Diagnostic Imaging: Principles, Thoracic 1 and 2 Flashcards

1
Q

Order the following from most radiopacity to most radiolucent?:

  • Soft tissue
  • Fat
  • Mineral/bone
  • Air
  • Metal
A

Most radiolucent-

  • Air
  • Fat
  • Soft tissue
  • Mineral/bone
  • Metal

Most radiopacity-

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2
Q

How should radiographs be approached?

What are the different radiograph signs observed for?

A

Systematic approach- evaluated systemically and identified for abnormalities described in terms of radiographic signs

Signs- shape, number, size, location, opacity

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3
Q

What is basic interpretation?

A
  • Deviation from normal appearance recognises
  • Lesion accurately described in systemic fashion
  • Pertinent aspects of lesion appreciated from their description
  • Formulation of DDXs
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4
Q

What should be radiographically appraised?

A
  • Ensure study is of correct patient and required regions imaged
  • Ensure study is complete- two orthogonal views
  • Identify views and check the labelling
  • Assess the technical quality of the image- exposure, climate, collimation, positioning, contrast, artefacts
  • Ensure you have previous relevant exams
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5
Q

What are the different search techniques?

A

System based- evaluate all systems present

Hypothesis-driven- use history/results- increased chance of mistakes (bias)

Mneumonic approach- ABCDE muscular skeletal (alignment, bones, cartilage/joints, devices, everything else)

Inside out, outside in

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6
Q

How does a description need to be systematically done?

A
  • Number- number of masses- simple but important, could be the major abnormality
  • Size- measurement diameter- be accurate, relative size can suffice- heart to thoracic vertebrae
  • Shape- rounded smooth- overall shape, margins, definition of margins
  • Location- cranial, caudal etc- use of anatomical landmarks when possible, can be more general
  • Opacity- soft tissue opacity- 5 basic opacity, soft tissue not distinguishable from fluid- unless we use contrast

Consider the possibility that lesion is an artefact of poor positioning

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7
Q

What is the mass effect?

What is effacement?

A

Mass effect- if something changes in size it will affect its surroundings, enlarged heart, dorsal trachea

Effacement- more complex than simply obscured- loss of normal contrasting opacity and so borders are lost, serosal detail (fat) allows visualisation of different structures in abdomen

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8
Q

What are the limitations of anatomical imaging?

A

2D representation of 3D structures

That’s why 2 views are needed at 90 degrees- orthogonal views

Only anatomical- not a definitive diagnosis- great for foreign bodies, fractures, ectopic ureters, hernias, calculi

Only a snapshot in time

Doesn’t show anything to do with functionality

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9
Q

What are the indications for a thoracic image?

A
  • Coughing
  • Dyspnea
  • Regurgitation
  • Cardiac disease
  • Tumour hunt
  • Trauma
  • Weight loss
  • Chest wall abnormalities
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10
Q

Why can normal radiographs not mean there is no disease?

A
  • PTE
  • Acute viral pneumonia
  • Acute and chronic tracheobronchitis
  • Lungworm
  • Upper airway disease
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11
Q

Describe the radiographic technique for a thoracic image?

A
  • Prevent rotation
  • Wedges under sternum
  • Assess costochondral junctions and where ribs articulate
  • GA vs Sedation
  • GA atelectasis- the collapse of lung lobe
  • Keep in sternal recumbancy
  • Always take dorsoventral first
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12
Q

How should thoracic radiographs be interpreted?

A

Assess radiograph overall- quality, phase of respiration, body condition

Systemic approach- many blind spots- ribs, mediastinal disease, tracheal disease

Normal or abnormal- many anatomical variants, use radiographic signs

Effects of recumbency- different positions of diaphragmatic crura in left vs right lateral, cardiac silhouette differs

BCS- widespread mediastinum, increased apparent opacity of lungs

Species differences-
psoas muscles in cats- caudal lung lobes don’t fully fille the space and makes them look smaller
differences in cardiac shape

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13
Q

What are the different lobes of the lung?

A

Right- cranial, medial, caudal, accessory

Left- cranio-cranial, cranio-caudal, caudal

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14
Q

What is abnormal about these three radiographs?

A

Left- decreased opacity

Middle- normal (lol)

Right- increased opacity

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15
Q

After determining opacity what needs to be assessed?

What can be identified with increased and decreased opacity?

A

Determine whether the change is pleural, mediastinum and lungs

Decreased opacity-
pleural space- pneumothorax
air within pleural space, retraction of lungs (atelectasis), evaluation of the cardiac silhouette

Increased opacity- increased fluid or loss of air
rule out artefacts- technique, obesity
increased opacity is often the abnormality
increased fluid/cells and/or loss of air

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16
Q

What needs to be assessed regarding different thoracic boundaries?

