metastases typically arise
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Hypervascular lesions -arterial phase
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Hypervascular lesions -arterial phase
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Hypovascular lesions
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Delayed persistentenhancement
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