Normal USG of Aorta and Coeliac Axis

1. USG of Aorta and Coeliac
axis
Dr.Yash Kumar Achantani
OSR

2. Anatomy
The abdominal aorta is the continuation of descending thoracic aorta at T12 , it is
the main blood vessel in the abdominal cavity that transmits oxygenated blood
from the thoracic cavity to the organs within the abdomen and to the lower
limbs.
The normal abdominal aorta has a clearly defined wall and smooth margins and
tapers very slightly below the level of the renal arteries.
The maximum infrarenal aortic diameter averages 2 cm in adults.
The abdominal aorta lies adjacent to the spine throughout its course, slightly to
the left of midline and ends by dividing in Rt and Lt common iliac arteries at L4
level.

3. Anatomy
The normal iliac arteries are smoothly marginated and uniform in caliber. The
maximum diameter of the common iliac artery (outer to outer) is 15 mm in men
and 13 mm in women. The external iliac and common femoral arteries are slightly
smaller, measuring up to 1 2 mm in men and 11 mm in women. In older
individuals, the iliac arteries may be quite tortuous.
Along its course it gives following branches
(unpaired) coeliac artery (T12), superior mesenteric artery (L1), inferior
mesenteric artery (L3) ,median sacral artery.
(paired) middle adrenal arteries, renal arteries (L1-L2), gonadal arteries (between
L2 and L3),inferior phrenic arteries ,lumbar arteries.

5. Key relationships
• Lies posterior to the median arcuate ligament.
• Anterior and slightly to the left of the lumbar vertebral bodies.
• IVC is on its right.
• Crossed anteriorly by the splenic vein and body of pancreas between the
and superior mesenteric artery origins
• Crossed anteriorly by the left renal vein, uncinate process of the pancreas and
part of the duodenum between the superior mesenteric and inferior mesenteric
artery origins

6. The normal aorta. A composite, longitudinal view demonstrates the entire aorta (Ao)
from the diaphragm, on the left, to its termination, on the right. Note that the aorta
tapers slightly below the level of the superior mesenteric artery(arrow), and that the
aorta follows the course of the spine.
B, Transverse view of the aorta (Ao), the inferior vena cava (IVC), and the spine.
The aorta measures only about 1 . 5 cm in this individual.

7. Normal iliac arteries. A, This coronal view shows the bifurcation of the aorta (Ao)
into the right (RCIA) and left (LCIA) common iliac arteries.
B, The common iliac artery (CIA) is seen to divide into the external (EIA) and
internal (IIA) iliac arteries.

8. USG of Abdominal aorta
PREPARATION
The patient should fast at least 6 hours before examination.
The study should be performed first thing in the morning.
No smoking.
SCANNING TECHNIQUE AORTA
A moderate amount of pressure may be needed to push behind the bowel.
The aorta should be imaged in B mode from the diaphragm.
A Grey scale image of the aorta at the largest diameter, noting intraluminal echoes,
should be obtained.
The maximal AP and Transverse Diameter are measured in the Proximal, Mid and
Distal abdominal aorta.
The maximal AP and Transverse diameters should be measured in the origin of the
iliac arteries.

9. Colour Doppler
The Doppler waveform varies depending on whether flow is sample cranial to or
below the renal arteries:
Cranial to renal arteries, there is an appreciable diastolic component, as occurs in
areas with low resistance.
Below this there is no diastolic component, and the trace is characterized by a small
inverted wave (districts with high resistance).

10. (A) Cranial to renal arteries, there is an appreciable diastolic component, as occurs in
areas with low resistance.
(B) Below renal arteries there is no diastolic component, and the trace is
characterized by a small inverted wave (districts with high resistance).

