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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5795_Библиотеки_им_академика_М_И_Перельмана.pdf
13 Upper Abdominal US inNeonates, Infants andChildren: (Excluding the Kidneys)
Fig. 13.4 Liver vessels: (a) Hepatic veins, bidirectional undulating ow demonstrated by CDS
(either red or blue signals indicating two ow directions during respiratory cycle) with cardiac and
respiratory modulation also demonstrated by spectral ow analysis. (b) Main portal vein entering
liver: note no signicant variation in diameter. (c) Portal vein ow on CDS (red colour signals):
note adjacent hepatic artery with faster ow in same direction (coded in orange). (d) DuplexDoppler ow prole conrms normal hepatopetal portal ow, +1 indicates maximum velocity
269
Hepatic Artery (HA)
• Less often important.
• Systolic velocity varies with age and nutritional status (Table 13.2b), as does
diastolic velocity/RI.
• CDS essential for differentiating particularly peripheral branches from biliary
structures and for proper angle correction (if ow velocity measurements taken).
Note HA shows same ow direction as portal vein—only by selecting proper CDS
settings (gate, lter, ow velocity)—discrimination of PV and HA feasible on CDS.
13.3.3.10 Special Aspects ofNewborns andInfants
• After closure of ductus venosus—relative increase in size of the right liver
lobe—neonates have signicantly larger left liver lobe than older children. Left
and right liver lobes may even be similar in size.
• Newborns’ liver softer and more exible—slightly rounded lower margin is
physiologic.
• Parenchyma less differentiated and less echogenic than in older age due to
reduced brosis and less fat—compared to renal cortex liver parenchyma echo-
genicity is lower.
• Periportal echoes less prominent.
• Ductus venosus can remain patent up to some weeks—seen as tubular vascular
structure coursing from ectatic section of left PV to ICV/right atrium. Closes
270
a
a
? (85±15)
? (60±10)
a
a
M. Riccabona
(a) Normal ow in portal vein
Rule of thumb: above 20cm/s in non-fasting child (general lower cut-off value):
With some respiratory undulation
Flow pattern and—to a lesser degree—ow velocities inuenced by respiration:
Table 13.2 Normal values for liver vessel ow
More undulating ow in earlier years than later in childhood.
In healthy term neonates peak portal blood ow may double 15min after feeding:
Fasted=24±1.3cm/s after feeding=35.9±2.4cm/s
0–5 3.5±2 9.1± 70 ?
(b) Age-dependent ow velocities in hepatic artery
Age (years) PV diameter (mm) PV velocity (cm/s) PV ow (mL/min) HA velocity (cm/s) HA RI (%)
6–12 6.3±2 13.4± 250 ? (50–100)
>12 7±2.6 14.6±5 380 70–120 60±4
No established normal values—the numbers given for orientation are from individual reports and own experience, particularly in neonates
Average values are not applicable, as velocities are very low in neonates (around 40cm/s), even lower in preterm babies, and increase relatively quickly to
values similar to older children—HA hepatic artery, PV portal vein
(c) Hepatic vein ow prole
Schematic drawing of typical ow patterns of hepatic veins (Types I–IV), and how elasticity index (EI) is calculated (EI=a/b %), (d) typical ow patterns
a
of hepatic veins
Type III Dampened Monodirectional, but still modulated ow EI~40%
Type II Unspecic Triphasic, monodirectional ow EI~90%
Type I Normal Triphasic, bidirectional ow EI~120%
Type IV Severely impaired Monodirectional, uniform, unmodulated ow EI~0%
13 Upper Abdominal US inNeonates, Infants andChildren: (Excluding the Kidneys)
271
spontaneously—then seen as echogenic band (=ligamentum venosum in later
age) (see Fig.13.2a, b).
• Unusual or altered ow patterns in neonates do not always indicate hepatic dis-
ease; often reect physiologic systemic or vascular variations (e.g. patent fora-
men ovale, PDA, persistent ductus venosus Arantii). Interpretation of Doppler
ndings needs to be made with care and respect to all other clinical and labora-
tory data as well as imaging ndings; sometimes additional assessment of
abdominal aorta, renal or cerebral vessels, heart and other large vessels neces-
sary for deciding on origin of unusual ow ndings.
13.3.4 Pathology oftheLiver
13.3.4.1 Congenital Changes andNormal Variance
Situs Inversus (Abdominalis)
Definition
Liver on left side, no isolated liver malformation.
US Findings
Liver seen in left upper quadrant, spleen situated in right upper abdomen (potentially with multiple splenunculi—polysplenia syndrome). Liver anatomy is
mirrored.
Butterfly or Midline Liver
Definition
Often associated with other (systemic) malformations and syndromes (e.g.
ambiguous situs, polysplenia syndrome, asplenia, gastroschisis and omphalocele).
