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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5790_Библиотеки_им_академика_М_И_Перельмана.pdf
7.3 Pathology of the Liver
225
• Other causes of abscess: fungus, amoebiasis, ascariasis and schistosomiasis.
Appearance unspecifi c – with more or less target appearance; sometimes linear
echogenic structures demonstrated with ascariasis, or echogenic portal tracts
with hepatomegaly in schistosomiasis, may aid diagnosis
7.3.2.3 Granulomatous Disease
Manifests as single or multiple hypoechoic lesion, usually representing granuloma
(potentially secondary abscess formation). Similar appearance as cat scratch disease
(or focal lymphoma).
US nonspecifi c: diagnosis made by laboratory fi nding, history and potentially
fi ne needle aspiration/biopsy. Similar appearance seen in tuberculosis, sarcoidosis,
metastatic disease, lymphoma or in patients with (acquired) immune defi ciency
syndromes (the latter often with very mixed liver manifestation).
7.3.2.4 Role of US
• Nonspecifi c in infl ammatory liver conditions
• May be useful initially for narrowing down DDx or excluding other conditions
that may cause similar symptoms
• Used for follow-up, particularly in chronic conditions
• Used for guided diagnostic punctures/therapeutic drainage/drug instillation
• Additional clinical and historical data, serologic diagnoses or search for preexisting or causative conditions always essential
7.3.3 Other Parenchymal Liver Disease
7.3.3.1 Hepatopathy
Defi nition
Nonspecifi c fi nding, seen in a number of conditions such as secondary to drugs and
treatment (drug induced/toxic damage) or secondary to systemic or metabolic disease. May be restricted to liver (e.g., Wilson disease, Gilbert syndrome) or systemic
(e.g., glycogen storage disease, tyrosinaemia).
US Findings
Liver usually slightly enlarged with slightly increased echogenicity, may have some
inhomogenicity of parenchyma with a more or less nodular pattern, without interruption of normal straight and smooth vascular architecture.
Fatty Liver/Steatosis
Defi nition
Rare in early childhood – mostly secondary to pre-existing liver condition or liver
damage.
Increasingly observed in adolescence due to obesity.
Secondary to other systemic disease/treatment or drug induced.
226
abc
Fig. 7.7 Steatosis (focal, non-steatosis, etc.): ( a ) Focally increased echogenicity without disrup-
tion of contour or structure, in focal liver steatosis. ( b , c ) Fatty liver with increased echogenicity,
focal darker non-steatosis area with consequently regional normal liver echogenicity
7 Liver and Bile System
US Findings
• Large liver, maintained smooth surface, but lower margin rounded
• Echogenicity increases, structure commonly remains homogenous – focal steatotic areas usually occur along PV branches, but also elsewhere; inhomogenous
steatosis possible, as well as areas of non-steatosis (Fig. 7.7a )
• Due to high attenuation, there is decreased penetration of sound, increasing signal loss and noise in deeper compartments. Sound attenuation used for grading
severity of steatosis
• Potentially poor HV visibility
NOTE : Focal non-steatotic areas of normal tissue appear like focal liver lesions in
fatty liver (Fig.
7.7b, c ). Commonly of lower echogenicity, spherical or polygonal
shape, often in segment IV – do not show any change of contour or alter course of
vessels, which helps for DDx. Occasionally regional adenomatous hypertrophy of
normal liver may occur (particularly in children after chemotherapy, who also may
develop liver adenoma).
Liver Congestion
Defi nition
Occurs in conditions with increased right atrial pressure (secondary to congenital
cardiac malformations, other cardiac disease, chronic respiratory insuffi ciency with
increased intrapulmonary pressure such as cystic fi brosis), and secondary to intensive
care with volume overload and increased right atrial pressure.
US Findings
• Enlarged liver, initially reduced echogenicity
• In longer duration/chronic state – increased echogenicity
• Smooth surface, rounded lower margin, dilated HV that can be followed into
liver periphery and showes reduced or lack of size modulation
• Ascites, splenomegaly, omental thickening and oedematous thickening of con-
gested bowel wall – secondary signs
7.3 Pathology of the Liver
227
• IVC (and often LV, too) usually enlarged with reduced change in calibre during
respiratory and cardiac cycle
CDS
Pronounced fl ow undulations triggered by atrial contractions seen into liver periphery. Particularly seen secondary to tricuspid valve insuffi ciency. Reduced respiratory modulation, similar phenomena seen in IVC. Depicted and documented by
CDS, but lack of diameter change during respiratory and cardiac cycle nicely documented by M-Mode.
