Role of MRI in liver imaging
• Suspected Liver Metastases
– CT is the imaging modality of choice
– Diffuse liver disease and fatty infiltration limit the
sensitivity of CT in lesion detection. If the clinical
suspicion of a lesion is high and the CT scan is
• Preoperative Evaluation of Liver Tumors
– Contrast-enhanced MRI is superior to CT - high
sensitivity for detecting small lesions and its ability to
characterize small lesions.
– Tissue characterization with T1- and T2-weighted
images, a high spatial resolution, and a high sensitivity
for contrast enhancement contribute to the greater
• Screening for Liver Tumors in Diffuse Hepatic
– US can be used for initial screening, CT or MRI should
be used once cirrhosis sets in.
– In patients with equivocal findings on CT, MRI is
useful for its ability to accurately identify fatty
infiltration and small HCCs
• Incidentally Detected Lesions with Other
• Assessing Tumor Response to Surgery or
– The presence of enhancement along surgical margins
usually represents postoperative changes, but nodular
enhancement or a discrete soft-tissue mass at the
surgical margins indicates recurrence.
• A comprehensive MR imaging examination of
the liver should include T1-weighted
images,T2-weighted images and dynamic
multiphasic contrast-enhanced images,
preferably supplemented by chemical-shift
images and fat-saturation images.
• Single-shot fast-spin echo (SSFSE) is
recommended for coronal localizer imagesHASTE
• Each of the images is obtained in <1 second,
providing a rapid, motion-independent T2weighted survey.
• These sequences give an overview of the liver,
and differentiate solid lesions from cystic
lesions or hemangiomas, particularly with the
use of a heavily T2-weighted sequence
• Gradient-echo sequences are generally used for
• Spoiled gradient-echo (SGE) sequences allow
acquisition of sufficient sections in one breath
hold (about 20 sec) for complete liver coverage
and provide good SNR– FLASH
• Short tau inversion recovery (STIR) also may be
used to acquire T2WI
– these images have high soft-tissue contrast and
minimal signal from adipose tissue.
Dual Gradient-Echo In-Phase and
• This sequence is primarily used to detect and
characterize focal as well as diffuse steatosis
of the liver by using the chemical shift
cancellation artifact (also known as fat-water
cancellation artifact, black lining artifact, or
India ink artifact).
• Protons in water and fat precess at different
• Chemical shift
• At certain TE they are in-phase and at other TE
they are out of phase
• In phase TE images will have signals of water and
fat added together-both are bright
• Out of phase-fat is subtracted.
• In out of phase imaging fat containing lesions will
appear darker when compared to in-phase.
• Only when the lesions contain both fat and water.
• The characterization of primary focal liver
lesions such as hepatocellular carcinoma and
adenoma can be improved by using the
chemical shift cancellation artifact .
• These lesions may contain fat and water
within the same voxel, which can be detected
reliably with gradient-echo in- and opposedphase MR imaging.
• T1 2D or 3D gradient echo sequences (e.g.
– arterial phase : 20 - 25 seconds
– portal venous phase : 60 - 70 seconds
– equilibrium phase : 3 - 5 minutes
– hepatobiliary delayed phase : 10 - 30 minutes with
and without fat sat
• Extracellular agents are distributed within the
extracellular interstitial space.
– Lesion detection
– Lesion characterization
– Liver vasculature assessment.
• Gadolinium has seven unpaired electrons and is highly
• Gadolinium shortens the T1 (spin-lattice) and T2 (spinspin) relaxation times of adjacent water protons.
• These relaxation effects tend to cause signal
enhancement at T1-weighted imaging and signal loss at
• Appropriate evaluation of the liver requires imaging
during the arterial phase of extra-cellular contrast
enhancement, specifically the late hepatic arterial
phase, when the portal vein is only slightly enhanced
• Reticuloendothelial agents target the
reticuloendothelial system, particularly the
liver and spleen.
• Reflects the number of functioning
• Currently in clinical use include
superparamagnetic iron oxide (SPIO) particles.
• SPIO particles are phagocytosed by macrophages
throughout the body but are preferentially
entrapped by Kupffer cells, which line the hepatic
• SPIO particles act as a negative contrast agent.
Their superparamagnetic properties cause local
magnetic field inhomogeneity and result in
considerable T2 and T2* shortening.
