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Lucas Greiner Wuppertal/Germany

Lucas Greiner, MD Professor of Internal Medicine Director, Medical Clinic 2 Helios-Clinics University Witten/Herdecke Heusnerstr. 40 D – 42283 Wuppertal [email protected]

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9HVVHOV The aorta and inferior vena cava are visible in every patient (the latter sometimes following a Valsalva‘ s maneuver only). They are landmarks in abdominal ultrasound; whenever orientation is lost, one should return to these well known and easily identifiable organs. This is also true for the vascular structures of the liver hilum. Therefore, knowledge of anatomy of the great vessels including their main branches is indispensible (for more details, see also Part I; Arab J G Vol 2, No 2, October 2001, 358371). $RUWDFHOLDFD[LVVXSHULRU PHVHQWHULFDUWHU\DQGUHQDODUWHULHV The abdominal Aorta is characterized by its position, pulsations and by the typical branching of the celiac axis, superior mesenteric artery and the iliac arteries (positioned ventral to the concomitant veins). In longitudinal sections, the aorta-slices are band shaped with more or less well seen main branches of the celiac axis and the superior mesenteric artery in the upper abdomen. The angle between these two branches encompases the portion of the pancreas which is scanned transverse to the organ axis. In transverse sections, where the aorta is seen as a circular structure, the celiac axis looks like a double hooked structure (the right portion representing

the hepatic artery, the left portion the splenic artery). The renal arteries are positioned dorsal to the renal veins with the right renal artery crossing under the inferior vena cava. &DYDLQIHULRULOLDFUHQDODQG KHSDWLFYHLQV The inferior vena cava is at the same level in the body as the aorta and parallels its course on the right down to the iliac bifurcation. The inferior vena cava may be visible only in deep inspiration or in right heart failure. It shows typical double-pulsatory movements in healthy people. Easily demonstrated by ultrasound are the big venous afferent vessels: the iliac, renal and hepatic veins. The left renal vein is positioned ventral to the aorta. 0HVHQWHULFYHLQV The superior mesenteric vein and the splenic vein join in the confluens to form the portal vein. The splenic vein is the main landmark for detecting the pancreas. The other mesenteric veins are not as easily seen in routine examination. 3RUWDKHSDWLVEORRGDQGELOH The ultrasound properties of blood and bile are identical - since they do not

present any acoustic interfaces, their ultrasound appearance is black (assuming no possible interfering artefacts). The plane of section necessary to visualize the liver hilum best may vary considerably from case to case. As a rule, slim (and tall) patients have a more or less longitudinal course to the hilar structures running in the hepatoduodenal ligament, whereas more obese (and small) patients show a rather transverse course; again, adapting to these individual circumstances by variations in the scanning plane will give the best

General view of the porta hepatis and liver: 1 inferior vena cava, 2 liver veins, 3 portal vein, 4 splenic vein, 5 common bile duct, 6 superior mesenteric vein; liver segments

information. In the first group of patients, more longitudinal sections (in the supine position) will be sufficient, whilst right lateral (maybe even intercostal) sections in left oblique position may be needed in the second group. The course of the portal vein is always dorsal to the course of the common bile duct, with the hepatic artery (or one of its main branches) crossing in between. Lymphatic vessels are not visible on ultrasound either in the liver hilum or elsewhere.

Porta hepatis: 1 common bile duct, 2 portal vein, 3 hepatic artery (note its intercrossing right branch between 1 and 2)

3DWKRORJ\VHOHFWHG The tubular structures of vessels containing blood and bile can be influenced by - FKDQJHV in liquid pressure (resulting in a more or less pronounced increase in vessel diameter),

FKDQJHV in the wall structure (e.g.,sclerosis, partial thrombosis, or inflammation, RFFOXVLRQ (complete thrombosis, tumor, concretions), or by FRPSUHVVLRQ (tumor, lymphoma, inflammation).