7.3.3.2 Liver Fibrosis
Defi nition
Either congenital genetic condition (e.g. ARPKD) or consequence of chronic conditions (cholestatic/infl ammatory). Rarely isolated entity or disease.
US Findings
• Initial/mild manifestation – not visible
• With increasing severity and duration – increasing echogenicity of periportal
areas with narrowed and potentially irregularly shaped peripheral PV branches –
HV stays normal
• Increased vascular resistance, increased size of HA – eventually leading to bili-
ary cirrhosis and portal hypertension with all its fi ndings (see below)
• In underlying bile duct conditions respective changes seen (e.g. irregularity or
dilatation of peripheral bile ducts). The very bright echoes of periportal fi brotic
areas may produce a “starry sky” appearance of the liver (Fig. 7.8 ).
7.3.3.3 Cirrhotic Liver
Defi nition
Main reasons in childhood: bile duct hypo-/aplasia, extrahepatic bile duct stenosis, α1-antitrypsin defi ciency, various metabolic diseases (Wilson disease, tyrosinaemia, cystic fi brosis, etc.), chronic intoxication (e.g. copper), drug induced,
after hepatitis, liver fi brosis/choledochal cysts, Caroli syndrome and other
ciliopathies.
Fig. 7.8 Liver fi brosis – “starry sky” appearance.
Strikingly increased periportal fi eld echogenicity
with irregular structure from biliary fi brosis
228
a
bc
7 Liver and Bile System
de
Fig. 7.9 Liver cirrhosis: ( a ) Diffusely altered echogenicity in a patient with alpha-1 antitrypsin
defi ciency. ( b ) Hypertrophy of caudate lobe in cirrhosis. ( c ) Severe macronodular cirrhosis in an
adolescent with cystic fi brosis and biliary cirrhosis. ( d ) Micronodular alteration of liver paren-
chyma in a neonate with thyrosinaemia - indicating early liver cirrhosis. ( e ) Irregularly shaped liver
surface and ascites in severe liver cirrhosis in an adolescent awaiting liver transplantation
US Findings
Several states during course of disease (Fig. 7.9 ):
• Initially increasing size, no other specifi c fi ndings
• Then decrease of liver size. Irregular surface (varies with macro- and micronodu-
lar forms), convex shape of very sharp lower margin, increased inhomogenous
echogenicity with reduced sound penetration, patchy parenchymal structure with
focal nodular regeneration
• Caudate lobe commonly spared – develops compensatory hypertrophy, becom-
ing spherical and of lower echogenicity (See Fig. 7.9b )
• HV and eventually PV become tapered, narrowed and intrahepatically dimin-
ished – with irregular course and margins
• Secondary chronic changes: decreased size of gall bladder with thickened wall,
splenomegaly, ascites and other fi ndings associated with portal hypertension
CDS
Essential for showing portal hypertension (see below) – usually intrahepatic form in
cirrhosis. Extrahepatic dilatation of PV with tapering at hilus as well as rarefi ed
intrahepatic PV branches. Secondary compensatory hypertrophy of HA which
becomes large and very pulsatile. Increased arterial perfusion secondary to reduced
portal venous fl ow.
7.3 Pathology of the Liver
229
7.3.3.4 Liver Involvement in Systemic Disease
Many systemic diseases may affect liver, causing hepatomegaly and eventually cirrhosis (e.g. Niemann-Pick disease). All conditions with severe parenchymal damage develop high-arterial RI secondary to increased peripheral liver resistance
associated with reduced PV fl ow and reduced undulations of HV fl ow profi le.
NOTE : In most of these conditions, secondary malignant transformation and mani-
festation of liver carcinoma quite common – regular monitoring advisable. Nodular
regeneration occurs in most of these conditions (cannot be clearly differentiated
from other focal lesions such as adenoma or liver carcinoma by conventional US).