11. Atherosclerosis
Atherosclerosis is characterized by the formation of atheroma, which are raised,
fibroadipose plaques that develop within the intimal layer of the artery or within the
innermost layers of the tunica media.
With time and progression of the disease, the fibrous component prevails, giving
the plaque a pearly appearance. Some atheromas undergo calcification or
ulceration, and mural thrombi can form over complicated and uncomplicated
atheroma. As a result, the vessel wall becomes deformed and rigid, and the luminal
narrowing severely impairs blood flow to the organs.
Focal lesions weaken the arterial wall and predispose them to the aneurysmal
dilatation and rupture.

12. Atheroma of the
abdominal aorta
Atherosclerotic
aneurysm of the
abdominal aorta
Atheromatous plaque of the
abdominal aorta

13. Aortic aneurysm
An artery is considered aneurysmal when its diameter equals or exceeds 1.5
times the normal diameter.
Types of aneurysm
On the basis of shape- Saccular, Fusiform.
On the basis of pathology- True, False and Mycotic aneurysm.
True aneurysm- The composite layers of the vessel wall are intact but stretched
in true aneurysms. The great majority of aortic and iliac aneurysms are true
aneurysms. True Aneurysms represent focal weakening and stretching of the
arterial wall.
False aneurysm- A false aneurysm occurs when a hole in the arterial wall permits
the escape of blood, which is subsequently confined by surrounding tissues.

14. The extravasated blood forms a hematoma into the center of which blood
continues to circulate. The aneurysm is "false" because it is not confined by an
arterial wall.
Most false aneurysms result from iatrogenic arterial puncture followed by
inadequate hemostasis, but false aneurysms may also result from
violent trauma or localized destruction of the arterial wall by an infectious agent.
The term mycotic aneurysm is used for infection-related lesions.
SITE- Aortic aneurysms are usually localized to the infra renal portion of the aorta
aorta and the common iliac arteries.

15. A, Normal arterial wall components are shown.
B, In a true aneurysm, the components of the arterial wall are "stretched.“
C, In a false aneurysm, a hole is present in the arterial wall, with an adjacent
confined collection of blood.

16. Aneurysm Presentation
Symptomatic aneurysms present with abdominal, back, or leg pain.
Substantial leakage, or frank rupture, causes prostration or shock and is
a catastrophic event.
The risk that an abdominal aortic aneurysm may rupture increases with aneurysm
size.
Aneurysm Diagnosis
The primary criterion for the sonographic diagnosis of an arterial aneurysm is a
focal increase in the caliber of the artery, with the diameter of the dilated
segment measuring at least 1 . 5 times greater than adjacent unaffected
segments. For aortic aneurysms, an additional feature is the
absence of tapering of the aorta below the mesenteric and renal vessels.

17. Aortic aneurysms have various gross configurations.
Bulbous- Sharp junction, or neck, between the normal and aneurysmal
portions.
Fusiform- Has a gradual transition between the normal and aneurysmal
portions.
Many aneurysmal aortas are tortuous, and the aorta typically elongates as it
dilates. Tortuous aortas usually deviate to the left of the spine.
Concentric layers of thrombus usually line the interior of large aortic
Aneurysms. Because of the presence of thrombus, the outer dimensions of an
aneurysm are often much greater than the dimensions of the lumen.
Therefore, catheter arteriography usually underestimates the size of an aortic
aneurysm.

18. A, Longitudinal, and
B, transverse, gray-scale sonograms show measurement of Fusiform AAA.

19. Aorta with saccular aneurysm.
A, Viewed in the longitudinal plane, the aorta appears normal.
B, Transverse imaging of the aorta is required to reliably detect this type of
aneurysm. With a saccular aneurysm, unless a longitudinal image can be
obtained in the plane of the greatest diameter of the aorta, transverse imaging must
be used to measure the greatest diameter.

20. Measurement difficulties caused by aortic tortuosity.
A , Note that the diameter of this tortuous aorta is exaggerated with a true transverse
view and is correctly measured only in an oblique view. Coronal images eliminate
this problem.
B, Composite coronal view of a markedly tortuous, aneurysmal aorta.