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3

2

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1 Infrarenal aneurysma, 2 normal aorta (longitudinal scan) (longitudinal scan)

1

1 Thoracoabdominal aneurysma, 2 liver, 3 right ventricle (longitudinal scan)

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1 Lumen of a giant infrarenal aneurysma, 2 thrombotic portions (transverse ! scan)

1 Single arteriosclerotic plaque, infrarenal abdominal aorta (longitudinal scan)

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1

2

1 1

1 Multiple plaques, abdominal aorta (longitudinal scan)

1a

Right heart failure with 1 dilated cava inferior and 2 dilated hepatic veins (right subcostal scan)

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1b

2

Membranous dissection of abdominal aorta with 1a, 1b lumen portions and 2 dissection membrane (transverse scan)

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1 cava inferior with 2 tumor spread (thrombus-like) in renal adenocarcinoma 3 caudate lobe (longitudinal scan)

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2 2

1 thrombosis of superior mesenteric vein (no colour flow), 2 aorta (longitudinal scan)

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1 thrombosis of left iliacal vein (no colour flow), 2 iliacal artery (left lower abdominal scan)

/\PSKQRGHVDQGO\PSKRPD With the advent of more sophisticated ultrasound devices even normal paravascular lymphnodes in the abdomen may be visible in slim patients. Routinely however only enlarged lymphnodes (either benign or

malignant) can be detected, usually adjacent to the great vessels (aorta, celiac axis, inferior vena cava). They are less pronounced in the liver hilum. The spleen - as a specifically big lymphnode - deserves special attention (see 3.7.).

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4 1 multiple lymphnodes, 2 liver, 3 aorta, 4 vertebral body, 5 celiac axis with 6 hepatic and 7 splenic artery (transverse scan)

1, 2 lymhnodes adjacent to 3 head of pancreas, 4 splenic vein, 5 superior mesenteric artery (transverse scan)

1 2

2

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3 1 multiple lymphnodes anterior and posterior to 2 aorta (longitudinal scan)

arrow: retroaortal lymphnode enlargement (metastatic), 1 abdominal aorta, 2 celiac axis, 3 superior mesenteric artery, 4 liver, arrowhead: left kidney vein (longitudinal section)

3DQFUHDV *URVVPDFURVFRSLF DQDWRP\ The pancreas appears as a more or less carrot-shaped organ without a capsule lying transversely across the aorta and the spinal column. Its main portion - the head - is generally to the right of the second lumbar vertebra. The junction of the head and the body is curved around the vertebral column and the abdominal aorta and the tail lies in the left upper abdomen touching the splenic hilum. The uncinate process as a part of the pancreatic head surrounds the superior mesenteric vein. The head of the pancreas itself is surrounded by the duodenal C-loop, and penetrated by the intrapancreatic portion of the common bile duct. The pancreas is covered by intestinal structures (stomach, small and large intestine) and the left lobe of the liver. The latter serves – in deep inspiration as an acoustic window. ([DPLQDWLRQWHFKQLTXHDQG XOWUDVRXQGVHFWLRQDODQDWRP\ With the scanning probe in a transverse position high up in the epigastrium, a deep inspiration will move the liver downwards for some 3-

5 cm, which in turn will deflect interfering gas-containing intestinal structures. The main anatomical landmarks used for visualising the pancreas are the mesenteric vascular structures which adhere to it, the splenic and mesenteric vein and their junction ( the confluens), forming the portal vein. In gross anatomy, there are no fixed demarcations between the three portions of the pancreas (head, body and tail), and the same is true of course on ultrasound scanning. The visualisation of the non-distended main pancreatic duct as it passes along the body of the pancreas serves as a marker of ultrasound machines which have high resolution capabilties. The normal organ shows soft passive movements caused by aortic and venous pulsations. The head and body of the pancreas are detectable in nearly all patients. The tail region (usually less important) is somewhat more difficult for the ultrasonographer due to its small size, angulated course (with a high variability ) and sometimes hidden position behind the gas filled gastric fundus. If necessary, filling the gastric fundus with non-sparkling water can create a good acoustic window for visualisation of the pancreatic tail.