US Findings
Buttery shaped liver positioned medially, often hilus structures in unusual position
and relation, more difcult to nd and identify. Left and right liver lobes often of
similar size. HVs drain directly into right atrium or into hemiazygos continuation of
interrupted ICV.
Hypoplasia/Atrophy ofLeft Liver Lobe andOther Variations
Hypoplasia is usually a consequence of intrauterine events—not congenital or
hereditary, mostly only conatal condition.
Other variants are: diaphragmatic bump lled with liver, variations associated
with diaphragmatic hernia and liver up-position, variations associated with gastroschisis and omphaloceles.
Many variations both of arterial and venous anatomy are most identied by
proper technique using CDS.Have little other implication—unless liver surgery or
transplantation planned.
272
M. Riccabona
13.3.4.2 Inflammatory Conditions
Hepatitis
Definition
Mostly viral in origin. May occur in any time of childhood, even neonatally. Shows
large variance in its course and outcome.
During its course there may be brosis, other diffuse hepatopathies, enlargement
or shrinkage, eventually cirrhosis (with increased tunmour risk) or secondary
abscess formations.
US Findings
Unspecic—liver normal or slightly enlarged. Usually surface remains smooth,
lower margin slightly rounded. Echogenicity more or less decreased, with normal
appearance of periportal area, unless signicant decrease in parenchymal echogenicity—then periportal regions become prominent. Associated oedematous
changes of gall bladder wall and bed possible (DDx: cholecystitis, congestive, vasculitis such as Kawasaki disease, during intensive care).
Associated ndings: enlarged lymph nodes in hepato-duodenal ligament,
splenomegaly.
CDS
Hyperaemia with low RI of HA, potentially increased PV ow; in severe enlargement and thus increase in liver resistance also reduced undulation in HV.
Note US does not allow denition of aetiology or discrimination between viral,
bacterial, toxic, drug induced or other forms of hepatitis/hepatopathies. Mimics exist.
Liver Abscess
Definition
Usually haematogenous, sometimes ascending through bile ducts.
Various entities—bacterial, fungus, secondary after malignant inltration,
echinococcal or other parasites (amoebiasis, ascariasis, schistosomiasis, etc.).
US Findings
Spherical or polygonal focal alteration of liver texture. If necrotic—central
hypoechoic, sometimes with (oating) echoes, in complex abscess formations
increased central echogenicity, uid levels. Usually peripheral membrane and halolike peripheral hypoechogenicity (Fig.13.5).
Image varies with course—only subtle ndings in beginning, more pronounced
in later stage.
Other focal liver lesions sometimes difcult to differentiate (metastasis and
inltration in systemic haematologic disease).
CDS
Shows central avascular nature with peripheral membrane-like hypervascularisation
and hyperaemia. Reactive diffuse hyperaemia of HA and PV.
13 Upper Abdominal US inNeonates, Infants andChildren: (Excluding the Kidneys)
Fig. 13.5 Liver abscess. (a) Focal nodular hypoechoic disruption of liver parenchyma and several
initial small lesions—in this case fungal septicaemia in oncology patient during chemotherapy
(fungal abscess). (b) CDS may conrm the necrotic avascular nature and show peripheral,
membrane- like hypervascularisation
273
If associated with ascending condition, gas or air bubbles seen in peripheral bile
ducts—causing small echoes with reverberation and twinkling on CDS (aerobilia).
Spectral trace shows blip-like short high-amplitude partially bidirectional signals.
Sometimes difcult or impossible to distinguish from intravenous portal gas.
Special Entities
• Echinococcal/hydatid disease: manifest as cystic liver lesions; different appear-
ances depending on age and stage (Types I–IV, Gharbi classication used most
commonly) (Table13.3) (Fig.13.6). In children Types I and III commonly seen
(younger manifestation). Differentiation of Type I lesion from other hepatic cysts
difcult. US used for puncture and therapeutic alcohol/drug instillation.
• Other causes of abscess: fungus, amoebiasis, ascariasis and schistosomiasis.
Appearance unspecic—with more or less target appearance; sometimes linear
echogenic structures demonstrated with ascariasis, or echogenic portal tracts
with hepatomegaly in schistosomiasis, may aid diagnosis.
Table 13.3 Hydatid disease—grading system (Gharbi classication)
Type I: Pure simple cystic uid collection
Type II: Cystiform uid collection with split, nodular-irregular wall; may contain echoes in
central compartment
Type III: Cyst with complex uid collection and internal septae
Type IV: Cyst with heterogenous echo pattern, potentially beginning calcications
Type V: Cyst with reecting thick walls (mature/old form), often has calcied walls
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 nonspecic: diagnosis made by laboratory nding, history and potentially
ne needle aspiration/biopsy. Similar appearance seen in tuberculosis, sarcoidosis,
274
M. Riccabona
ab
c
Fig. 13.6 Echinococcus: (a) Two hydatid cysts with complex inhomogenous content (stages 3–4).
