ACQUIRED AORTIC ABNORMALITIES Hidayatullah Hamidi Fourth Year Radiology Resident FMIC, Kabul, May 2016 WWW.AFRAD.ORG

کسی که خوب فکر می کند لازم نیست زیاد فکر کند

Pre Presentation Self Assessment What is Acute aortic syndrome? Which site of aorta is more prone to laceration in traumatic injury What is the aim of performing CT in a sonographically detected AAA How to DDx true Vs False lumen in aortic dissection? What is Mid aortic syndrome

Traumatic aortic injury (TAI) 1 Traumatic aortic injury (TAI) Site Blunt or penetrating injury 80–90%: Complete rupture →immediate death. Half of 10-20 %: Adventitia is intact (False aneurysm) Severity: Intimal haemorrhage/Laceration, Medial laceration Complete laceration, False aneurysm, Peri-aortic haemorrhage. Image: http://eradiology.bidmc.harvard.edu/LearningLab/cardio/Briggs.pdf

Imaging: Radiographic findings Based on presence of mediastinal hematoma Widening of mediastinum: 92.7% Mediastinal width (at level of aortic arch): >8 cm M/C ratio (at level of aortic arch): >¼ M/C ratio: >1/4 Widening of right paratracheal stripe

Imaging: Thoracic aortography Intimal flap Dissection: linear filling defect Pseudoaneurysm: Discontinuity/irregularity of aortic contour Luminal filling defect: Thrombus formation Pseudoaneurysm at aortic concavity just distal to arch Linear lucency traversing the aortic lumen

Imaging: CT Angiography Depicts direct and indirect signs Intimal flap Pseudoaneurysm Mediastinal haemorrhage

Acute Aortic Syndrome (AAS) Three closely related emergency entities Aortic Dissection (AD) Intramural Hematoma (IMH) Penetrating Atherosclerotic Ulcer (PAU) Clinically indistinguishable but CT initial diagnosis Differentiation Disease staging

2 Aortic dissection Non-traumatic acute aortic emergency Unknown etiology but related to advancing age and hypertension. Classic dissection: Intimal tear →Blood splitting the medial layer. False lumen separated from true by an intimomedial flap. Less elasticity of false lumen wall → aneurysmal dilatation.

Classification To decide for surgical Vs medical treatment

Imaging purpose: Establish diagnosis, define extent, identify true and false lumens, assess for presence of complications Type A Intimal flap in arch Type B: Entry point distal to left SCA

Abdominal Aortic dissection Collapse of true lumen. The coeliac axis, SMA and RRA arise from the true lumen. LRA arises from the false lumen Acute type B dissection in patient with mesenteric ischemia

True Vs False lumen True False Surrounded by calcifications (if present) Smaller than false lumen Usually origin of celiac trunk, SMA and RRA Flow or occluded by thrombus (chronic). Delayed enhancement Wedges around true lumen (beak-sign) Larger than true lumen Circular configuration Outer curve of the arch Usually origin of LRA

3 Intramural Hematoma What the clinician needs to know Type A or B Predictors of mortality:  - Ascending Aorta > 5 cm - IMH thickness > 2 cm - Pericardial effusion IMH may persist or evolve into aneurysm or PAU Associated PAU - worse prognostic outcome

Penetrating Atherosclerotic Ulcer 4 Penetrating Atherosclerotic Ulcer Ulceration of an atheromatous plaque that has eroded the inner elastic layer of the aortic wall. It has reached the media and produced a hematoma within the media. What the clinician needs to know Type A or Type B Single or multiple Associated IMH

Imaging features Extensive atherosclerosis + intima calcifications/atherosclerotic plaques Focally displaced and separated intima calcifications Contrast extravasation Focal IMH,

AD & PAU Contrast tracking into aortic wall outside the confines of the normal lumen. Penetrating atherosclerotic ulcer. Aortic wall thickening due to intramural haematoma.

Inflammatory diseases and mid aortic syndrome 5 Inflammatory diseases and mid aortic syndrome Granulomatous vasculitis (Takayasu's disease): Chronic inflammatory disease of aorta, branch & PAs. Mid aortic syndrome: Segmental narrowing of proximal abdominal aorta and ostial stenosis of major branches Narrowing of Celiac trunk and abdominal aorta 20Y, F: Thickening of all layers of descending aortic. Elevated ESR, Dx: Takayasu's disease

6 Aortic aneurysms Characterized by degeneration and remodelling of aortic wall. Commonly atherosclerotic, but also result from trauma, infection, syndromes Commonly affects the aortic root, ascending aorta and arch.

Atherosclerotic aortic aneurysms 7 Atherosclerotic aortic aneurysms 95% affect the abdominal rather than the thoracic aorta. Natural history: Progressive remodelling, expansion and eventual rupture.

Aim of CT evaluation AP and transverse size of AAA. Diameter of aorta at levels of and just below visceral arteries Length of aneurysm neck from lowest RA Shape of neck; conical Angulation of the neck in AP and lateral planes Presence of excessive atheroma in the neck Any accessory RAs Distance from lowest RA to aortic bifurcation. Tortuosity and degree of calcification of iliac arteries. Diameter of the common iliac arties

References

Post Presentation Evaluation Dx Type True Vs False Clues

Collageneous media-remnants (cobwebs sign)

Dx Type True Vs False Clues

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