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Introduction
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1c corpus and 1f fundus (arrow: septum) of gallbladder; 2 gastric antrum (longitudinal scans) |
1 gastric antrum; 2 |
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1 Septated/tortuous infundibulum |
3.4.2. Examination technique and ultrasound (sectional) anatomy
The extrahepatic part of the bile duct system is usually best visualised in section planes parallel to the group of vascular structures of the liver hilum (see 3.1.4.). Placing the patient in the left oblique position and getting him to inspire deeply is the best means of demonstrating the liver hilum in any given patient, since gravity causes the liver, hilum and disturbing gas-containing intestinal structures to move down to the left giving a better acoustic window compared to the simple supine position (which might be sufficient in the slim patient with deep inspiration only). The large intrahepatic bile duct structures will be demonstrated best in the left liver lobe as thin tubular structures parallel to the intrahepatic branches of the portal vein.
The gallbladder is usually visualised best in the left oblique position, with the scanning planes parallel to the given individual anatomy, allowing the operator to meticulously slice all portions of the organ. A second series of sections is routinely necessary at 90° to the first scanning plane in subcostal sections. In these sections the gall bladder will appear as a more or less round to oval structure directly adjacent to the lower surface of the liver. Unlike the more deeply positioned bile ducts, the gall bladder is accessible to direct ultrasound visualized palpation.
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1 common bile duct dilatation due to |
Arrows: less echogenic bile duct calculi; 1
common bile duct; 2 portal vein, arrowhead: intercrossing
hepatic artery |
3.4.3. Pathology (selected)
3.4.3.1 Bile ducts
Occlusion of the bile duct results in an immediate increase in diameter. Ultrasound must not only detect this, but also describe whether the site of occlusion is pancreatic, prepancreatic, or intrahepatic, and ultrasound should reveal the nature of the obstruction, thus allowing rapid progression to further diagnostic and therapeutic maneuvers. It should be noted that in cases where the liver has a high intracapsular pressure such as that secondary to cirrhosis, high-grade fatty or fibrous changes then high intraductular biliary pressures may not lead to an increase in diameter of the intrahepatic biliary radicles. Malignant obstruction, such as suggested by a history of painless jaundice is usually easily distinguishable from obstruction by a stone since the latter can frequently be directly visualised on ultrasound although this depends to some extent on the experience and enthusiasm of the operator.
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1 dilated intrahepatic bile duct branches in 1a segment II and in 1b segment III (“double shot gun sign“); 2 tumour causing obstruction(subcosta scan) |
Aerobilia with highly 1 reflexible gas
bubbles marking the course of common bile duct, suggesting
free bile flow after endoscopic intervention; 2 portal vein
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1 maximum of intrahepatic obstructive bile duct dilatation – suggestive of longtime (many weeks/months) compensated biliary obstruction (subcostal scan) |
1 cholangiocellulary carcinoma (CCC)(cytology) with 2 bile duct occlusion; 3 intercrossing hepatic artery; 4 portal vein; 5 ascites (longitudinal scan) |
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1 complete common bile duct occlusion due to invasive hepatocellulary carcinoma (HCC) (cytology) with thrombus-like intraductal growth; 2 intercrossing hepatic artery 3 portal vein, 4 inferior cava,5 caudate lobe, 6 lymph node 7 diaphragma |
1 bilioduodenal stent with sideholes; 2 distended common bile duct without aerobilia suggestive of stent occlusion; 3 portal vein |
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Common bile duct not detectable due to1portalvarices subsequentlytoportal vein thrombosis; 2inferior cava ,arowhead: right kidney arery |
1 selfexpanding bilioduodenal stent draining semi-sufficiently (no aerobilia) the 2 dilated bile duct |
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Segment III with less marked but significant 1 bile duct dilatation 2 portal vein branch |
Segment III: double shot gun sign with 1 dilated bile duct branch, 2 hepaticarterybranchand 3portalvein branch |
3.4.3.2. Gallbladder
The
main aspects of gallbladder pathology relate to the gallbladder’s
content. Calculi, when asymptomatic, should be considered a finding
only and not a true diagnosis. Their variability in size, number,
and shape can be considerable. Polyps which are greater than 10 mm
in size should lead to consideration of cholecystectomy as there may
be a small risk of these being adenomas instead of the more usual
cholesterol polyps.
Wall-thickening and disturbances of contractility (which can be
determined on ultrasound before and after fatty meal) are indicative
of inflammatory changes: usually chronic when unaccompanied by acute
symptoms and without pain and acute when associated with pain or
discomfort on palpation. Malignant thickening of the wall usually
occurs in very old patients and is always associated with stones.