Ventral view of the extrahepatic bile duct: 1 portal vein, 2 common bile duct, 3 pancreatic duct, 4 duodenum

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Dorsal view of the extrahepatic bile duct: 1 portal vein, 2 common bile duct, 3 pancreatic duct, 4 duodenum

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As in all parenchymatous organs, an ultrasound examination of the pancreas gives information relating to changes in its - SRVLWLRQ, VKDSH, and VL]H, - overall UHIOH[LELOLW\ and

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YDVFXODUDUFKLWHFWXUH (with respect to the main pancreatic duct, the common bile duct, the splenic and mesenteric vein and their junction, the confluens), IRFDOOHVLRQV, and adjacent structures (e.g.lymphnodes).

7 5

1

1 2

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Acute pancreatits with 1 spotted head of pancreas and 2 too good visibility of lumen and * of wall layers of duodena C (transverse scan)

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Acute pancreatitis with 1 swollen head of pancreas obstructing, 2 common bile duct (note 3 distended cystic duct) and 4 fluid filled duodenum, 5 hepatic artery, 6 portal vein, 7 liver, 8 right renal artery,inferior vena cava

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1 enlarged head of pancreas (two weeks after inflammatory episode), 2 splenic vein, 3 liver (transverse scan)

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1 pathological fluid collection, 2 right liver lobe, 3 right perirenal fatty tissue (right lateral scan)

2 3 1 1 6

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1 pancreatitis 2 liver, 3 gastric antrum, 4 superior mesenteric artery, 5 splenic vein /confluens, 6 duodenal C (transverse scan)

Acute pancreatitis: diminuished delineability of pancreas, +...+ swollen duodenal wall, 1 duodenal lumen (transverse scan)

4

1 2

2

3 1 1p

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1 acute pancreatitis with 2 pseudocyst and 3 splenic vein, 4 liver, 5 aorta (longitudinal scan)

1 huge pseudocyst with 1p penetration into the 2 spleen (left lateral scan)

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2

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1 pseudocyst (color-artifact, no bleeding), 2 confluens, 3 gastroduodenal artery, 4 reduced panreas parenchyma, 5 inferior cava, 6 duodenal C, 7 liver (2nd scans)

Highly reflexible spots (probably calcifications in chronical pancreatitis) in 1 head and body of pancreas, 2 gastroduodenal and 3 superior mesenteric artery, 4 aorta, 5 cava inferior, 6 liver

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4 2 1 chronical calcifying panreatitis (confirmed by ERCP) with slight compression of 2 portal vein/superior mesenteric vein, 3 gastroduodenal artery, 4 liver (modified longitudinal scan)



1 multiple pseudocysts, 2 aorta, 3 hepatic artery, 4 cava inferior, 5 liver, 6 confluens (transverse scans)





 

 

 

 

1 reduced pancreas parenchyma in chronic inflammation with 2 marked duct dilatation, 3 splenic vein/confluens, 4 superior mesenteric artery, 5 hepatic, 6 gastroduodenal and 7 renal artery, 8 aorta, 9 left renal vein, 10 liver (transverse scan)











 

1 marked dilatation of main pancreatic duct in chronical inflammation with 2 reduced parenchyma, 3 confluens, 4 superior mesenteric artery, 5 aorta, 6 duodenal C, 7 gastric corpus

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+,* slightly dilated main pancreatic duct 1 confluens, 2 posterior antrum wall, 3 gastric lumen (with highly reflexible ingested material), 4 uncinate process (transverse scan)







 





 1 pancreas tumour with 2 splenic vein, 3h head, 3b body of pancreas, 4 superior mesenteric artery, 5 aorta (transverse scan)





1 tumour of pancreas head with 2 tip of fine needle for aspiration cytology; 3 gastroduodenal artery 4 liver (transverse scan)





1 stent in the stenotic main pancreatic duct in chronic pancreatitis (note the reduced parenchyma) 2 superior mesenteric artery 3 confluens (transverse scan)