Additional serologic parameters (e.g. α1-fetoprotein), IV-ce-US, dynamic CT/MR
imaging or US-guided biopsy often necessary:
Cystic fibrosis
Causes cholestasis, both intra- and extrahepatically, with secondary fi brosis and
biliary cirrhosis, multiple intrahepatic + common bile duct + gall bladder bile stones/
calcifi cations, ascending cholangitis (see Fig. 7.9c ).
Glycogen storage disease
Manifestation varies. Pronounced hepatomegaly with relatively normal, homogenous, slightly hyperechoic parenchyma typical, especially for Type I.
Tyrosinaemia
Leads to liver cirrhosis (commonly also renal involvement – enlarged kidneys with
increased echogenicity, distal tubular dilatation + precipitations) (see Fig. 7.9d ).
Wilson disease
Copper storage disorder, leads to haemolytic events and early liver insuffi ciency
with relatively unspecifi c liver changes. Additional neurologic symptoms. US nonspecifi c in early stage, then increased size and echogenicity; cirrhosis develops in
later stages.
α1-antitrypsin deficiency
Most common cause of “hepatitis syndrome” in infancy. US in early phases nonspecifi c, potentially some enlargement + homogenous alteration of texture similar to
hepatitis. Course/severity varies, eventually may lead to liver cirrhosis (see
Fig. 7.9a ).
Haemosiderosis
Iron deposit in liver – either idiopathic or secondary to various systemic/haemolytic
conditions. US nonspecifi c: enlargement, in early phase, smooth surface and
rounded lower margin with increased echogenicity. Over time more nodular parenchymal aspect develops. The further course depends on severity and management of
underlying condition.
230
7 Liver and Bile System
NOTE : Specifi c MR techniques and programmes using susceptibility phenomena
on T2-star-weighted sequences allow (semi-)quantitative assessment of iron content – reliable monitoring during therapy and follow-up.
7.3.3.5 Role of US
Most commonly used imaging modality for diagnosis and follow-up of liver
conditions.
Particularly CDS, ce-US and complementary dynamic sectional imaging (most
commonly MRI) can be helpful – particularly for focal disease.
Increasingly US-elastography also applied to children with liver disease: shear
wave velocities above 18.8 - 2 m/sec seem to be indicative for fi brotic / cirrhotic
changes.
Depending on query (M)ERCP may be indicated in conditions affecting the biliary system.
7.3.4 Portal Hypertension and Vascular Problems
7.3.4.1 Portal Hypertension
Defi nition
Increasing liver resistance with increase of PV pressure above 10 mmHg. Most
common and important vascular liver disease. Pressure measurement not feasible
by US, but indirect signs on gray scale and CDS/spectral analysis enable reliable
assessment in diagnosis and follow-up of suspected portal hypertension. Details of
underlying conditions are in their respective sections.
Causes typically placed into three broad categories:
• Prehepatic: portal vein obstruction/occlusion/thrombosi/stenosis
• Intrahepatic/intra-sinusoidal: parenchymal disease with increased resistance of
the peripheral sinusoid vascular bed (some also place peripheral intraheptic PV
impairment in this group)
• Posthepatic: HV problems, increased intrathoracic/right atrial presssure
US criteria
Findings of underlying condition (e.g. liver fi brosis/cirrhosis, hepatomegaly, periportal fi brosis)
• Commonly hilar PV tapering: enlargement of prehepatic portion, narrower intra-
hepatic portion, except for prehepatic origin
• Secondary splenomegaly with tortuous vessels at splenic hilus
• Portosystemic anastomoses : splenorenal, splenogastric, from spleen to abdomi-
nal and thoracic wall to diaphragmatic vessels/gastric veins with secondary
oesophageal varices, recanalisation of umbilical vein, collateral vessels from
liver hilus to gastric veins, etc. Secondary dilatation of draining venous vascular
system with formation of anastomotic venous networks (abdominal wall around
the umbilicus – “caput medusa”, inferior mesenteric anastomoses to rectoanal
veins with haemorrhoids, tubular enlarged mesenteric veins with congestive
changes of mesentery and bowel wall), secondary ascites
7.3 Pathology of the Liver
abc
Fig. 7.10 Portal hypertension: ( a ) Inverted hepatofugal fl ow in central portal vein encoded in blue
(next to red encoded HA) due to portal hypertension with intrahepatic block. ( b ) Duplex fl ow
analysis confi rms the inverted direction of portal venous fl ow. ( c ) CDS demonstrates lack of fl ow
in central portal vein due to extrahepatic portal vein thrombosis in a patient after liver
transplantation
• PV thrombosis may be primary and causative or secondary to reduced portal fl ow
• Secondary cavernous transformation with development of veins in PV wall
(multiple tubular tortuous small lumen veins at liver hilus without visualisation
of normal PV. Flow usually insuffi cient to prevent portal hypertension. May
reconstitute normal appearing intrahepatic PV
Doppler criteria :
• HV: veins diffi cult to fi nd (CDS helpful), reduced undulation – potentially band-
like fl ow spectrum. Often reduced fl ow, slow velocity
• PV: initially increased undulation, then loss of undulation of PV fl ow. Reduced
fl ow velocities, eventually bidirectional or hepatofugal inverted fl ow direction
(Fig. 7.10 ).