(b) Extended view delineates huge hydatid cyst with slightly complex uid and septations in left
liver lobe (stage 3) (c) Another huge hydatid cyst (stage 3) demonstrating the large variation in
imaging appearance
metastatic disease, lymphoma or in patients with (acquired) immune-deciency
syndromes (the latter often with very mixed liver manifestation).
Role ofUS
• Nonspecic in inammatory 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 pre-
existing or causative conditions always essential.
• Role of US elastography in these conditions and in childhood yet undened.
13.3.4.3 Other Parenchymal Liver Disease
Definition
Nonspecic 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).
13 Upper Abdominal US inNeonates, Infants andChildren: (Excluding the Kidneys)
275
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
Definition
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.
US Findings
• Large liver, maintained smooth surface, but lower margin rounded.
• Echogenicity increases, structure commonly remains homogenous—focal stea-
totic areas usually occur along PV branches, but also elsewhere; inhomogenous
steatosis possible, as well as areas of non-steatosis (Fig.13.7a).
• Due to high attenuation, there is decreased penetration of sound, increasing sig-
nal loss and noise in deeper compartments. Sound attenuation used for grading
severity of steatosis.
• Potentially poor HV visibility.
• Role of US elastography and new tools for fat quantication yet undened in
childhood.
Note Focal non-steatotic areas of normal tissue appear like focal liver lesions in
fatty liver (Fig.13.7b, 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).
Fig. 13.7 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
276
M. Riccabona
Liver Congestion
Definition
Occurs in conditions with increased right atrial pressure (secondary to congenital
cardiac malformations, other cardiac disease, chronic respiratory insufciency with
increased intrapulmonary pressure such as cystic 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 shows reduced or lack of size modulation.
• Ascites, splenomegaly, omental thickening and oedematous thickening of con-
gested bowel wall—secondary signs.
• IVC (and often LV, too) usually enlarged with reduced change in calibre during
respiratory and cardiac cycle.
• May show low stiffness values on US elastography in acute and increased maxi-
mum shear wave velocities (due to secondary brosis) in chronic phase.
CDS
Pronounced ow undulations triggered by atrial contractions seen into liver periphery.
Particularly seen secondary to tricuspid valve insufciency. 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.
Liver Fibrosis
Definition
Either congenital genetic condition (e.g. ARPKD—“ciliopathies”) or consequence of
chronic conditions (e.g., cholestatic/inammatory). 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 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 brotic
areas may produce a “starry sky” appearance of the liver (Fig.13.8).
Cirrhotic Liver
Definition
Main reasons in childhood: bile duct hypo-/aplasia, extrahepatic bile duct stenosis,
α1-antitrypsin deciency, various metabolic diseases (Wilson disease,
13 Upper Abdominal US inNeonates, Infants andChildren: (Excluding the Kidneys)
Fig. 13.8 Liver brosis—“starry sky”
appearance. Strikingly increased periportal eld
echogenicity with irregular structure from biliary
brosis
277
Fig. 13.9 Liver cirrhosis: (a) Diffusely altered echogenicity in a patient with alpha-1 antitrypsin
deciency. (b) Hypertrophy of caudate lobe in cirrhosis. (c) Severe macronodular cirrhosis in an
adolescent with cystic brosis and biliary cirrhosis. (d) Micronodular alteration of liver parenchyma in a neonate with tyrosinaemia—indicating early liver cirrhosis. (e) Irregularly shaped liver
surface and ascites in severe liver cirrhosis in an adolescent awaiting liver transplantation
tyrosinaemia, cystic brosis, etc.), chronic intoxication (e.g. copper), drug induced,
after (chronic) hepatitis/chronic inammatory disease, liver brosis/choledochal
cysts, Caroli syndrome and other ciliopathies.
US Findings
Several states during course of disease (Fig.13.9):
• Initially increasing size, no other specic 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.
278
M. Riccabona
• Caudate lobe commonly spared—develops compensatory hypertrophy, becom-
ing spherical and of lower echogenicity (Fig.13.9b).
• 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 ndings associated with portal
hypertension.
• Increased stiffness with high maximum shear wave velocities on US elastogra-
phy, may be also patchy and inhomogenous (Fig.13.9f).
CDS
Essential for showing portal hypertension (see below)—usually intrahepatic form in
cirrhosis.
• Extrahepatic dilatation of PV with tapering at hilus as well as rareed intrahe-
patic PV branches.
• Secondary compensatory hypertrophy of HA which becomes large and very
pulsatile.
• Increased arterial perfusion secondary to reduced portal venous ow.
Liver Involvement inSystemic 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 ow and reduced undulations of HV ow prole.
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 brosis and
biliary cirrhosis, multiple intrahepatic + common bile duct + gall bladder bile
stones/calcications, ascending cholangitis (Fig.13.9c).
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) (Fig.13.9d).