diagnostic imaging of the liver

Gastro-Intestinal Tract

Liver

Mohamed Zaitoun

Assistant Lecturer-Diagnostic Radiology Department , Zagazig University Hospitals

EgyptFINR (Fellowship of Interventional

Neuroradiology)-Switzerlandzaitoun82@gmail.com

Knowing as much as possible about your enemy precedes successful battle

and learning about the disease process precedes successful management

Livera) Diffuse Liver Diseasesb) Infectionsc) Tumorsd) Traumae) Vascular Abnormalitiesf) Benign Hepatic Cysts g) Hepatic Calcificationsh) Hepatomegaly

a) Diffuse Liver Diseases :1-Hepatitis2-Cirrhosis3-Fatty Liver4-Focal Confluent Fibrosis5-Glycogen Storage Disease6-Gaucher’s Disease7-Hemachromatosis

1-Hepatitis :a) Causesb) Radiographic Features

a) Causes :1-Viral hepatitis :-Hepatitis A , B & C-Other viruses : cytomegalovirus, Epstein-Barr,

herpes simplex , rubella , yellow fever2-Chemical hepatitis :-Alcohol-Drugs : INH, halothane , chlorpromazine ,

phenytoin , methyldopa , acetaminophen-Toxins such as CCl4

b) Radiographic Features : U/S1-Acute Hepatitis :-In most cases , the liver appears normal -The liver parenchyma may have a diffusely

decreased echogenicity with accentuated brightness of the portal triads (starry sky) , periportal cuffing

-Hepatomegaly & thickening of the G.B. wall

2-Chronic Hepatitis :-In most cases , the liver appears normal-When cirrhosis develops , U/S may

demonstrate a coarse echotexture & other morphologic changes of cirrhosis

2-Cirrhosis :a) Definitionb) Pathologyc) Classificationd) Radiographic Features

a) Definition :-Diffuse process characterized by fibrosis

and the conversion of normal liver architecture into structurally abnormal nodules

b) Pathology :-3 pathologic mechanisms which in combination

create cirrhosis :cell death , fibrosis & regeneration

c) Classification :1-Micronodular (nodule 1 mm to 1 cm) in alcohol

intake2-Macronodular (up to 5 cm) in chronic viral

hepatitis

d) Radiographic Features : a) U/S :1-Volume redistribution2-Coarse echotexture3-Nodular surface4-Nodules5-Portal hypertension

1-Volume redistribution :-Early stages , the liver is enlarged-Advanced stages , the liver is often small with

relative enlargement of the caudate , left lobe or both in comparison with the right lobe

2-Coarse echotexture :-Increased echogenicity and coarse echotexture

are frequent observations in diffuse liver disease

3-Nodular surface :-Irregularity of the liver surface corresponds to the

presence of regenerating nodules and fibrosis4-Nodules (regenerative & dysplastic) :-Regenerative nodules (RN) , represents regenerating

hepatocytes surrounded by a fibrous septa (isoechoic or hypoechoic with a thin echogenic border)

-Dysplastic nodules , considered premalignant , 1 cm , they contain well differentiated hepatocytes , a portal venous blood supply and also atypical or frankly malignant cells

5-Portal hypertension :Ascites , splenomegaly and varices

b) CT :-CT is insensitive in early cirrhosis -More established findings : as U/S

3-Fatty Liver :a) Causesb) Radiographic Features

a) Causes :1-Obesity (most common cause)2-Alcohol3-Hyperalimentation4-Debilitation5-Chemotherapy6-Hepatitis7-Steroids , Cushing's syndrome

b) Radiographic Features1-U/S :-The liver echogenicity is higher than normal

, liver parenchyma becomes brighter than right kidney parenchyma

*N.B. >> Focal fatty change includes :Focal fatty infiltration and focal fatty sparing ,

both may mimic neoplastic involvementa) Focal fatty infiltration , regions of

increased echogenicity are present within a background of normal liver parenchyma

b) Focal fatty sparing , islands of normal liver parenchyma may appear as hypoechoic masses within a dense fatty infiltrated liver

-Features of focal fatty change include :a) Focal fatty sparing and focal fatty liver , both most

commonly involve the peripheral region of the medial segment of the left lobe (segment IV)

b) Sparing also occurs commonly by the gall bladder fossa and along the liver margins

c) Lack of mass effect , hepatic vessels as a rule are not displaced

d) Geographic margins are present , although focal fat may appear round , nodular , or interdigitated with normal tissue

e) Rapid change with time , fatty infiltration may resolve as early as within 6 days

f) CT scan of the liver will demonstrate corresponding regions of low attenuation

2-CT :-Fatty areas are hypodense , normal liver appears

relatively hyperdense-Liver less dense than spleen-Hepatic and portal veins appear dense relative to

decreased parenchymal density-Common focal fatty deposit : segment IV ,

anteriorly near fissure for falciform ligament

4-Focal Confluent Fibrosis :-Wedge shaped area of low attenuation on

noncontrast CT-Retraction of overlying liver capsule (90%)-Located in medial segment of left lobe

and/or anterior segment of right lobe in a cirrhotic liver

-May show delayed persistent enhancement

-Differential Diagnosis of liver lesions causing capsular retraction :

1-Metastases2-HCC (mainly the fibrolamellar type)3-Cholangiocarcinoma4-Cirrhosis (confluent hepatic fibrosis)5-Following trauma (including iatrogenic , e.g.

biliary drainage , biopsy , radiofrequency ablation)

6-Inflammatory pseudotumor

-Lesion (asterisk) of lower attenuation than adjacent liver parenchyma involving segment IV and mild retraction of liver capsule (arrowhead), which is typical of focal confluent fibrosis

Patient with alcoholic cirrhosis and focal confluent fibrosis , axial unenhanced CT shows progressive retraction of liver capsule over lesion (arrowhead) and moderate volume loss 

5-Glycogen Storage Disease :a) Definitionb) Radiographic Features

a) Definition :-Enzyme deficiency results in accumulation

of polysaccharides in liver and other organ

b) Radiographic Features :1-Primary liver findings :-Hepatomegaly-US : increased echogenicity (looks like fatty liver)-CT : increased density (55 to 90 HU)2-Other organs :-Nephromegaly3-Hepatic complications :-Hepatic adenoma