21. Thrombus within an aneurysm.
Concentric layers of thrombus surround the
arterial lumen (L).

22. Colour Doppler
On Color Doppler, the aneurysm is characterized by swirling flow with decreased
linear velocity
The figures show the Colour
Doppler flow of an abdominal
aortic aneurysm

23. Examination Protocol for Aortic Aneurysms
1. Longitudinal
• Examine aorta, diaphragm to bifurcation.
• Use color flow to identify dissection, if present.
• Determine location and longitudinal extent of aortic aneurysm.
• Measure aortic aneurysm anteroposterior diameter, outer to outer.
2. Transverse
• Document the maximum diameter of the aorta at the diaphragm, superior
mesenteric artery, and distally near the aortic bifurcation.
• Measure aneurysm anteroposterior and transverse diameters, outer to outer.

24. 3. Coronal
Measure aortic aneurysm, transverse dimension, outer to outer.
4. Color Doppler examination
• If examination time permits, confirm patency of superior mesenteric, celiac,
renal arteries, and examine for flow disturbances associated with stenosis.
• Measure distance from renal arteries to aneurysm neck.
• Alternatively, measure distance from superior mesenteric artery to aneurysm
neck.
5. Kidneys: longitudinal and transverse views
• Document kidney length and normal features.
• Document hydronephrosis, if present.

25.  Remember, aneurysms do not decrease in size! To avoid mistake, be aware
of the measurements reported previously before giving current
measurements.
 The renal arteries arise no more than 2 cm below the superior mesenteric
artery; therefore, the renal arteries should be unaffected if the aneurysm
begins 2 cm or more below the superior mesenteric artery.

26. Aneurysm measurement technique.
A, Longitudinal view of a distal aortic
aneurysm measuring 4 cm in maximum
anteroposterior dimension. The spine is visible
posteriorly.
B, As seen in the coronal scan plane, the
transverse dimension is 4.7 cm. Note that both
the aorta (Ao) and inferior vena cava (IVC) are
visible in the coronal plane.
C, transverse view demonstrates the anterior
and posterior surfaces of the aneurysm clearly
(4.2 cm). The lateral surfaces are less clearly
seen.

27. D, The distance from the superior
mesenteric artery to the neck of the
aneurysm is 4.4 cm.
E, Long-axis view of the right common iliac
artery with focal dilatation of 18-mm
diameter.
F, Long-axis view of the left common iliac
artery with focal dilation of 16-mm
diameter.

28. Inflammatory Abdominal
Aortic Aneurysm
Inflammatory AAAs constitute approximately 5% of all AAAs.
Inflammatory AAAs are recognized by extremely thickened aortic wall and
surrounding fibrosis that tends to spare the posterior wall.
Inflammatory AAAs are less prone to rupture than other AAAs but are more prone
to producing symptoms such as back pain.
Anti-inflammatory drugs may be used to treat the inflammation. With surgical or
endovascular treatment, the inflammation surrounding many AAAs resolves.
Sonographically, inflammatory AAAs may be recognized by a rind of tissue
surrounding the aorta

29. Inflammatory AAA with a rind of tissue approximately 7 mm in thickness projecting
outside the anterior and lateral walls of the abdominal aorta (arrows). A, Longitudinal,
and B, transverse, sonograms.

30. Aneurysm Complications
Potential complications of aortic aneurysms are atherosclerotic renal and
mesenteric artery obstruction, hydronephrosis (from aneurysm compression of
a ureter), retroperitoneal fibrosis, and aneurysm rupture.
The most disastrous complication of aortic aneurysm is rupture.
The demonstration of a retroperitoneal hematoma provides direct
evidence of aortic rupture. The hematoma is hypoechoic
and is usually unilateral or asymmetric. It typically displaces the ipsilateral kidney.
Peritoneal fluid may also be present if the aneurysm has leaked into the peritoneal
space.