This should be suspected when associated with infiltration into the
liver tissue. Hydropic enlargement of the gallbladder may be
associated with local (cystic duct) or systemic (bile duct)
obstruction and may be due to benign or malignant causes; it is
mostly not present in malignant jaundice secondary to obstruction
above the cystic duct level (e.g. Klatskin`s tumor).
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Optimum contraction of gallbladder 1a anterior, 1p posterior wall, 1l lumen; 2 gastric antrum |
1 gallbladder impression by 2 cirrhotic liver nodule |
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Numerous calculi, the minor and minute without shadowing |
Small stone with shadowing( arrows) |
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1 polyps - no shadowing in spite of 5-7mm size and no movement after positioning - probably cholesterole-polyps |
Infundibular stone with shadowing (arrows) - impacted since no gravity-depending movement when examed in supine or upright position |
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1 sludge and 2 gall juice in the gallbladder after three days of fasting - fully reversible |
Aerocystia after endoscopic sphincterotomy - calculi will always be at the ground (according gravitation in the given patient`s positioning) |
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1 Sludge-pseudomembrane after successful antibiotic treatment, vanishing spontaneously |
Acute cholecystitis (concardance with clinical findings: pain with directly visualized palpation) - note 1 the multilayered inflammatory swelling of the gallbladder wall. |
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1 calculus 2 sludge 3 liver; no pain under ultrasound controlled palpation - only chronical inflammation with wall thickening* or malignant liver infiltration of gallbladder carcinoma (ultrasound controlled fine needle cytology: no malignancy) |
Bizzar sludge/microlithiasis formation (in a case of acute A hepatitis) |
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No pain under ultrasound controlled palpation – chronical inflammation of the gallbladder with 1 wall thickening; 2 lymphnode, 3 inferior V.cava, 4 right renal vein 5 diaphragma 6 portal vein 7 intercrosing hepatic artery 8 liver |
No gallbladder but 1 hematoma /seroma /inflammation two days after cholecyst-ectomy, 2 liver, 3 portal vein |
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1 HCC (confirmed by ultrasound guided fine needle puncture cytology) 1i invadingi the 2 gallbladder, 3 liver |
3.5. Liver
3.5.1.Gross (macroscopic) anatomy
This the biggest organ in the body is anatomically divided into the larger right and smaller left lobe. The latter harbours the falciform ligament. The right liver lobe is macroscopically subdivided into the uncinate (dorsocaudal) and the caudate (ventrocaudal) lobe, which is typically disproportionately enlarged in cirrhosis. The normal sponge-like consistency of the organ is due to the high content of fluid – blood and bile - , which circulates in four types of tubular structures, three of them (portal vein, bile duct, and hepatic artery) together in Glisson`s triad, the fourth type (the draining hepatic veins) taking a typical course from the hepatic segments towards the inferior vena cava into the three main hepatic veins.The margins of the normal liver are sharp particularly in the left lobe whilst the lower surface is concave (especially in the right lobe).
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Lower surface of liver: 1 vena cava, 2 portal vein, 3 hepatic artery, 4 DHC, 5 caudate lobe of liver, 6 quadrate lobe of liver; impressions are cadaver fixation artifacts only ! |
Upper surface of liver: 1 vena cava, 2 falciform ligament |
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Lateral view of liver: 1 vena cava, 2 portal vein |
“Exploded” view of segmental liver anatomy: 1 vena cava, 2 portal vein |
3.5.2.Examination technique and ultrasound (sectional) anatomy
Subcostal sections in deep inspiration with the probe angulated steeply upwards are best used to examine the liver as a whole. In addition, a second series of scanning planes should be added with the patient in the left oblique position and in deep inspiration. Sections should be taken from an intercostal postion as well as from a subcostal area and supplemented by respiratory maneuvers by the patient as well.
Size and volume of the liver are hardly to measure precisely, since it is not covered by one ultrasound section only. The liver margins, however, are easily demonstrated in longitudinal sections with sharp margins indicating a normal liver volume. Round margins and a convexity to the lower surface suggest an increase in the volume-to-surface ratio. The true borderline between the left and the right liver lobe cannot be demonstrated on ultrasound directly but is in a plane between the inferior vena cava and the gallbladder. The segmental anatomy may be studied by following the branching of the vascular anatomy.
The consistency of the liver should be evaluated by direct palpation under ultrasound visualization and by observing the left lobe being more or less compressed by the pulsation of the right side of the heart (which is separated from the liver by the thin diaphragmatic layer only).