6-Gaucher’s Disease :a) Definitionb) Radiographic Features

a) Definition :-Glucocerebrosidase deficiency leads to

accumulation of ceramide in cells of the RES

b) Radiographic Features :1-Liver :-Hepatomegaly2-Spleen :-Splenomegaly (marked)-Focal lesions (infarcts) typically have low density (CT) and

are hyperechoic (US)3-Musculoskeletal :-Erlenmeyer flask deformity of femur-Generalized osteopenia-Multiple lytic bone lesions-Aseptic necrosis of femoral head

7-Hemachromatosis :a) Definitionb) Typesc) Radiographic Features

a) Definition :-Iron overload

b) Types :1-Primary Hemachromatosis (defect in intestinal

mucosa , increased iron absorption) :-Clinical finding is bronze diabetes : cirrhosis ,

diabetes mellitus & hyperpigmentation2-Secondary Hemachromatosis -Multiple transfusions in bleeders

c) Radiographic Features :1-US :-Hyperechoic liver2-CT :-Dense liver (>75 HU), much denser than spleen-Intrahepatic vessels stand out as low-density structures3-MRI :-Liver and spleen are markedly hypointense on T2-Other organs with decreased SI : lymph nodes , bone

marrow , pituitary , heart , adrenals , bowel-In primary hemachromatosis , pancreas also appears

hypointense

T2

b) Infections :1-Viral hepatitis2-Bacterial diseases (pyogenic abscess)3-Fungal diseases (candidiasis)4-Parasitic diseases (Amebic abscess ,

Hydatid disease & Bilharziasis)

1-Viral hepatitis :-See before

2-Bacterial diseases (pyogenic abscess) :a) Causesb) Radiographic Features

a) Causes :-Pathogens : Escherichia coli , aerobic

streptococci , anaerobes-Ascending cholangitis-Trauma , surgery-Pylephlebitis

b) Radiographic Features :1-U/S :-Cystic with the fluid ranging from echofree to

highly echogenic-Occasionally , gas producing organisms give rise

to echogenic fociFluid-fluid interfaces , internal septations & debris

have all been observed-The abscess wall can vary from well defined to

irregular & thick-May be multiple

2-CT :-Hypodense mass or masses with peripheral

enhancement , no fill-in-Double-target sign : wall enhancement

with surrounding hypodense zone (edema)-30% contain gas

3-Fungal diseases (candidiasis) :-In immunocompromised-Small abscesses spread throughout the

liver

4-Parasitic diseases :a) Amebic abscessb) Hydatid diseasec) Bilharziasis

a) Amebic abscess :1-Etiology2-Radiographic Features

1-Etiology :-Pathogen : Entamoeba histolytica

2-Radiographic Features :-Round or oval-shaped lesion -Irregular shaggy borders-Contiguity with the diaphragm , may be associated with

pleural effusion & lung collapse-Internal septations , 30%-Multiple abscesses , 25%

b) Hydatid disease : (Echinococcus)1-Etiology2-Classification3-Radiographic Features

1-Etiology :-Caused by infestation by the parasite

Echinococcus granulosus

2-Classification :a) Simple cyst containing no internal

architecture except sand (fine debris)b) Cysts with detached endocyst 2ry to

rupturec) Cysts with daughter cyst matrix (echogenic material between the daughter

cysts)d) Densely calcified masses

a) Simple cyst containing no internal architecture except sand (fine debris)

b) Cysts with detached endocyst 2ry to rupture

c) Cysts with daughter cyst matrix (echogenic material between the daughter

cysts)

d) Densely calcified masses

3-Radiographic Features :-Calcification-Internal floating shadows-Daughter cysts-Other cysts (especially in the lung)

c) Bilharziasis :1-Etiology2-Radiographic Features

1-Etiology :-Caused by Schistosoma-Causes periportal fibrosis , fine and coarse

2-Radiographic Features :a) U/S :-Widened echogenic portal tracts , sometimes

reaching a thickness of 2 cm-The porta hepatis is the region most often

affected-Initially the liver is enlarged , however as the peri-

portal fibrosis progress , the liver is contracted & the features of portal hypertension prevails

b) CT :-Prominent hypodense and hypovascular

periportal tracts secondary to periportal fibrosis

Unenhanced Portal Venous

Unenhanced Portal Venous

Unenhanced Portal Venous

c) Tumors :(I) Benign :1-Cavernous Hemangioma 2-Focal nodular hyperplasia3-Adenoma4-Hemangioendothelioma5-Mesenchymal Hamartoma(II) Malignant :1-Hepatocellular Carcinoma (HCC)2-Mets3-Lymphoma4-Hepatoblastoma

*How to detect the site of the focal >>Couinaud system >>-The liver is divided by the branches of the hepatic veins

into 8 segments starting at the caudate lobe & running in clock-wise direction

-LT lobe :*Segment I >> caudate lobe*Segment II & III divided by LT PV >> the furthest leftII >> lateral superiorIII >> lateral inferior

*Segment IV >>-Lies between the LT hepatic vein & middle

hepatic vein-Separated from segment II & III by the LT

hepatic vein-IVa >> medial superior-IVb >> medial inferiorDivided by the LT PV

-RT lobe :*Segment V >> anterior inferior*Segment VI >> posterior inferior*Segment VII >> posterior superior*Segment VIII >> anterior superiorThe RT lobe is divided by >>> RT hepatic vein into : antero-medial & postero-

lateral> RT branch of PV into : superior & inferior

(I) Benign :1-Cavernous Hemangioma 2-Focal nodular hyperplasia3-Adenoma4-Infantile Hepatic Hemangioendothelioma5-Mesenchymal Hamartoma

1-Cavernous Hemangioma :a) Incidenceb) Radiographic Features

a) Incidence :-Most common benign tumor of the liver-80% in females , hemangiomas may enlarge

particularly during pregnancy or estrogen administration

-Two types :1-Typical Hemangioma : Common-Small , asymptomatic , discovered incidentally2-Giant Hemangioma : > 5 cm-Uncommon

b) Radiographic Features :1-U/S :-Small < 3 cm , well defined , homogenous

and hyperechoic-Giant hemangiomas are heterogeneous-Posterior acoustic enhancement is common