31. Treatment
The traditional method of aortic aneurysm repair is surgical bypass grafting, using
synthetic graft material.
A second repair method has come into widespread clinical use; namely,
endoluminal aortic stent grafting. This procedure is less invasive and traumatic
than abdominal surgery and requires only a brief hospital
stay; therefore, it has been widely adopted as a primary aneurysm repair method.
Three types of surgical graft procedures have commonly been used for aortic
aneurysm repair:
(1) Simple tube grafts for aneurysms limited to the aorta.
(2) Aortoiliac grafts
(3) Aortobifemoral grafts.

32. The distal anastomosis is end-to-end for aortoiliac grafts and end-to side
for aortofemoral grafts. The end-to-side configuration permits retrograde external
iliac artery flow needed to supply blood to the internal iliac branches.
The graft material used for aortic bypass generally has a textured, or tram track,
appearance, and is fairly echogenic; therefore, the graft can usually be identified
easily. The exception to this rule is an old graft (e.g., >8 yr) that is invested with
fibrous tissue or atherosclerotic plaque.
A small layer of fluid is normally present around the graft during the
postoperative period and this fluid should decrease in volume with time and
ultimately disappear. Increasing fluid volume suggests graft infection.

33. Types of aortic grafts.
A, Tube graft with end-to-end
proximal and distal anastomoses.
B, Aortobifemoral graft with end-to-
end distal anastomoses.
C, Aortobifemoral graft with end-to-
side distal anastomoses.
D, The native aorta is wrapped
around the graft and sewn closed.

34. Sonography of an uncomplicated
aortobifemoral graft.
A, Proximal end· to-end anastomosis
of the mildly dilated aorta (Ao) and the
smaller-diameter graft (G).
B, End-to-side anastomosis of the left graft
limb (G) with the common femoral artery
(CFA).
C, Color flow image, same as part B.

35. Complications
Complications of aortic graft surgery may be divided into early and late periods.
Early complications (weeks/months)- Hematoma, Seroma and Abscess.
When abscess is diagnosed, it is important to determine whether the collection
is immediately adjacent to the graft or remote from
it. A remote abscess (e.g., in a surgical incision) may be drained percutaneously
without significant clinical consequences, while a perigraft abscess necessitates
graft removal.

36. A large postoperative fluid collection
(F) is present between the aneurysm sac
and the body of this graft (G).
An abscess (A) is present in a groin
incision. Unfortunately, the abscess
extends to the graft (G), implying that the
graft is infected as well.

37. Late complications
True aneurysm at the anastomoses site.
Pseudoaneurysm at the anastomoses site.
Stenosis and occlusion (usually at the distal site in the runoff vessel)

38. Graft pseudoaneurysm. A large
pseudoaneurysm (PA) extends both
superficial and deep to the distal
anastomosis of an aortoexternal
iliac bypass graft.
Mass like epigastric aneurysm at aortic
graft anastomosis.
Sonography demonstrating a hypoechoic
mass (M) located slightly to the right of the
aorta, in the vicinity of the pancreatic
Head arising from graft aorta anastomosis.

39. Complications with Endoluminal
grafts
Thrombosis
Infection
Stenosis (graft kink, neointimal hyperplasia, atherosclerosis)
Anastomotic pseudoaneurysm.
Endoleak
An endoleak is an area of the AAA that has been excluded by the
endoluminal graft (ELG) that nonetheless continues to have blood flow.
There are four types of endoleaks.
Type 1 leak (attachment leak).
Type 2 leak (branch artery leak).
Type 3 leak (loss of integrity of ELG)
Type 4 leak (fabric porosity)

40. Type 1 leak (attachment leak).
Blood continues to enter the aneurysm sac at one of
the three ends of the bifurcated ELG. T/t is indicated
in this leak
Type 2 leak (branch artery leak). Blood enters the
aneurysm sac through a patent branch artery. Self
limiting but t/t needed if there is increase in size.
Type 3 leak (loss of integrity of ELG).
Either the modules of the ELG have become
separated or a rent has formed in the fabric of the
ELG. T/t must.
Type 4 leak (fabric porosity). Blood enters the sac
from the ELG lumen through intact cloth of the ELG.
This is self-limited and present only at surgery.

