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Doenças Cardiovasculares > TP2.4 - Imagiologia da Aorta Torácica > Flashcards

TP2.4 - Imagiologia da Aorta Torácica Flashcards

1
Q

Assessement of the thoracic aorta?

A
  • Plain radiography
  • TTE
  • TEE
  • MDCT (multidetector ct)
  • MRI
  • Digital Subtraction Angiography
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2
Q

Multidetector CT (MDCT)?

A

Isotropic resolution
Rapid scan times
Wider availability
With ECG gating, avoiding motion artifacts in the ascending aorta
Since ECG gating is associated with increased radiation dose, various dose reduction techniques are used

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3
Q

CE-MDCT?

A

GFR > 45 ml/min iodinated contrast can be administred without any preparation
GFR between 30 and 44 ml/mi, previous hydration and N-acetylcysteine
GFR < 30ml/min contrast should not be administered

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4
Q

Principles of CT Angiography?

A 
Multidetector CT technology
Dual source CT
Protocol examples:
- Helical non-gated CTA
- ECG-synchronized CTA
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5
Q

CT Angiography - achieve arterial enhancement?

A

Need intravenous contrast to achieve arterial enhancement
Proportional to the iodine administration rate:
- increase iodine concentration
- increasing injection flow rate ( 5ml/s , enhancement increases and duration decreases, too high appear artifacts from pooling)
- longer injection duration

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6
Q

Saline chaser?

A

Pushes contrast in tubing and peripheral veins into central veins
Allows reduction in contrast volume
Increases peak attenuation
Reduces artifacts from veins and right heart
Simpler to implement with dual injectors

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7
Q

Attenuation?

A

Attenuation increases with lower kVp

Noise increases with lower kVp

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8
Q

Time to peak?

A

TIme to peak enhancement differs for different target arteries
Differ due to local vascular pathology

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9
Q

Timing bolus?

A

Select target location from scout topogram
Inject small test-bolus 15-20ml contrast
Acquire low-dose dynamic scan at specified location during injection
ROI in target structure

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10
Q

Bolus triggering?

A

Select trigger location
Acquire reference image
Inject contrast bolus
Place ROI in vascular structure of interest
Start scan when desired threshold reached

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11
Q

Magnetic Ressonance Angiography?

A

Advantage

  • relying on the intrinsic magnetic properties of body tissues and blood
  • external magnetic field to produce imaging
  • without the need of ionizing radiation or nephrotoxic contrast agents
  • high-quality images
  • excellent spatial resolution
  • shorter times
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12
Q

NCE-MRA?

A

Time of flight:
- Most commonly used
- Especially for peripheral and intracranial applications
- Venous signal could potentially obscure the visualization of adjacent arteries, so it is suppressed by a saturation band
Steady-State Free Precession MRA:
- T2/T1 ratios
- Both arteries and veins have bright signals
- Thoracic applications
- Venous inflow suppression can be applied
Phase Contrast MRA:
- Singal proportional to the velocity of moving blood
- longer image acquisition times
- calculate pressure gradients, wall shear stress,…

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13
Q

CE-MRA?

A

Used more often than NCE-MRA
Advantages:
- short acquisition times
- improved anatomical coverage
- decreased susceptibility to artifacts caused by blood flow and pulsatility
Parallel imaging (faster. fewer motion artifacts, low energy burden for patient)

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14
Q

Digital Subtraction Angiography?

A
  • Requires subtraction of an X-ray image acquired prior to contrast injection, known as a mask image, from a post-injection image
  • Flat-panel detector technology
  • Single or double arch
  • Virtual angioscopy
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15
Q

Aortic Dilation?

A

Ascending aorta:
- enlarged >4cm, aneurismatic >5cm
Descending aorta:
- enlarged >3cm, aneurismatic >4cm

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16
Q

Thoracic aortic aneurysm?

A
    • Permanent localized dilation either 50% or 2 std larger than normal expected diameter dor the aortic segment
    • Atherosclerosis overall most common cause (70%)
    • Medial degeneration most common cause of ascending aorta aneurysm
    • Atherosclerotic aneurysms most common occur in the descending thoracic aorta
17
Q

Thoracic aortic aneurysm - presentation?

A
    • 6th-7th decades of life
    • male predominance
    • involvement of abdominal aorta in one-third of patients
    • 60% with systemic hypertension
    • Asymptomatic or present with chest pain
18
Q

Complications of Thoracic Aortic Aneurysm? When to intervene?

A

– Larger aneurysms can compress the adjacent structures such as SVC, recurrent laryngeal nerve, esophagus, or coronary arteries
– Dissection and rupture are other complications
– Risk of rupture increases with aneurysm size
– Aneurysms are repaired when:
. ascending aorta exceeds 5.5cm
. descending aorta exceeds 6cm
. aneurysm enlarges more than 1cm per year

19
Q

Annuuloaortic ectasia?

A
    • Symmetric dilation of the aortic root and ascending aorta with effacement of the sinotubular junction
    • Ascending aorta has a pear shape appearance and the arch is of normal caliber
    • Most commonly occurs with Marfan Syndrome
20
Q

Acute Traumatic Aortic Injury?

A
  • 40% mortality rate first 24h without treatment
  • no direct correlation between external findings and degree of aortic injury
  • 95% at isthmus level
  • MCDT if normal, excludes TAI
21
Q

Aortic Trauma?