2-CT : Fill in sign-Noncontrast : often hypoattenuating relative to

liver parenchyma-Arterial phase : typically discontinuous , nodular ,

peripheral enhancement (small lesions may show uniform enhancement)

-Portal venous phase : progressive peripheral enhancement with more centripetal fill in

-Delayed phase : further irregular fill in and therefore iso or hyperattenuating to liver parenchyma (fill in sign)

3-MRI : Light-bulb sign-Hyperintense (similar to CSF) on heavily T2

(light-bulb sign)-Post-gadolinium peripheral nodular

enhancement with centripetal fill-in-Imaging modality of choice

2-Focal Nodular Hyperplasia :a) Incidenceb) Radiographic Features

a) Incidence :-The 2nd most common benign liver mass

after hemangioma-More common in women in childbearing

period

b) Radiographic Features :1-U/S :-Often a subtle liver mass that is difficult to

differentiate from in echogenicity from the adjacent liver parenchyma

-The central scar may be seen as a hypoechoic linear or stellate area within the central portion of the mass , on occasion may be hyperechoic

-Doppler : highly suggestive, in that well developed peripheral and central blood vessel larger are seen , the blood vessels can be seen to course within the central scar which either a linear or stellate configuration (spoke-wheel vascularity)

2-CT :-Non-contrast : hypo or isodense but may

appear hyperdense if the rest of the liver is fatty , a hypodense central scar can be seen in up to 60% of lesions over 3 cm in size

-Arterial : FNH demonstrates bright arterial contrast enhancement except for the central scar which remains hypodense

-Portal : the lesion becomes isodense to liver -Delayed : the scar demonstrates

enhancement on delayed scans in up to 80% of cases

Arterial Venous Delayed

3-MRI :-Lesion isointense to liver , central scar

hyperintense on T2-Arterial enhancement-Delayed enhancement of central scar-Angiography : hypervascular lesion

Axial T2 shows a large FNH lesion (straight arrow) that is isointense relative to the surrounding liver parenchyma, the central scar (curved arrow) has slightly higher signal intensity than the lesion

3-Adenoma :a) Incidenceb) Radiographic Features

a) Incidence :-Less common than FNH-More common in women , increase incidence now due to

usage of oral contraceptive agents-Anabolic steroids (typically young men) , Glycogen storage

disease-The tumor may be asymptomatic , but often the patient or

the physician feels a mass in the right upper quadrant-Pain may occur as a result of bleeding or infarction within

the lesion , the most alarming manifestation is shock caused by tumor rupture and hemoprotineum

b) Radiographic Features :1-U/S :-Solitary and large at the time of diagnosis (5-15cm)-Non specific , the echogenicity may be hyperechoic (most

common) , hypoechoic , isoechoic or mixed-With hemorrhage , a fluid component may be evident

within or around the mass and free intraperitoneal blood may be seen

-A hypoechoic halo of focal fat sparing is also frequently seen

-Colour Doppler may show perilesional sinusoid

2-CT :-Unenhanced : they are well marginated and

isoattenuating to liver-On contrast administration they demonstrate

transient relaitvely homogenous enhancement returning to near isodensity on portal venous and delayed phases

-The density of these tumors is variable depending on :

Fresh hemorrhage , may be hyperdenseFat content may make the mass hypodense3-MRI :-High in T1 & T2

Unenhanced Arterial

Portal Delayed

4-Infantile Hepatic Hemangioendothelioma :

a) Incidenceb) Radiographic Features

a) Incidence :-It is a rare tumor that may occur as a

solitary lesion or multifocal nodules ranging in size from few mm upto 15 cm

-Most common benign pediatric liver tumor-85% present at < 6 months-Associated cutaneous hemangiomas in

50%

b) Radiographic Features :1-US :-Appears as a complex, mostly solid hepatic lesion

with variable hypo- and hyperechoic echotexture-In cases of significant arteriovenous shunting,

dilated hepatic vasculature with prominent blood flow at Doppler US is typical

-If large vascular spaces are present, anechoic regions with detectable flow may be seen

-The lesions are often well demarcated from the surrounding liver parenchyma

Transverse US image shows several small, well-demarcated, homogeneous hypoechoic lesions (arrowheads) in the liver

Color Doppler image shows peripheral flow around some of the lesions

Diffuse form of Hemangioendothelioma in a 10-week-old girl with severe hypothyroidism, (a, b) Transverse (a) and longitudinal (b) US images show numerous large masses (* in a) replacing the liver and compressing the inferior vena cava (arrow in a), AO in a = aorta, (c) Longitudinal color Doppler image shows a direct portal vein-to-hepatic vein shunt

2-CT :-At unenhanced CT, manifests as a well-defined

mass that is hypoattenuating relative to the normal liver parenchyma, in about 16%-40% of cases, the lesion is heterogeneous with central high-attenuation areas due to hemorrhage or calcifications

-At contrast-enhanced CT, the enhancement pattern may resemble that of an adult giant hemangioma, with “nodular” peripheral puddling of contrast material in the early phase, subsequent peripheral pooling, and central enhancement with variable delay, in larger tumors, central enhancement is often lacking due to fibrosis, hemorrhage, or necrosis, conversely, small lesions, which tend to be multifocal, frequently enhance completely and typically do not demonstrate hemorrhage or necrosis

CT+C, obtained in the early portal venous phase, shows peripheral corrugated enhancement of the masses (arrowheads) and compression of the inferior vena cava (arrow), (e) Delayed phase CT image shows centripetal enhancement of the masses

Axial CT scan post-contrast arterial phase at the level of the kidneys showed diffused hepatic masses with intense peripheral enhancement and central non-enhancing areas, B) Venous phase shows diffused enhancement of the lobulated liver segments

3-MRI :*T1 : low signal intensity *T2 : high signal intensity -In tumors with arteriovenous shunting and high

blood flow, flow voids may be observed on T2-Because of the simultaneous presence of

hemorrhage, necrosis, and fibrosis, the mass often appears heterogeneous on both T1 & T2

*T1+C : the lesions usually show an enhancement pattern similar to that described at CT