41. STENOTIC DISEASE OF
THE ABDOMINAL AORTA
Stenosis or occlusion of the abdominal aorta can be congenital or may be caused
by atherosclerosis, vasculitis (arteritis), trauma, or embolus. Dissection may also
result in stenosis.
Midaortic syndrome is a rare congenital stenosis that is also called abdominal
coarctation.
Symptoms of aortic stenosis or occlusion may include intermittent claudication
and impotence. These symptoms, along with the finding of decreased femoral
pulses, are called Leriche syndrome.
In most cases of suspected aortic stenosis, it is prefered to evaluate the aorta with
CTA instead of duplex because maintaining a proper Doppler angle of 60 degrees
or less can be difficult .However, situations still arise in which aortic or iliac duplex
Doppler sonography is indicated to assess for
stenotic disease.

42. Stenotic aortic bifurcation.
A, Duplex Doppler sonogram shows velocity of greater than 500 cm/sec at stenosis at
at the aortic bifurcation. Proximal to the stenosis, the aortic velocity varied from 35 to
50 cm/sec.
B, CTA shows very focal stenosis of the abdominal aorta at its bifurcation.

43. Aortic dissection
This condition occurs when blood enters the media of the vessel through a rent
in the intima and then dissects along the length of the artery.
The intima, and in some cases part of the media, are stripped away, and a new
lumen, called the false lumen, is formed. Blood may flow freely through both
the false lumen and the original (true) lumen to
supply branch vessels.
Aortic dissection begins almost invariably in the chest and extends into the
abdomen.
The most common site at which aortic dissection begins, however, is
just below the left subclavian artery. The second most common site is the
ascending aorta.

44. In arterial dissection, a hematoma forms
between components of the wall.

45. The distinguishing ultrasound finding in arterial dissection is a membrane that
divides the arterial lumen into two compartments. This membrane consists of the
intima and, in some cases, a portion of the media. The membrane moves freely
with arterial pulsations if it is thin and if both the true and false lumens are
patent.
Duplex examination may demonstrate flow in both lumens, but different
flow rates may be present, and in some cases, flow in the false lumen may be too
slow to be detected.
The diameter of the aorta is generally increased by dissection but not as
dramatically as with a true aneurysm.

46. Aortoiliac dissection.
A, longitudinal view of the abdominal aorta
shows a dissection membrane (arrows).
B, Blood flow is present in both lumens.
C, Transverse view of the aorta shows the
apparent true lumen(arrow) and the
adjacent false lumen. IVC, inferior vena
cava.

47. Coeliac axis
The celiac artery, also called the celiac trunk or celiac axis, is the most cephalad
visceral branch of the abdominal aorta. It arises from the anterior aortic surface.
It then bifurcates about 1 to 3 cm from its origin into the common hepatic and
splenic arteries, which are readily visualized with ultrasound.
The celiac artery also gives rise to the left gastric artery, which is generally not
visible sonographically.
Ultrasound visualization of the celiac artery is best in the transverse plane, in
which the T-shaped bifurcation of the vessel is characteristic.
The celiac artery origin is also seen readily in longitudinal images, but the
branches are not well seen in this plane.

48. The celiac artery and its branches.
Transverse sonogram of the celiac axis (C)
as it divides into the common hepatic
artery (CHA) and splenic artery (SA).
Ao, aorta; lVC, inferior vena cava; SV, a
segment of the splenic vein.

