3. Introduction
Continuation of thoracic
aorta at diaphragmatic
hiatus(12th thoracic
vertebra)
It is 12cm long,2-3cm wide
It lies anterior to T12/l1 to l4
vertebrae
Accompanied by the
thoracic duct, azygous and
hemi-azygous vein, the
sympathetic trunk and
splanchnic nerve.
3
4. Relations
the diaphragmatic crura
enveloped the anteriolateral
surface of the abdominal
aorta at the hiatus.
Posteriorly
it lies along the anterior
aspect of the lumbar
vertebrae slightly to the left
and closed to the left psoas
muscle
The left lumbar veins passes
posterior to abdominal aorta
4
5. Relations
• IVC lies right to it
Anteriorly
• splenic vein and
body of pancreas,
left renal vein,3rd
part of the
duodenum.
Posterior
• left psoas, left
lumbar vein
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6. Branches of the abdominal aorta seen on
angiogram
as follows:
• Three unpaired anterior branches:
Coeliac trunk at T12/L1
Superior mesenteric artery at L1
Inferior mesenteric artery at L3
• Three lateral paired visceral arteries:
Adrenal arteries at L1
Renal arteries at L1/L2
Gonadal arteries at L3
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7. Cont’d
• Five lateral paired parietal branches:
Inferior phrenic arteries at T12
Four pairs of lumbar arteries
• Terminal arteries:
The common iliac arteries
Median sacral artery.
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9. Radiological anatomy of abdominal aorta
and its major branches
The following imaging modalities are used for demonstrating
the abdominal aorta and it major branches:
Ultrasonography
Angiography
Computed tomography(CT) and CT angiography
Magnetic resonance imaging(MRI)
MRI angiography
Radionuclide imaging(RN)/ RN angiography
Plain radiograph
Others not routinely used includes:
Intravascular ultrasonography
ANGIOSCOPY
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10. Ultrasonography
It is a non-invasive imaging modality
Cheap and readily available
Does not use ionizing radiation
Abdominal aorta is visualized posterior to
the pancreas, where coeliac and superior
mesenteric arteries are easily seen
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11. Pulsatile hypo echoic tubular structure with
brightly echogenic wall anterior to the
spine on longitudinal scan.
On transverse scan it is seen as a
rounded hypo echoic structure with
echogenic wall.
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15. Doppler ultrasound of the Aorta
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• Sharp increase
antegrade flow velocity
followed
• Rapid decrease that
bottoms out in early
diastole with a brief
period of reversed flow.
• Low velocity
antegrade flow then
resumes and continue
for the rremainder of
diastole.
22. Intravenous Ultrasonography
• Uses IVUS catheters with silicon PEC of
20-40mhz.
• Reflected sound wavs visualizes the
arterial wall in 2D, tomographic format,
• analogous to the histologic cross section
• Can be Diagnostic or Interventional
procedures
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24. Angiography
Contrast investigation of the aorta and it
branches
It is an invasive procedure
It uses ionizing radiation
The aorta and its branches are seen as
tubular branching structures with reduction in
caliber from above downward.
All major branches of the aorta are
demonstrable on angiograpic films
The branches are:
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25. Computed tomography and CT angiography
Both axial and coronal images can demonstrate the
abdominal aorta either on plain or post contrast study
With CT angiography tiny branches of the abdominal aorta
can be demonstrated
Axial CT demonstrate the axial relations of the abdominal
aorta, it branches to other abdominal structures
On pre-contrast slices it is seen as a well circumscribed
hypodense structure anterior to the lumber vertebrae and to
the left of midline .
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26. The aorta is seen posterior to the pancreas
The major branches of the aorta are seen supplying the
accompany structures
e.g. renal arteries are traced to the kidneys, spleenic
artery is traced to the spleen
CT angiography, digital subtraction angiography can
demonstrate the abdominal aorta and it major branches.
They are seen as hyperdense tubular branching
structures.
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27. CT at supra renal level demonstrating abd.
Aorta and it branches
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34. Magnetic resonance imaging and MRI
angiography
It is non invasive method of demonstrating
abd. Aorta and its branches
Has the advantage of demonstrating the
vessel without the use of contrast
Non ionizing technique
It is expensive and not readily available in
this environment
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35. On T1WI and T2WI flowing blood
produces a signal void thus, appear black
But by using time-of-flight and phase
contrast fast gradient echo sequence they
produce high signal thus appears white.
And the aorta and it major branches are
demonstrated
Anterior branches are demonstrated on on
sagittal views while, the lateral branches
best seen on a plane parallel to their
course.
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37. Radionuclide imaging
Though no longer perform but can be use
to demonstrate abdominal aorta and it
major branches.
It is expensive and uses ionizing radiation
Done by injection of radiopharmaceuticals
into the artery and activity measured by
gamma camera.
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38. Plain films
Uses ionizing radiation
though cheap and
readily available
The abd. Aorta and its
major branches are not
demonstrable on plain
radiograph except if
calcified
if calcified, It is then
seen as linear
calcification vertically in
the midline and to the
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39. Tortuosity of the aorta in the elderly may
cause considerable variation in the site of
this calcification.
Proximity of the vertebral bodies may lead
to bony erosion by aneurysms of the aorta,
which may be detectable on radiographs.
Bony erosions of the anterior vertebral
bodies are seen in aneurysms of the
abdominal aorta causing Scalloping
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40. others
• Not routinely used includes:
Angioscopy
Elastography
Optical Coherence Tomography
Intravascular Nuclear Imaging
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41. References
• Weirs imaging anatomy Atlas
• Anatomy of Diagnostic Imaging by Ryan.
• Online sources; Slideshare, Radiopedia.
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Retroaortic left renal ein in 2percent population,circumaortic left renal vein, nutcracker syndrome
superior mesenteric artery sndrome
The aorta is distinguished from the IVC by the aorta remaining posteriorly placed to reach the aortic hiatus while, the IVC passes anteriorly to pierce the central tendon of the diaphragm.
Superior mesnteric artery syndrome=3rd part of the duodenum compression
Nutcracker synrome=of the left renal artery compression
Clearly defined wall and margins, tapers slightly downwards averages 2cm dependent on age ,race gender and body size,
lies adjacent to the spine in its course
Flow pattern plug flow, High resistance wit sharp increase antegrade flow velocity followed by a rapid decrease that bottoms out in early diastole with a brief perio of reversed flow. Low velocity antegrade flow then resumes and continue for the rremainder of diastole.
low resistance
coulour and pulsed doppler is performed for the splanchnic arteries to evaluate for insufficiency of intestinal blood flow in patients presenting with abdominal pains atypical.
it icludes the evaluation of the abdominal aorta, celiaic, SMA,IMA
Celiac artery doppler signals have a characteristic low resistance flow pattern with large amount of continous forward flow throughout diastole ,with high end diastolic velocities but a slightly higher resistance pattern is seen near the origin of the vessel.
because of the tortous course of the splenic artery flow vessel is typically turbulent
Diagnostic applications- ambiguous angiograms,and intermediate coronary lesions,---evaluation of the left main coronary artery---evaluation of transplant vasculopathy
Interventional applications=Vessel sizing, IVU imaging in coronary stenting, strut malapposition, Stent repositioning,
lumen area-area confined in lumen-intima interface
total vessel area-area confined within the external elastic lamina
wall area= total vessel area-lumen area
wall area=plague area or plague plus media area...percentage plague area =plague burden =percentage cross setional narrowing