A) Axial unenhanced T1 shows diffused nodules with low signal intensity, B) Coronal T2 shows diffuse high signal intensity nodules occupying almost the entire abdomen

A) Axial MRI fat suppression shows diffused high signal nodules, B) Sagittal MRI post gadolinium shows enhancement of the nodules 

5-Mesenchymal Hamartoma :a) Incidenceb) Radiographic Features

a) Incidence :-2nd most common benign tumor in pediatric

population-It typically occurs in children and neonates,

with most cases presenting within the first two years of life

-Male predominance (2:1)

b) Radiographic Features :-Mesenchymal hamartomas can show a wide

spectrum of radiological features, from being :1-Predominantly cystic tumor, to2-Multiseptated cystic tumor, to3-Mixed solid and cystic tumor, to 4-Even a completely solid tumor-The dominant radiographic pattern, however, is a

large (often around 12-15 cm), predominantly cystic mass with internal septations, there can be considerable variation in the size of septae and cystic spaces

1-US :-It usually appear as a multiseptated cystic

lesion interspersed with solid components

2-CT :-On unenhanced CT,  it usually has a

heterogeneous appearance, the stromal elements often appear hypoattenuating, whereas the cystic components have water attenuation, the appearance of cystic and solid portions has been likened to Swiss cheese

-On a postcontrast CT scan, solid portions or thick septa of the tumors can show heterogeneous enhancement

(a) Transverse US image shows cystic (arrowheads) and solid (T) portions of the tumor and adjacent normal liver (*), (b) Longitudinal color Doppler image shows no flow to the cystic component, which contains low-level echoes (arrowhead), minimal flow is seen in the solid component (arrows)

Mesenchymal hamartoma in a 2-year-8-month-old boy, A. US shows a large, multiseptated cystic tumor in the right lobe of the liver. The septa of the tumor (arrows) are very thin and regular in thickness, B. CT+C shows a large cystic tumor with fine enhancing septa (arrows) in the liver, there is no solid portion or calcification within the tumor

Mesenchymal hamartoma in a 7-year-2-month-old boy, A. US shows a huge, mixed solid and cystic tumor, the echogenic materials and fluid-fluid levels (arrows) are noted in the cystic portions of the tumor, the solid portion of the tumor is hyperechoic (*), B. Color Doppler US shows vascularity along the thick septa and solid portion of the tumor, C. A pre-contrast CT scan shows a low attenuating tumor in the right lobe of the liver, note the fluid-fluid levels due to an intracystic hemorrhage within some of the cystic areas (arrows), D. On a post-contrast CT scan, the solid portion of the tumor shows heterogeneous enhancement (arrows)

Coronal CT image obtained with intravenous and oral contrast material shows the mixed cystic (arrowheads) and solid (T) tumor replacing the left hepatic lobe, * = normal live

3-MRI :-The appearance of mesenchymal hamartoma

depends on the cystic versus stromal (mesenchymal) composition of the mass, as well as the protein content of the fluid in the cysts

-Solid portions may appear hypointense to adjacent liver on both T1 and T2 owing to fibrosis

-The cystic portions are generally close to water signal intensity on T2 and demonstrate variable signal intensity on T1, depending on the protein content of the cyst fluid

-After intravenous administration of gadolinium contrast material, enhancement is mild and limited to the septa and stromal components

Mesenchymal hamartoma of the liver in a 2-year-old boy, * = normal liver,  (a) Axial T2 shows the markedly hyperintense mass containing thin septa (arrows), (b) Coronal T1 shows that the mass (arrows) is homogeneously hypointense relative to the liver, (c) Coronal T1+C obtained at the same level shows that enhancement is limited to the septa (arrows)

These (a) coronal and (b) axial T2 exquisitely depict the massive size of the mesenchymal hamartoma with multiple cystic areas (C) of varying sizes, few solid areas (S) and internal septations, the solid areas are hyperintense to normal liver (L)

(a) T2 shows hyperintensity, (b) T1 shows hypointensity

(II) Malignant :1-Hepatocellular Carcinoma (HCC)2-Mets3-Lymphoma4-Hepatoblastoma5-Angiosarcoma

1-HCC :a) Incidenceb) Radiographic Featuresc) Fibrolamellar HCC

a) Incidence :-One of the most common malignant tumors-More in men-Incidence : Alcoholic cirrhosis Hepatitis B & C

b) Radiographic Features :1-U/S :-Typically a small focal HCC appears

hypoechoic compared to normal liver-Larger lesions are heterogeneous due to

fibrosis , fatty change , necrosis and calcification

-A peripheral halo of hypoechogenicity may be seen with focal fatty sparing

2-CT :-Several pattern may be seen :a) Focal HCC :-Large usually hypodense mass-May have necrosis , fat , calcificationb) Multifocal HCC :-Multiple masses of variable attenuation lesions-May also have central hypodense necrotic portionsc) Diffuse HCC :-May be difficult to distinguish from associated

cirrhosis

-Enhancement pattern is the key to correct assessment of HCC , usually the mass enhances vividly during early arterial (25 seconds) and then washes out becoming indistinct or hypodense compared to the rest of the liver at the portal phase

Unenhanced Arterial Venous

Unenhanced Arterial

Venous Delayed

3-MRI :-T1 : Hypo , iso or Hyper (due to fat

degeneration)-T2 : Hyperintense-T1+C : enhancement is usually arterial and

may be brief , rapid wash out becoming hypointense c.f. remainder of the liver (96% specific) , this is on account of the supply to HCC being from the hepatic artery rather than portal vein

4-Angiography : Hypervascular , AV shunting is typical & dilated arterial supply

42-year-old man with HCC and hepatitis B-related cirrhosis: multiphasic MR technique with gadoxetate disodium. (a, b) Gadoxetate disodium-enhanced T1-weighted 3D GRE show large hypointense mass on (a) precontrast image with (b) hyperenhancement in late hepatic arterial phase, (c) Portal venous and (d) transitional phase images show apparent washout of contrast material from tumor, (e) Mass is hypointense relative to strongly enhanced liver parenchyma on hepatobiliary phase image obtained at 20 minutes after injection