• Tissues that accumulate SPIO particles thus show
reduced signal intensity, particularly on T2- and
T2*-weighted images, and to a lesser extent on
• Most liver tumors—whether benign or malignant,
primary or metastatic—are deficient in Kupffer
cells and do not exhibit SPIO particle uptake
• Thus, after an infusion of SPIO particles,
– Liver becoes preferentially darker
– Tumors become relatively hyperintense
• The primary exception to this rule occurs in focal
nodular hyperplasia, in which SPIO particles may
accumulate, with a resultant isointense or even
hypointense appearance of lesions in comparison
with the normal liver parenchyma
Axial T1-weighted spo
image, obtained after
injection of SPIO partic
before that of gadolini
shows negative enhan
of the background live
and clearly depicts the
Axial T1-weighted spoiled GRE image, obtained
during the late hepatic arterial phase of
enhancement after the administration of SPIO
particles and gadolinium, shows increased
conspicuity of the lesion (arrow).
• SPIO particles are most useful when combined
with gadolinium to create a double-contrast
• With this technique, the SPIO particles are
infused first and are followed later by
• The two agents synergistically improve lesionto-liver contrast on dynamic T1- images
because the background liver is darkened by
the SPIO particles while the lesion of interest
is lightened by gadolinium
Negative contrast enhancement effect of SPIO
particles in a 56-year-old man with cirrhosis
• Because mangafodipir is taken up only by
hepatocytes, hepatocyte-containing masses
(eg, HCC, focal nodular hyperplasia, and
hepatic adenoma) appear enhanced in 75% of
cases, whereas metastases generally are not
MRI in Diffuse Liver Diseases
• Homogenous- involves
disorders of hepatocytes
and reticuloendothelial cells
• Segmental- segmental fatty
liver and focal confluent
– subacute hepatitis
– Fatty liver
• Nodular- multiple abnormal nodular
intensities- includes disorders that
cause numerous nodular lesions
corresponding to iron deposits in
regenerative nodules or granulomas
– cirrhosis, Wilson's disease, and
• Perivascular involve the periportal
lymphatic channel and Glisson's
capsules congestive liver and
Budd-Chiari syndrome are usually
associated with periportal high
signal intensity of the liver.
DIFFUSE HOMOGENOUS DISTRIBUTION
• Hemochromatosis is an iron overload disorder resulting in hepatic
parenchymal or reticuloendothelial deposition of iron.
• On T2WI, the superparamagnetic effect of iron causes decreased
signal intensity of liver parenchyma in comparison with that of the
Gradient-echo T2* WI are more sensitive to magnetic susceptibility
effects. T1WI also show decreased signal intensity of liver
T2-weighted MR image shows decreased signal
intensity of liver, pancreas, and spleen when
compared with that of paraspinal muscle.
• Pathologically, steatohepatitis demonstrates varying degrees
of steatosis (fatty liver), mixed cellular inflammatory infiltrate
across the lobule, the presence of hepatocyte injury, and
• This condition is unrelated to alcohol abuse.
• Radiologically, steatohepatitis cannot be reliably distinguished
from other causes of fatty liver.
• The presence of >33% fat on liver biopsy was shown to be
optimal for detecting steatosis on radiological imaging
• Nonalcoholic steatohepatitis is sometimes associated with
acute hepatic failure, and in a minority of patients, the disease
progresses to cirrhosis.
• MR images• diffuse homogeneous increased signal intensity
on in-phase images and
• diffuse homogeneous low signal intensities on
opposed-phase T1-weighted images
Glycogen Storage Diseases
• Patients with this disease may also have
hepatocellular adenoma, manifesting as a lowattenuation tumor on conventional CT images
and as hyperintensity on T1- and T2-weighted
36-year-old man with glycogen storage disease. T1weighted spin-echo MR image shows low signal
intensity of normal hepatic parenchyma compared
with that of bone marrow.
Glycogen storage disease. T1-weighted spinecho MR image reveals homogeneously
increased signal intensity of hepatic
parenchyma compared with that of bone
marrow. Note round high-signal-intensity
tumor (arrow) in lateral segment.
T2-weighted spin-echo MR image shows tumor
with high signal intensity
• Fatty change in hepatocytes occurs in patients with
diabetes mellitus, obesity, transplanted liver, alcohol
abuse, and chemical toxicity.
• Segmental fatty liver is characterized by segmental
distribution of fatty infiltration, depending on regional
differences in perfusion.
• T1-weighted spin-echo MR images show slightly
increased signal intensity resulting from fatty
• In-phase MR images show similar intensity for normal
liver parenchyma and fatty changes.
• Opposed-phase T1-weighted MR images are the most
useful for detecting low signal intensity caused by fatty
• Subacute hepatitis is caused primarily by viral
infection, such as hepatitis B or C, or by drug use.
• When the liver is severely damaged, parenchymal
intensity is reduced on T1-weighted MR images
and increased on T2-weighted MR images.