A

Rapid deceleration injury (aorta fixed at ligamentum arteriosum)
Imaging
– Free rupture, rapidly fatal
– Controlled rupture up to 90% survival

22
Q

Complete aortic rupture?

A
    • Rupture throughout the three layers
    • Isthmus, most frequent location
    • Impending exsanguination, unless hemorrhage is being contained by mediastinal structures giving a pseudoaneurysm appearance
    • Indirect imaging findings: hemomediastinum, left hemothorax, and hemopericardium
23
Q

Traumatic Aortic Dissection?

A
    • Blood extravasation through the intima that dissects progressively between the intimal and medial layers
    • True and false lumen formation
    • True lumen limited by intimal layer and false lumen by medial layer
    • Intimal flap recognition: key for imagiological diagnosis
    • 11% of acute aortic traumatic injuries
24
Q

Non-communicating aortic dissection (Acute Intramural Hematoma)?

A
    • Hemorrhage to the medial layer without intimal rupture
    • vasa vasorum traumatic rupture
    • MCDT: mural thickening, better evaluated in non contrast scans

–some studies suggest that IMH is an early stage or variant of dissection

25
Q

Dissection? Classification?

A
    • Most common cause of acute aortic syndrome
    • Usually the result of systemic hypertension
    • Many other causes

Stanford:
Typer A - 75%, involve the ascending aorta
Type B - 25%, do not involve the ascending aorta
DeBakey:
Type I - tear originates in ascending aorta and propagates to at least arch and often behind it
Type II - tear originates in and is confined to ascending aorta
Type III - tear originates in the proximal descending aorta and extends distally to descending thoracic or thoracoabdominal aorta

26
Q

Aortic Dissection - Complications?

A 
Aortic rupture
Hemothorax
Hemopericardium without or with cardiac tamponade
Acute aortic regurgitation
Aortic branch vessel obstruction
End-organ ischemia
27
Q

Aortic dissection approach according to Type?

A

Type A
- require prompt surgical repair
Type B
- Usually treated medically and require serial follow up with CT or MRI
- Type B dissections with complications require endovascular or surgical repair

28
Q

Penetrating Atherosclerotic Ulcer?

A
    • Ulceration of the aortic wall
    • Usually by atherosclerosis
    • Most common in the mid descending aorta or arch
    • Begins as an atherosclerotic intimal ulcer (stage I), evolving into an intimal tear (stage II), followed by hemorrhage into the media (stage III) and finally resulting in a full-thickness penetration of the aortic wall (stage IV)
    • CE-MDCT
29
Q

Mycotic aneurysm?

A 
Infectious aneurysm caused by nonsyphilitic organisms:
- Staphylococcus
- S. pneumonia
- Gonococcus
- Salmonella
Aortic intima resistant to infection
Predisposing factors:
- weakening from atherosclerosis
- bacterial endocarditis
- drug abuse
- trauma
More common in the ascending aorta
Can be multiple, usually saccular with a wide neck
30
Q

Aortitis?

A
    • Aortitis (vasculitis) is characterized by the presence of leucocytes in the aorta wall, with reactive damage to mural structures
    • Takayasu arteritis and giant cell arteritis are the most common
31
Q

Takayasu Arteritis?

A
    • Idiopathic arteritis
    • Women ++
    • Asians
    • It destroys the arterial media, resulting in aneurysms and rupture
    • Early systemic phase with non-specific constitutional symptoms
    • Late phase with signs and symptoms of vascular disease
32
Q

Classification of Takayasu Arteritis?

A 
Type 1 - classic pulseless
Type 2 - mixed
Type 3 - atypical coarctation
Type 4 - dilated
It typically affects the aorta and its primary branches and can involve a focal region of the aorta or the entire vessel. Can be aneurysmal or occlusive
33
Q

Imaging of Takayasu Arteritis?

A
    • CT and MRI can show thickening of the vessel wall and mural contrast enhancement in early stages
    • Stenosis, occlusion and aneurysms
    • Thickened aortic cuspids and pericardial effusion or thickening may also be present
    • Treatment: HIgh dose steroids. Stenosis and occlusion often require surgical or endovascular therapy
34
Q

Giant Cell Arteritis?

A
    • Chronic vasculitis
    • Large and medium-size vessels
    • Typically the temporal arteries
    • Associated with polymyalgia rheumatica
    • The large vessel type affects the aorta and its branches, particularly the subclavian arteries
    • Risk of dissection is greater in large vessel type and is associated with a poor prognosis
35
Q

Marfan Syndrome?

A
    • Autosomal dominant inherited connective tissue disorder
    • Mutations in the fibrillin gene (FBN1)
    • Fibrillin is responsible for the structural integrity and elastic tension of the vascular wall
    • Mutation results in elastic fiber fragmentation, structural disintegration, and aneurysms
    • Aneurysms occur at a younger age, enlarge faster, and lack calcifications or thrombus
    • Ascending aorta ++
    • Rapid onset and progression distinguish it from idiopathic medial degeneration
    • DIssection is common and can be recurrent
    • Dural ectasia is characteristic neurological manifestation
36
Q

Common complications of Marfan Syndrome?

A
    • Annuloaortic ectasia
    • Aortic dissection
    • Pulmonary artery dilation
    • Mitral valve prolapse

Doenças Cardiovasculares (47 decks)

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