**N.B. :-MRI allows differentiation of dysplastic nodules from HCC

as the dysplastic nodules are :1-Hyperintense on T12-Hypointense on T23-Lack of enhancement in the arterial phase4-Enhance in the portal venous phase and appear

iso/hyperintense to liver parenchyma -The regenerative nodules have variable intensity on T1,

hypointense on T2 with an enhancement pattern similar to normal liver parenchyma and without abnormal enhancement during the arterial phase

MRI of the dysplastic nodule, (a) T1 showing a hyperintense dysplastic nodule in the left lobe of the liver, (b) Nodule is characteristically hypointense on T2, (c) Non enhancing after IV gadolinium administration

Small HCC in segment 8 of the liver, (a) T1 showing a small hypointense nodule adjacent to the right hepatic vein, (b) Nodule is characteristically hyperintense on T2, (c) Enhancement during arterial phase after administration of IV gadolinium

c) Fibrolamellar HCC :1-Incidence2-Radiographic Features3-Differential Diagnosis

1-Incidence :-Typically these tumors occur in young

adults (20 to 40 years of age)-Unlike HCC they do not have an

association with cirrhosis, alcoholism or hepatitis B / C infection, i.e. it occurs in a non-cirrhotic liver

2-Radiographic Features :a) USb) CTc) MRI

a) US :-Fibrolamellar HCCs have nonspecific

sonographic features and are seen as well-defined masses of variable echogenicity on ultrasound

-Multiphasic CT using a liver protocol or dynamic contrast-enhanced MRI is usually required for further characterization

Fibrolamellar hepatocellular carcinoma (HCC) in 23-year-old woman, transverse gray-scale ultrasound image shows large heterogeneous echogenic lesion (curved arrow) in liver, echogenic strands in center of lesion (straight arrow) represent central scar, ultrasound features of fibrolamellar HCC are usually nonspecific

b) CT :-Usually present as large heterogeneous lesions (mean

diameter, 13 cm)-Most of these tumors are well defined and have a lobulated

outline, however, fibrolamellar HCC may also be ill-defined

-The tumors are predominantly hypoattenuating on the unenhanced images

-Calcification is commonly seen-Central stellate scar is typically seen, the presence of a

central scar is not pathognomonic of fibrolamellar HCC and has been reported in many benign and malignant liver lesions, however, a large scar (width > 2 cm) and presence of radiating fibrotic bands or septa are more common in fibrolamellar HCC

-Furthermore, presence of calcifications within the central scar is a useful diagnostic feature

-Tumor necrosis may be seen, but intratumoral hemorrhage is uncommon

Fibrolamellar hepatocellular carcinoma in 16-year-old girl, A, Axial unenhanced CT shows hypoattenuating mass (arrow) with central calcification (arrowhead), B, Axial CT+C in arterial phase shows that tumor (curved arrow) is hyperattenuating compared with liver parenchyma, central scar does not show any enhancement (straight arrow), C, Axial CT+C in portal phase shows tumor is still hyperattenuating (curved arrow) compared with adjacent liver parenchyma (straight arrow), D, Axial CT+C in delayed phase shows washout in mass (curved arrow), which is now hypoattenuating. Central scar shows delayed enhancement (straight arrow)

(a) Unenhanced, (b) Arterial phase, (c) Venous phase, (d) equilibrium phase

c) MRI :*T1 : hypointense *T2 : hyperintense-The fibrous central scar is typically hypointense on

both T1 and T2-This feature can help to distinguish fibrolamellar

HCC from FNH because the central scar in the latter is predominantly T2 hyperintense, the presence of intralesional fat has not been reported in fibrolamellar HCC

*T1+C : contrast enhancement characteristics of fibrolamellar HCC mimic the patterns seen on CT, showing marked heterogeneous contrast enhancement on the arterial phase and becoming isointense or hypointense on the portal venous and delayed phase

27-year-old woman with fibrolamellar hepatocellular carcinoma, coronal T1+C shows hypervascular mass (arrow) with central scar, tumor thrombus is present in portal vein (arrowhead)

Fibrolamellar hepatocellular carcinoma in 29-year-old man, A, Axial T1 shows mildly hypointense heterogeneous mass in liver (arrow) containing T1-hypointense central scar (arrowhead), B, Axial T2 shows that tumor (arrow) has heterogeneous high signal intensity, central scar is hypointense on T2 (arrowhead), C, Axial 3D gradient-echo fat-saturated T1+C in arterial phase shows heterogeneous enhancement within mass (arrow), no enhancement is seen within central scar (arrowhead), D, Axial T1+C in portal phase shows that tumor (arrow) is mildly hyperintense compared with liver, partial enhancement is seen in central scar (arrowhead), E, Axial T1+C in delayed phase shows that tumor (arrow) is isointense to mildly hyperintense compared with liver. Central scar shows almost complete enhancement (arrowhead)

3-Differential Diagnosis :From liver lesions with a central scar1-FNH2-Hemangioma (especially if large)3-HCC (Fibrolamellar type)4-Cholangiocarcinoma (peripheral type)5-Hepatic adenoma , metastases

(occasionally)

2-Metastases :a) Incidenceb) Radiographic Features

a) Incidence :-18 to 20 times more common than HCC-The most common primary tumor sites :GB , Colon , Stomach , Pancreas , Breast &

Lung

b) Radiographic Features :1-U/S :a) Echogenic metastasesb) Hypoechoicc) Target d) Calcifiede) Cysticf) Diffuse

a) Hyperechoic :-Gastrointestinal origin or from HCC-The more vascular the tumor , the more

likely the lesion to be echogenic-Renal cell carcinoma , carcinoid ,

choriocarcinoma , vascular primaries & islet cell carcinoma

b) Hypoechoic :-Hypovascular -Breast , lung , lymphoma , esophagus , stomach

& pancreas-Multiple hypoechoic hepatic masses is more

typical of primary NHL of the liver or lymphoma associated with AIDS , however lymphomatous masses may appear anechoic & septated , mimicking hepatic abscesses

c) Bull’s eye (target pattern) :-Peripheral hypoechoic zone -The appearance is nonspecific & common ,

although it is frequently identified in metastases from bronchogenic carcinoma

d) Calcified metastases :-Marked echogenicity & distal acoustic shadowing-Mucinous adenocarcinoma , osteosarcoma ,

chondosarcoma , teratocarcinoma , neuroblastoma

-Calcium may appear as large , echogenic & shadowing foci or more often shows innumerable tiny punctate echogenicities without clear shadowing

e) Cystic metastases :-Necrosis in sarcoma , cystic growth pattern

as in cystadenocarcinoma of ovary & pancreas & mucinous carcinoma of colon

f) Diffuse (infiltrative) :-Breast , lung & malignant melanoma-The diagnosis can be difficult if the patient

has a fatty liver from chemotherapy

2-CT :-Best seen on portal venous phase images

except for hypervascular lesions (arterial phase)