Aside from general questions concerning position and shape of the liver and its overall reflexibility pattern, attention should be given to the vascular architecture particularly with respect to the normal or the disturbed branching and the vessel diameter, as well as to focal lesions of the liver.
3.5.3. Pathology (selected)
A pattern of enhanced reflexibility is suggestive of fatty liver change (although histologigal findings may give a different result; the discrimination of a severe fatty liver only from a true fatty cirrhosis is not a matter of ultrasound imaging, but rather a case for the pathologist). As a rule, the reflex pattern of the liver should be slightly brighter as compared to the adjacent kidney reflex pattern. The enhancement may be spotty, indicating a non-homogenous distribution of fat. These areas are usually geometric and adjacent to venous structures, so they will not be mistaken for true focal lesions.
Focal parenchymal liver lesions are usually round space occupying lesions
and the crucial question as to whether they are benign or not is usually solved by the ultrasound appearance taken in conjunction with a variety of clinical data (history, physical examination, laboratory findings etc). As a rule, benign lesions are clearly defined from surrounding liver tissue by the lack of any infiltration. They rarely become confluent, and they do not disrupt, block or or infiltrate vascular structures (which tends to occur with most malignant lesions). Ultrasound is superior to CT scanning in the detection and depiction of nearly all types of focal lesions of the liver - additional information from abdominal CT-scanning in any given case is usually minimal, and it rarely influences further management.
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Septated congenital cyst (no echinococcus) in segment VII; 1 inferior V.cava |
1 typical echinococcus cysticus: left liver lobe with 1a daughter cysts; 2 liver |
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1 cyst with lessened attenuation posterior resulting in relative brighter “positive shadowing“; 2 gallbladder; 3 “diaphragma“; 4 shadow-artefacts at the margins of cystic structures |
Fine needle evacuation therapy in a symptomatic cyst 1 tip-artefact of fine needle |
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1 typical hemangioma (unchanged in 25 years ultrasound observation) |
1 cystic/solid formation - fine needle aspiration: abscess |
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Focal lesion unchanged for five years - considered as adenoma (confirmed by ultrasound guided fine needle aspiration cytology) |
Highly reflective areas (arrow)with pulsatile movement - portal gas flushing into the liver in intestinal loop bacterial necrosis; 1 gallbladder |
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1 small HCC invading 2 hepatic vein |
Focal nodular hyperplasia - rich vascularisation (power mode), unchanged in size and shape for several years; segment III |
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Multiple focal lesions suggestive of diffuse metastatic disease |
1 HCC (confirmed by ultrasound-guided fine needle aspiration cytology); hyper- vascularisation (power mode, small picture down right) |
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Cystic focal lesions - colour reveals high-volume perfusion typical for Osler`s disease in the liver; 1 pleural effusion; 2 gallbladder; 3 middle hepatic vein |
Multiple focal lesions suggestive of diffuse metastatic disease; arrow: tip of fine needle, precise aspiration biopsy,cytology: malignant cells |
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Irregular 1 fatty- and 2 non-fatty (less fatty) infiltration |
Suspicion of fatty liver disease - note high reflexibility of liver tissue compared with 1 kidney ; 2 less fatty area infiltration-areas |
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Cirrhosis with 1 ascitic fluid and 2 destroyed vascular architecture and completely irregular echopattern |
Cirrhosis with 1 nodular surface, best visible at highly impedant interfaces between 2 gall-juice and liver tissue; note distroyed vascular architecture |
This Part III out of four is to be concluded with some considerations on what is called “normal values” of size and volume.
Measurements should be performed perpendicular to the longitudinal axis of the organ. If this is not possible eg in the liver, then measurement has an even the more limited usefulness. Variations in functional organs must also be taken into consideration so that no “normal values” are given for the great venous vessels which vary with respiration and body position.
Tall individuals have big organs, small persons have small abdominal organs. In addition, great variations according to the individual`s age are normal, e.g. in the spleen volume (high in the young, smaller in the adult).
Abdominal aorta 2 cm (diameter).
Pancreas head < 3 cm,
body < 2 cm,
main pancreatic duct: 2 mm.
Common bile duct < 6 mm (prepancreatic) but < 8 (11 mm) in the old.
Intrahepatic bile ducts < 2 mm.
Gallbladder < 8 (11) cm x 4 (5) cm.
Spleen < 11 cm x 7 cm x 5 cm (larger in the young).
Kidney 11 cm x 4 (6) cm
For the experienced ultrasonographer, the aspects of the given (sono-) morphology are as a rule much more important than pseudo-accurate measurements.