49. Variants of coeliac trunk

50. Colour Doppler
Celiac artery Doppler signals have a characteristic low-resistance flow pattern,
with a large amount of continuous forward flow throughout diastole, but a slightly
higher resistance pattern is seen near the origin of the vessel.
Normal, low-pulsatility Doppler signal in the distal portion of the
celiac artery. Peak systolic velocity is 133 cm/sec, and end diastolic
velocity is 47 cm/sec.

51. If the celiac artery is occluded, collateralization occurs through the
pancreaticoduodenal arterial arcade, which is a network of small vessels
surrounding the pancreas and duodenum.
With the celiac trunk occluded, these vessels enlarge and feed into the
gastroduodenal artery, which reverses flow in order to supply blood to the
common hepatic artery.
Because of abundant opportunities for collateralization, hepatic or
splenic artery blood flow may appear normal, even though the origin of the celiac
artery is occluded.

52. Splenic Artery
The splenic artery follows a tortuous course along the posterosuperior margin of
the pancreatic body and tail and terminates by splitting into a number of branches
in the hilum of the spleen.
Along the way, the splenic artery gives rise to several pancreatic branches, short
gastric branches, and the left gastroepiploic artery.
Because of the tortuous course of the splenic artery, flow in this vessel is typically
turbulent.

53. Splenic artery anatomy.
Normal, low pulsatility Doppler signal from the splenic
artery. Peak systolic velocity is 110 cm/sec, and end-
diastolic velocity is 45cm/sec

54. Hepatic Artery
The common hepatic artery is the limb of the celiac trunk that heads towards the
patient's right.
After running a short distance common hepatic artery gives rise to the
gastroduodenal artery, which can often be seen with ultrasound at the antero-
superior border of the pancreatic head.
Beyond the gastroduodenal artery origin, the common hepatic artery becomes the
proper hepatic artery, which follows the portal vein to the porta hepatis (entrance
to the liver) .
At this point, it divides into the left and right hepatic arteries, which penetrate into
the hepatic substance.

55. The hepatic artery and its branches.

56. Anatomic relationships among the hepatic
artery, the portal vein, and the extrahepatic
bile ducts.

57. Variations of hepatic artery
Hepatic artery variation Michel’s
classification
Hyatt’s classification
Normal anatomy Type I Type I
Replaced left hepatic artery (LHA) originating from the left
gastric artery (LGA)
Type II Type II
Replaced right hepatic artery (RHA) originating from the
superior mesenteric artery (SMA)
Type III Type III
Co-existence of Type II and III Type IV Type IV
Accessory left hepatic artery originating from the left
artery
Type V Type II
Accessory right hepatic artery originating from the superior
mesenteric artery
Type VI Type III
Accessory left hepatic artery originating from the left
artery and accessory right hepatic artery originating from
superior mesenteric artery
Type VII Type IV
Accessory left hepatic artery originating from the left
artery and replaced right hepatic artery originating from
superior mesenteric artery
Type VIII Type IV
Common hepatic artery originating from the superior
mesenteric artery
Type IX Type V
Right and left hepatic arteries originating from the left
artery
Type X NOD
Common hepatic artery directly originating from the aorta NOD Type VI

58. The hepatic arteries are usually well visualized sonographically from an anterior
abdominal approach. The common hepatic artery is most easily identified at its
origin from the celiac artery.
The proper hepatic artery is seen on ultrasound images near the porta hepatis that
show the portal vein in short or long axis.
The right and left hepatic artery branches can be followed into the substance of the
liver to a variable distance from the porta hepatis.
The hepatic arterial system has low-resistance flow characteristics, with a
large amount of continuous forward flow throughout diastole.

59. Ultrasonography of the hepatic artery.At
the porta hepatis, the hepatic artery (HA)
can be differentiated from the bile duct
(BD), because blood flow is present in the
former and not in the latter.
Doppler examination confirms the identity
of the (proper) hepatic artery, which has
low-resistance arterial signals.