-Small lesions may fill in on delayed scans-Peripheral washout sign (when seen) is

characteristic of metastases

3-Lymphoma :-Secondary involvement occurs in up to 50

% of patients with systemic lymphoma , but it frequently occult , primary hepatic lymphoma is very rare

-Multiple hypoechoic hepatic masses + solid masses at the spleen , kidney , chest …

+ lymphadenopathy

NHL in a 16-year-old girl, (a) US scan shows a large hypoechoic nodule (M) in the right hepatic lobe, K = kidney, L = liver, (b) CT+C shows low-attenuation nodular lesions (arrowheads), a few discrete lesions are evident in both hepatic lobes, with small nodules in the spleen and right kidney

4-Hepatoblastoma :1-Incidence2-Radiographic Features

1-Incidence :-Most common primary malignant liver tumor

in children-Age : < 2 years

2-Radiographic Features :a) US :-Large hepatic mass-Mixed echogenicity (US), often hyperechoic relative

to adjacent liver

b) CT : -Sharply circumscribed mass that is slightly

hypoattenuating relative to adjacent liver parenchyma on unenhanced & contrast enhanced, septa and periphery of the tumor may enhance

-Calcification , 50%-Metastases : lungs > lymph nodes , brain

Transverse US image shows the hyperechoic mass with a lobular margin and hypoechoic septa (arrowheads), arrow = portal vein

Calcification

(a) Axial CT image obtained in the arterial phase of enhancement shows a circumscribed slightly hypoattenuating mass (arrowheads), (b) CT image obtained in the portal venous phase shows more heterogeneous, lobular enhancement (arrowhead), although the mass is still hypoattenuating relative to adjacent liver

CT+C

c) MRI : *T1 : hypointense*T2 : hyperintense ,septa are hypo in T1 &

T2 and enhance, hemorrhage appears hyperintense in T1

*T1+C : the septa enhance

(a) CT+C shows that the tumor enhances less than normal liver, some septa enhance (arrowheads), (b) Coronal T2 shows hyperintense nodules with hypointense septa in between (arrowheads), (c) Coronal T1+C shows enhancement of the septa and capsule (arrowheads)

5-Angiosarcoma :a) Incidence :-Angiosarcoma is a rare malignant tumor of

vascular origin that can arise anywhere in the body, including the liver

-Most commonly affecting elderly men

b) Radiographic Features :1-US :-May reveal multiple nodules, a large mass,

or both or diffuse heterogeneous echotexture of the entire liver

-The echogenicity of the nodules varies depending on the amount of hemorrhagic or necrotic change

2-CT & MRI:-At unenhanced study, the nodules are

generally hypoattenuating to normal liver but may contain hyperattenuating foci, which represent acute hemorrhage

-Enhanced study: mimics the intense peripheral nodular enhancement pattern of cavernous hemangioma

63-year-old man with multifocal angiosarcoma, (A) Unenhanced helical CT scan shows multiple masses (arrows) that are hypoattenuated to liver and hypo- and isoattenuated to vessels, (B) Arterial phase CT+C shows heterogeneous enhancement of tumors (long arrows), most of which are hyperattenuated to normal liver but hypoattenuated to aorta, one lesion (short arrow) is hypoattenuated to both liver and aorta, (C) Portal venous phase contrast-enhanced helical CT scan shows that most lesions that were hyperattenuated in B (long arrows) are now nearly isoattenuated to liver, but are hypoattenuated to vessels., large lesion (short arrow) remains hypoattenuated to both liver and vessels

54-year-old man with multifocal angiosarcoma, arterial phase (A) and portal venous phase (B) CT+C show large infiltrative mass (large straight arrows) involving entire left hepatic lobe, small mass (small straight arrow) in right hepatic lobe, and splenic metastasis (curved arrow), tumors are hypoattenuated to surrounding liver and aorta, note masses remain hypoattenuated to surrounding liver and aorta during portal venous phase (B)

Angiosarcoma in a 62-year-old man, transverse CT+C shows multiple hypoattenuating liver lesions, some with foci of enhancement (arrowheads), which are of decreased attenuation compared with the aorta

Angiosarcoma associated with a chronic organized subcapsular hematoma (arrowheads) in a 76-year-old man, (a) Transverse CT in the portal phase demonstrates a heterogeneous enhancement pattern in the lesion (arrows), (b) Transverse contrast-enhanced dynamic delayed-phase CT scan demonstrates progressive enhancement over time (arrows), (c) Transverse T1 shows a massive tumor (arrow) in the vicinity of a chronic organized subcapsular hematoma (arrowheads), the lesion contains focal areas of high intensity, which suggest hemorrhage, (d) Transverse fat-saturated T2 shows the marked heterogeneous appearance of the lesion (arrows) and hematoma (arrowheads)

(a) Axial T1 shows a well-defined focus of high signal intensity (arrowhead) at the margin of the tumor, a finding consistent with hemorrhage, * = normal liver, (b) Coronal T2 shows that the mass is predominantly hyperintense with dark septa (arrowheads). * = normal liver

Angiosarcoma in a 37-year-old man with known aplastic anemia, (a) Transverse T1 shows a diffuse lesion involving almost the entire posterior segment of the right lobe of the liver, numerous small nodules of high intensity suggest a focal area of hemorrhage, diffuse decrease in signal intensity in the liver, spleen (not shown), and bone marrow is consistent with patient’s known secondary hemochromatosis, (b) Transverse fat-saturated T2 shows compartmentalization within the lesion that contains numerous focal areas of high intensity