• Segmental atrophy may manifest as abnormal
signal intensity (i.e., areas of focal confluent
fibrosis with abnormal signal intensity and
T1-weighted MR image reveals diffuse atrophy
of liver with irregular surface and decreased
signal intensity of left lobe (arrows).
T2-weighted MR image shows segmental
increase in signal intensity of left lobe
Post contrast gradient-echo T1-weighted MR
image -segmental delayed enhanced area
probably corresponding to segmental fibrosis.
• Cirrhosis, the chronic response to repeated episodes of hepatocellular
injury, is characterized by regeneration and fibrosis.
Common causes of cirrhosis include alcoholism and viral infections such
as hepatitis B and C.
• The role of imaging in cirrhosis is the early detection of HCC and the
differentiation of regenerative nodules from dysplastic nodules and HCC.
• Regenerative changes caused by cirrhosis appear throughout the liver as
small round masslike structures.
• These lesions appear as hypointense nodules on T2-weighted MR images,
are most apparent on gradient-echo images, and are believed to be
caused by deposition of hemosiderin in the regenerative nodules.
T2-weighted MR image reveals multiple
regenerative nodules with low signal
• In patients with Wilson's disease the biliary excretion of
copper is impaired, resulting in the accumulation of toxic
levels of copper in the liver, brain, and cornea.
• Copper has no ferromagnetic effect on MR imaging
because copper in hepatocytes may combine with proteins.
• The most common finding of Wilson's disease is cirrhotic
• Iron in regenerative nodules causes numerous small
nodular intensities scattered throughout the liver on T2weighted MR images.
T2-weighted spin-echo MR image shows
numerous small low-signal-intensity nodules
scattered throughout liver, probably
corresponding to iron in regenerative nodules
• Sarcoidosis, a common systemic granulomatous
disease, occasionally involves the liver, spleen, and
subdiaphragmatic lymph nodes.
• Noncaseating epithelioid granulomas with surrounding
fibrosis are present in the periportal region and portal
• T2-weighted MR images shows liver lesions as
numerous areas of low signal intensity and faint patchy
high-signal-intensity structures that corresponds to the
enhanced areas seen on contrast-enhanced T1weighted images.
• Such intensities may correspond histologically to
granulomas with surrounding fibrosis.
T2-weighted MR image shows faint patchy or
geographic high-signal-intensity lesions (large
arrows) in liver. Numerous small low-signalintensity nodules (small arrows) are also seen.
Gadolinium-enhanced gradient-echo T1weighted MR image reveals patchy or
geographically enhanced area
Congested liver is a common complication of congestive heart failure, constrictive
pericarditis, and right-sided heart failure resulting from pulmonary artery obstruction
caused by lung cancer.
T2-weighted MR images of patients with congested liver show periportal hyperintensity
and prominent perivascular zones of diminished attenuation resulting from presumed
MRI in focal liver lesions
Simple hepatic cyst. Axial contrastenhanced 3D GRE T1-weighted VIBE MR image
shows a simple cyst (arrow) with the typical
features of nonenhancement and low signal
Hepatic cysts in a patient with Caroli disease. Axial
contrast-enhanced 3D VIBE MR image shows cystic
dilatation of the biliary ducts manifesting as multiple
small, nonenhancing cysts. Note the presence of the
“central dot sign” (arrow).
The lesions exhibit low signal intensity on
both images and no enhancement after
contrast material injection.
• A hepatic haemangioma is a benign
hypervascular liver lesion. It is the most
common benign tumour of the liver, and the
most common liver tumour overall
• Blood supply is predominantly hepatic arterial
• T1 - hypointense relative to liver parenchyma
• T2 - intensely hyperintense relative to liver
• T1 C + (Gd) - often shows peripheral nodular
enhancement which progresses centripetally
(inward) on delayed images.
– haemangiomas tend to retain contrast on delayed (>5
minute) contrast-enhanced images.
– atypical haemangiomas may demonstrate slightly
altered enhancement patterns.
– in general delayed (1 hour) imaging may not be
helpful, since haemangiomas can have a variable
appearance that ranges from hypointensity to diffuse
and central enhancement.
PORTAL VENOUS PHASE
A hepatic hemangioma with the typical
findings of early peripheral nodular
enhancement and progressive centripetal
filling. These findings helped confirm the
• A dysplastic nodule is defined as a small cluster of
hepatocytes with dysplasia indicating the presence of
nuclear and cytoplasmic changes but without definite
histologic criteria for malignancy.
• Variable MR appearance
• Generally hypointense or, more commonly, hyperintense on
T1-weighted images and iso- or hypointense on T2weighted images, without prominent arterial phase
enhancement after contrast material administration.