• HA: secondary to reduced PV fl ow, arterial liver perfusion increases. HA
becomes larger, very pulsatile, with high (particularly systolic) velocities
US depiction of portal systemic shunts :
• CDS may directly visualise abnormal venous pathways (e.g. recanalised umbili-
cal vein, varices at gastrooesophageal junction, splenorenal shunts, inverted fl ow
in superior mesenteric vein)
• If no collaterals are seen, fl ow volume measurements of PV, splenic + superior
mesenteric vein may be helpful (indirect sign): PV-volume fl ow should be equal
or higher than sum of volume fl ow of splenic vein + superior mesenteric vein –
otherwise there must be some shunt somewhere
NOTE : These measurements are cumbersome in small children, heavily rely on
good angle correction at reasonable Doppler angles as well as accurate crosssectional assessment of vessel diameter. Due to underlying equation even mild
errors in vessel area/diameter measurements cause enormous changes in calculated
volume fl ow (see Chap. 1 , Doppler US)
In portal vein thrombosis /prehepatic block: lack of visualisation of PV fl ow
(Fig. 7.10c ) – recanalisation or cavernous transformation can also be assessed.
NOTE : Thrombi can reach into splenic or superior mesenteric vein – these vessels
always need to be assessed for patency or involvement.
231
232
abc d
Fig. 7.11 Posttraumatic AVF in liver, other vascular liver malformations: ( a ) CDS reveals high-
velocity turbulent fl ow in a posttraumatic arteriovenous fi stula. ( b ) Duplex trace analysis confi rms
low resistance arterial fl ow in the feeding artery and arterialised fl ow in draining vein. ( c ) Portal
vein aneurysm after liver transplantation at site of anastomosis. ( d ) CDS reveals turbulent fl ow in
the aneurysm
7 Liver and Bile System
7.3.4.2 Vascular Malformations
Intrahepatic vascular malformations or other pathology are rare. Many normal
variants.
May be idiopathic/congenital, secondary after trauma/surgery/transplantation,
in/after infl ammation (e.g. mycotic or infl ammatory aneurysm), or connected with
systemic vascular disease (Kawasaki, ADPKD Type I, fi bromuscular dysplasia,
etc.).
• Arteriovenous/arterioportal shunts/fi stula: vary in size, (multi)focal or even dif-
fusely generalised
• Postoperative or posttraumatic fi stula: usually only seen on CDS, shunt fl ow
assessed by spectral analysis of feeding and draining vessel(s)
• Aneurysms: ectatic cyst-like vessel changes – use CDS, turbulent fl ow, alternat-
ing bidirectional fl ow jet, may (partially) thrombose (Fig. 7.11c, d )
• Haemangioma/haemoendothelioma see below under liver tumours
US and CDS fi ndings
Depend on entity and size (Fig. 7.11 ).
In shunts, CDS may enable depiction of arteriovenous fi stula and visualise
hyperperfusion of feeding vessel with secondary arterialisation of draining vein
(PV, HV) (Fig. 7.11a, b ). PV shunts rare and diffi cult to fi nd.
7.3.4.3 Portal vein and hepatic artery stenosis
Extremely rare in childhood, same conditions and features/criteria as in other vessels apply. More common after transplantation or surgery.
US and CDS fi ndings :
• Change in diameter
• Regional fl ow turbulence with aliasing
• Pre- and poststenotic fl ow pattern alteration with delayed systolic upstroke, long
acceleration time (pulsus tardus et parvus)
• Turbulent diastolic fl ow
• Turbulence and increased velocity at site of stenosis…
NOTE :All fi ndings depend on severity and grade of stenosis.