Angiosarcoma in a 65-year-old man, (a) Transverse T1 shows multiple low-intensity lesions (arrows) that contain focal areas of slightly high T1, (b) Transverse fat-saturated T2 shows heterogeneous signal intensity throughout the dominant mass, fluid-fluid levels can be seen in smaller satellite lesions (arrows)

d) Trauma :1-Incidence2-Types3-Grading4-Radiographic Features

1-Incidence :-The liver is the most common

intraabdominal site of injury , however , one must inspect other organs (spleen , bowel) for coexistent trauma

-The predominant site of hepatic injury in blunt trauma is the right lobe in particular the posterior segment

2-Types :a) Laceration (most common)b) Hematoma , subcapsular or

intraparenchymalc) Active hemorrhaged) Major hepatic vein injurye) AV fistula

3-Grading :

4-Radiographic Features :a) U/S :- < 24 hrs following injury , the fresh hemorrhage is

echogenic- Within the 1st week , the hepatic laceration

becomes more hypoechoic & distinct as a result of resorption of devitalized tissue & ingress of intestinal fluid

- At 2 or 3 weeks later , the laceration becomes increasingly indistinct as a result of resorption of the fluid & filling of the spaces of the granulation tissue

< 24 hrs

1 week

2 weeks

b) CT :-Lacerations appear as irregular linear /

branching areas of hypoattenuation -Hematomas appear as a hypodensity

between the liver and its capsule (and can be differentiated from intra-peritoneal hematoma as these distort the liver architecture) or can be intraparenchymal

-Acute hematomas / hemorrhage are typically hyperdense (40-60HU) compared to normal liver parenchyma

Lacerations can be stellate , like the example on the left or branching like the one on the right

CT+C shows linear low-attenuation defect crossing the posterior aspect of the right lobe of the liver representing a laceration

CT+C shows multiple linear and branching low-attenuation areas in the right hepatic lobe (arrows) that represent lacerations

Subcapsular hematoma

CT+C shows multiple subcapsular hematomas in the right and left hepatic lobes (arrows) , multifocal intraparenchymal hematomas are also seen (arrowheads)

CT+C shows a 5-cm intraparenchymal hematoma in the medial segment of the left hepatic lobe (arrow) , arrowheads indicate associated hemoperitoneum in the right subphrenic space

Unenhanced CT shows a high-attenuation hematoma in the anterior segment of the right hepatic lobe (arrow) , note the halo of low attenuation surrounding the hematoma (arrowheads)

e) Vascular Abnormalities :1-Portal Hypertension2-Portal Vein Thrombosis3-Budd-Chiari Syndrome (BCS)4-Arterio-Portal Shunting in Liver5-Hepatic Artery Aneurysm

1-Portal Hypertension :a) Definitionb) Etiologyc) Radiographic Features

a) Definition :-Hepatic wedge pressure >10 mm Hg

b) Etiology :1-Presinusoidal2-Sinusoidal3-Postsinusoidal

1-Presinusoidal :-Portal vein thrombosis-Extrinsic compression of portal vein-Schistosomiasis 2-Sinusoidal :-Cirrhosis3-Postsinusoidal :-Budd-Chiari syndrome-Congestive heart failure

c) Radiographic Features :-PV diameter > 13 mm-Portosystemic venous collaterals (Varices) :

gastro-oesophageal junction , para-umbilical vein , spleno-renal & gastro-renal , intestinal & hemorrhoidal

-Splenomegaly-Ascites-In CT, contrast enhancement of paraumbilical

vein (pathognomonic)

Dilated PV

Recanalized paraumbilical vein

Varices

2-Portal Vein Thrombosis :a) Etiologyb) Radiographic Features

a) Etiology :-1-Malignancy (HCC , liver mets , CA

pancreas)2-Cirrhosis3-Chronic pancreatits, hepatitis4-Septicemia , trauma , splenectomy 5-Portocaval shunts , pregnancy

b) Radiographic Features :1-U/S :-Acute thrombosis may be difficult to detect with

grey-scale imaging alone as the thrombus will be hypoechoic , with time it becomes more echogenic and easier to detect

-Colour Doppler will of course be able to demonstrate absent flow in the portal vein and even detect partial thrombosis

-Cavernous Transformations of the PV : numerous wormlike vessels at the porta hepatis which represent periportal collateral circulation , this pattern is observed in long standing thrombosis requiring up to 12 months to occur , so it is more likely to develop with benign disease

2-CT :-Non-contrast scans are usually incapable of

demonstrating the thrombus, except is some acute cases where the thrombus is hyperdense

-The diagnosis can only reliably be made on portal venous phase contrast enhanced studies , complete or partial non-opacification of part of or the whole portal vein and its branches

-Importantly the thrombus itself should not enhance , if enhancement is present then this strongly suggests that the thrombus is not bland but rather represents tumor thrombus most frequently from HCC

-Cavernous transformation appears as multiple small periportal vessels which represent dilated collateral veins

-Associated findings of portal hypertension may of course be evident

PV thrombus

Cavernous transformation of the PV

Cavernous transformation of the PV

3-Budd-Chiari Syndrome (BCS) :a) Definitionb) Clinical Picturec) Etiologyd) Radiographic Featurese) Differential Diagnosis

a) Definition :-Occlusion of the lumina of the hepatic veins

with or without occlusion of the lumen of the IVC

b) Clinical Picture :1-Ascites2-Pain3-Hepatomegaly4-Splenomegaly

c) Causes :1-Idiopathic : 50%-75%2-Secondary : 25%-50%-Coagulation anomalies , clotting disorders ,

polycythemia-Tumors : HCC , RCC-Trauma-Oral contraceptives , chemotherapy

d) Radiographic Features :1-U/S :-Partial or complete inability to see the hepatic

veins , stenosis with proximal dilatation , intra-luminal echogenicity , thickened walls , thrombosis & extensive intra-hepatic collaterals

-Hemorrhagic infarction appears hypoechoic by US-Caudate lobe is often spared (emissary veins drain

directly into the IVC) and appears enlarged , small right lobe

2-CT : Mottled appearance-Inhomogeneous mottled liver with delayed

enhancement in the periphery of the liver and around the hepatic veins = nutmeg liver (contrast is prevented from diffusing through the liver in a normal manner , this results in a mottled pattern of contrast enhancement in the arterial and early portal venous phase with decreased enhancement of the liver periphery)