• Dysplastic nodules are almost never hyperintense on T2weighted images
Axial unenhanced and contrast-enhanced 3D
GRE T1-weighted VIBE MR images
The lesions exhibit high signal intensity on
both images and no enhancement after
contrast material administration.
• Hepatic adenoma is a focal benign proliferation of
hepatocytes within an otherwise normal liver.
• MR imaging appearance of hepatic adenomas ranges
from mildly hypointense to hyperintense on T1weighted images.
• The high signal intensity is due to the presence of fat or
• On T2-weighted images, hepatic adenomas have a
nonspecific, heterogeneous, slightly hyperintense
• Immediate enhancement is seen on arterial phase
images after intravenous gadolinium chelate
administration but rapidly fades to near isointensity on
An adenoma (white arrow) with typical
immediate enhancement. Note also the
focal area of hemorrhage (black arrow).
Focal Nodular Hyperplasia
• Common benign tumor
• The origin of FNH is thought to be due to
hyperplastic growth of normal hepatocytes with a
malformed biliary draining system.
• Macroscopically, typical lesions demonstrate a
tumour which is often quite large with well
• A prominent central scar is usually noted with
radiating fibrous septae : <50% of cases.
• A large central artery is usually present with
spoke-wheel like centrifugal flow(no portal veins).
• Kupffer cells are present
MRI is both sensitive (70%) and specific (98%).
– iso to somewhat hypo intense
– hypo intense central scar
– iso to somewhat hyperintense
– hyperintense central scar
• T1 C+ (Gd) :
– gadolinium enhancement is similar to CT
intense early arterial phase enhancement
– iso intense to liver on portal venous phase
– central scar retains contrast on delayed scans
• T1 C+ (hepatobilliary contrast) : demonstrates
High T2 signal intensity with immediate lesion
enhancement, poor enhancement of the
central scar on the early phase image and
increased enhancement of the scar on the
delayed phase image
– iso or hyperintense compared to liver
– hyperintensity may be due to
• intratumoural fat
• decreased intensity in surrounding liver
• T1 C+ (Gd)
• enhancement is usually arterial and may be brief
– rapid wash out becoming hypointense compared to remainder
of the liver (96% specific). This is on account of the supply to
HCCs being from the hepatic artery rather than portal vein
– rim enhancement may persist (referred to as a capsule)
– the larger the lesion the more heterogeneous the enhancement
• T2 - variable, typically hyperintense
• A large HCC may have a number of
characteristic features, such as a
– mosaic pattern,
– a tumor capsule,
– extracapsular extension with formation of satellite
– vascular invasion, and
– extrahepatic dissemination, including lymph node
and distant metastases
• Hepatic metastases can be classified according to
their enhancement pattern into two categories:
– hypovascular and hypervascular.
– Colon, lung, prostate, gastric, and transitional cell
– Islet cell tumors, breast cancer, melanoma, thyroid
cancer, and carcinoid tumor
• These metastatic lesions usually demonstrate
low signal intensity on T1-weighted MR
images and are iso-to hyperintense on T2weighted images
• Delayed enhancement on contrast-enhanced
• Occasionally, they show early ring
Early phase contrast-enhanced 3D GRE T1weighted VIBE MR image shows hypovascular
metastases with low signal intensity and no
Hypervascular metastases are best seen during the
arterial phase of enhancement .Most of these
lesions have high signal intensity on T2-weighted
• Primary hepatic lymphoma is rare.
• Secondary involvement of the liver can occur in
up to 50% of patients with non-Hodgkin
lymphoma and 20% of patients with Hodgkin
• Lymphomatous lesions usually have low signal
intensity on T1-weighted MR images and variable
signal intensity on T2-weighted images.
• They usually enhance minimally just after
gadolinium administration and may show faint
peripheral rim enhancement on subsequent
Axial contrast-enhanced 3D GRE T1-weighted VIBE
MR image demonstrates two small, well-defined
hepatic lymphomatous deposits with faint
• Recent advances in MRI have led to a growing
interest in optimizing and applying functional
MRI methods for assessment of liver disease.
These methods include—but are not limited
to— diffusion-weighted imaging (DWI),
perfusion-weighted MRI, MR elastography
(MRE), and MR spectroscopy (MRS).
• DWI- Restricted diffusion observed in patients
with cirrhosis - reflects diminished capillary
• PWI-A prospective study of liver perfusion
parameters showed increased arterial flow and
distribution volume and decreased portal venous
flow in patients with advanced fibrosis and
• MRE-have tested the usefulness of the technique
for diagnosing hepatic fibrosis.
• MRS-for measuring hepatic fat content,
– with many studies showing strong correlations
between MRS and histologic grade of steatosis