7.3 Pathology of the Liver
ab
Fig. 7.12 Abernethy malformation: ( a ) Huge nodular liver structural alteration (+ +) in a 9-year-
old girl with Abernethy malformation – likely to present an FNH. ( b ) CDS of liver hilus vessels
demonstrates lack of a normal portal vein entering the liver. The splenic and mesenteric veins drain
into an unusual venous connection to the inferior vena cava (coded in blue ). The more orange
coded vessel is the reactively enlarged hepatic artery
7.3.4.4 Congenital Agenesis or Variants of Portal Vein/Congenital
Portocaval Anastomosis/Abernethy Malformations
Variety of conditions, extremely rare - lead to liver failure/fi brosis.
US and CDS fi ndings :
• Non-visualisation of portal vein (Fig. 7.12 )
• Anomalous vessels connecting splanchnic veins to central circulation
• Resultant arterial hyperperfusion to compensate for lack of PV perfusion. Often
develop FNH and/or adenomas, may have malignant course
233
7.3.4.5 Hepatic vein thrombosis/occlusion/stenosis
Summarises variety of conditions, most typical ones:
Budd-Chiari syndrome
Large veins obstructed/occluded by space occupying lesion compressing the vessel
or by thrombosis.
Veno-occlusive disease (VOD)
Sinusoidal obstruction syndrome: affects small peripheral portions - obstruction and
thrombosis/fi brosis of small sinusoidal venoles after necrosis of hepatocytes due to
sinusoidal injury/disease. Typically a complication after chemotherapy or radiation
for bone marrow transplantation, particularly after Wilms’ tumour.
Increased right atrial/intrathoracic pressure
Secondary to cardiothoracic conditions.
NOTE : The loss of typical HV fl ow modulation is very sensitive for veno- occlusive
disease, but not specifi c. Any other cause that either increases hepatic resistance and
stiffness or elevates right atrial pressure will cause similar phenomena. However,
HV spectral analysis helpful for follow-up to document improvement and recovery
by demonstrating increasingly normal fl ow patterns during treatment.
234
7 Liver and Bile System
7.3.4.6 Portosystemic Shunts
Secondary to portal hypertension or vascular malformation/anomaly (see above).
Surgically introduced shunts – for treatment of portal hypertension, including TIPS.
CDS used to assess patency of shunts; spectral analysis after proper angle correction allows quantifi cation; helpful for follow-up and reveals complications such as
occlusion, thrombosis, or stenosis.
Persistent ductus venosus also causes shunting between the left PV and systemic
venous circulation.
• Shunt direction and fl ow velocity can be measured (see Fig. 7.2a, b ). A persisting
venous duct is usually sign for underlying liver disease and rarely a vascular
problem itself.
7.3.5 Liver Trauma
Liver laceration or contusion is relatively common in paediatric blunt abdominal
trauma. However, early after trauma, even severe injuries are easily missed by US
due to similar echogenicity of fresh blood and liver parenchyma – follow-up after
12–24 h is essential. Therapy and prognosis as well as risk of complications depends
on grade, thus also US should try to establish a grading (Table 7.4 )
Table 7.4 Liver injury grading system
Grade I
Haematoma: subcapsular, <10 % surface area
Laceration: capsular tear, <1 cm depth
Grade II
Haematoma: sub capsular, 10–50 % surface area
Haematoma: intraparenchymal, <10 cm diameter
Laceration: capsular tear, 1–3 cm depth, <10 cm length
Grade III
Haematoma: sub capsular, >50 % surface area or ruptured with active bleeding
Haematoma: intraparenchymal, >10 cm diameter
Laceration: capsular tear, >3 cm depth
Grade IV
Haematoma: ruptured intraparenchymal with active bleeding
Laceration: parenchymal disruption involving 25–75 % hepatic lobes or
1–3 Couinaud segments (within one lobe)
Grade V
Laceration: parenchymal disruption involving >75 % hepatic lobe
>3 Couinaud segments (within one lobe)
Vascular: juxtahepatic venous injuries (IVC, major hepatic vein)
Grade VI
Vascular, hepatic avulsion
Adapted from American Association for Surgery of Trauma