-Peripheral zones of the liver may appear hypoattenuating because of reversed portal venous blood flow

-Caudate lobe enlargement and increased contrast enhancement compared with the remainder of the liver

-Inability to identify hepatic vein

CT+C of 30-year-old woman with Budd-Chiari syndrome, note patchy enhancement of liver (arrow) and absence of hepatic veins, Asterisk = presence of ascites

CT+C of 30-year-old woman with Budd-Chiari syndrome. Note massive enlargement of caudate lobe (CL) and patchy enhancement of liver (arrow). Asterisk = presence of ascites, arrowhead = inferior vena cava

CT+C of 19-year-old woman with subacute Budd-Chiari syndrome. Note absence of hepatic veins, enlargement of liver, compression of inferior vena cava, and presence of ascites (asterisks), Arrowhead = inferior vena cava

15-year-old girl with acute Budd-Chiari syndrome who presented with acute inferior vena cava (IVC) thrombosis, A, CT+C shows enlarged caudate lobe (CL) and lack of opacification of IVC; these findings indicate presence of acute thrombosis, Arrowhead = thrombosed IVC, B, CT+C obtained at lower level than A shows extension of IVC thrombosis down to level of renal veins, renal veins are also thrombosed (arrowheads)

44-year-old woman with Budd-Chiari syndrome, axial CT+C show enlarged liver (arrow) with heterogeneous enhancement with central hyperattenuation, note caudate lobe (CL) enlargement, large gastric varices (arrowhead, B), and lack of visualization of hepatic veins and inferior vena cava (IVC)

CT+C shows ascites and stronger enhancement in the caudate lobe and central portion of the liver parenchyma than in the periphery

CT+C shows patchy enhancement of the liver parenchyma, hypertrophy of the left hepatic lobe and thrombosis of the hepatic veins and IVC (arrow)

Early and delayed phases of liver enhancement

e) Differential Diagnosis :-Hepatic venoocclusive disease which

causes progressive occlusion of small vessels , is clinically indistinguishable from BCS

Caused by :1-Bone marrow transplantation2-Chemotherapy3-Jamaican bush tea

4-Arterio-Portal Shunting in Liver :a) Definitionb) Types

a) Definition :-Refers to abnormal shunt or fistulous

connection between the portal venous system and a hepatic arterial system within the liver

b) Types :1-Tumorous Shunt :-Occurs with hepatocellular carcinoma-Trans-tumoral shunt is due to abnormal communication

between the feeding artery and draining vein of the tumor which results in increased vascularity around the tumor manifested as peritumoral transient hepatic attenuation differences (THAD)

-The portal vein may show early enhancement in dynamic arterial scan without enhancement of its main tributaries the splenic and superior mesenteric veins

-THAD refer to areas of parenchymal enhancement visible during the hepatic artery phase on helical CT , t hey are thought to be a physiological phenomenon caused by the dual hepatic blood supply , occasionally they may be associated with hepatic tumors such as HCC

PV enhancement during arterial phase

PA shunt with HCC

THAD

AP shunt

2-Non-Tumorous Shunt :-Mainly due to liver biopsy and other hepatic

intervention-Also may occur due to liver cirrhosis

5-Hepatic Artery Aneurysm :-Decreasing order of frequency of abdominal

aneurysms : aorta > iliac artery > splenic artery > hepatic artery

-10% of patients with hepatic artery aneurysm have sudden rupture

-Hepatic pseudoaneurysm may occur secondary to pancreatitis

Hepatic artery aneurysm, (a) Left anterior oblique digital subtraction angiogram obtained with the catheter in the distal CHA shows a right hepatic artery branch aneurysm (arrowhead), (b) Digital subtraction completion angiogram shows exclusion of the aneurysm with use of the sac-packing coil embolization technique (arrowhead)

f) Benign Hepatic Cysts :1-Simple cyst2-Polycystic Liver Disease (PLD)3-Hydatid cyst4-Abscess (Pyogenic & Amebic)

1-Simple cyst >>- Def. : fluid filled space having an epithelial lining- U/S :*Anechoic with a well demarcated thin wall & posterior

acoustic enhancement*If complicated with hemorrhage or infection >> internal

echoes & septations , thickened wall or may appear solid *If thick septae or nodules are seen within the cyst >> CT is

recommended as biliary cystadenoma & cystic metastases must be considered in the differential possibilities for complex appearing liver cysts

2-Polycystic Liver Disease (PLD) :-Usually associated with polycystic kidney disease but

may also occur as an isolated finding in a rarer genetically distinct disease

-U/S :*Massive hepatomegaly with innumerable ,

predominantly simple cysts are present

*Portal vein patency should be assessed , compression of the main portal vein may result in portal hypertension as well as associated findings such as splenomegaly and ascites

3-Hydatid cyst :-See before

4-Abscess ( Pyogenic & Amebic ) :-See before

N.B. : Malignant cystic lesions-Biliary cystadenoma / carcinoma-Cystic metastases

g) Hepatic Calcifications :1-Multiple & small :-Tuberculosis , histoplasmosis and less commonly

brucellosis-Usually < 2 cm2-Curvilinear :-Hydatid-Abscess-Calcified (porcelain) GB

3-Localized in a mass :-Metastases-Fibrolamellar HCC-Adenoma4-Sunray spiculation :-Hemangioma-Metastases-Adenoma5-Diffuse increased density :-Hemachromatosis

h) Hepatomegaly :1-Neoplastic :-Metastases-Hepatoma-Lymphoma2-Rasied Venous Pressure :-CHF-Constrictive pericarditis-Tricuspid stenosis-BCS

3-Degenerative :-Cirrhosis (especially alcoholic)-Fatty infiltration4-Myeloproliferaive Disorders :-Polycythaemia rubra vera-Myelofibrosis5-Infective :-Viral (hepatitis , IMN)-Bacterial (abscess , brucellosis)-Protozoal (amoebic abscess , malaria , trypanosomiasis &

kala-azar)

6-Storage Disease :-Amyloid-Hemochromatosis-Gaucher’s Disease-Niemann-Pick disease7-Congenital :-Riedel’s lobe-Polycystic Disease