A

Normal sternum and spine

Mass, gas or thickening of soft tissues

Assess each rib individually- ribs normal in number, shape, opacity, size and position

Consider- degenerative, congenital, trauma, infection, neoplasia

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17
Q

What are thoracic wall masses often associated with?

A
18
Q

What can be seen with a pleural space effusion?

A

Border effacement- heart and diaphragm

Pleural fissures- fluid between lung lobes

Retraction of lung margins from the chest wall

May mask underlying pathology- masses

19
Q

What is in the mediastinum?

How are masses classified according to location?

What are the most common places for masses?

A

Mediastinum- trachea, oesophagus, heart and vessels, sternal lymph node

Location- cranioventral, central, craniodorsal etc

Most common location- lymph nodes, thymus

20
Q

What can cause decreased lung opacity?

What can the different causes be with diffuse, focal and apparent decrease in opacity?

A
  • Increased gas
  • Decreased soft tissue/fluid

Diffuse-
artefact, hypovolemia, hyperinflation

Focal-
cavitary lung lesion, emphysema, thromboembolus

Apparent-
pneumothorax, pneumomediastinum, subcutaneous emphysema

21
Q

What can cause lung volume increase/decrease?

What is a mediastinal shift?

A

Volume Increase- swelling/mass
Volume Decrease- collapse/atelectasis

Mediastinal shift- example of the mass effect-
mass/swelling pushes mediastinum away
collapse pulls mediastinum toward it

22
Q

Decide where from caudodorsal, generalised and cranioventral the following lesions appear?:

Oedema
Atelectasis
Pneumonia
Bronchitis

A

Caudodorsal- oedema, haemorrhage, atelectasis

Generalised- haemorrhage, metastatic neoplasia, atelectasis, oedema, fibrosis, bronchitis

Cranioventral- pneumonia, haemorrhage, atelectasis

23
Q

What are the 4 lung patterns?

A

Bronchial pattern

Vascular pattern

Interstitial pattern

24
Q

What causes a bronchial pattern?

How does it appear?

What are the DDXs?

What is bronchiestasis?

A

Increased visibility of bronchial walls- thickened or increased opacity

Appears as ‘tramlines’ and ‘donuts’

DDXs-
calcification- increased opacity
chronic bronchitis- allergic, irritant, parasitic
peribronchial cuffing- oedema, PIE/EBP, pneumonia, neoplasia

Bronchiectasis-
lack of tapering, widening bronchi
implicated chronic and severe disease

25
Q

What causes alveolar pattern of lungs?

How does it appear?

What are the DDXs for diffuse and focal?

A

Cells ± fluid replaces air the alveoli

Increased lung opacity, border effacement of adjacent structures, air bronchograms, lobar if entire lobe effects

DDXs-

Diffuse-
pneumonia, oedema, haemorrhage

Focal-
pneumonia, oedema, haemorrhage, primary/secondary tumour, lobe collapse, infarct, lung lobe torsion

26
Q

What causes an interstitial pattern?

What are the most common causes?

What are the DDXs for genuine diffuse?

What can cause a nodular interstitial pattern?

What are the potential pitfals?

A

Cells or fluid in interstitial tissue- blood vessels less distinctly seen

Most commonly artefactually- expiration, obesity, underexposure

DDXs- artefact, ageing, lymphoma, diffuse metastases, pneumonitis

Nodular- secondary neoplasia is most common, artifactual also common
nodules need to be 4-5mm and surrounded by aerated lung

Pitfalls-
pulmonary osteoma (mineralised and irregular)- older dogs normal
end on blood vessels
skin masses (nipples)

27
Q

What is the cardiac silhouette?

How does forwards heart failure lead to reduced cardiac output?

What does right and left backwards heart failure lead to?

A

Summation of the heart, pericardial contents and pericardium

Forwards heart failure leads to reduced cardiac output

Right backwards heart failure- vena cava congestion- ascites

Left backwards heart failure- pulmonary congestion/oedema

28
Q

Left vs right lateral recumbency affects the shape of the cardiac silhouette

Which image shows right/left lateral recumbency?

A

Left is right image

Right is left image

29
Q
A

Thought its useful to look at

30
Q

What is a vertebral heart score?

What is normal in dogs and cats?

A

Compare the size of the silhouette (sum of short and long axis) to the vertebral length

Dogs- 9.7 ± 0.5

Cats- 7.5 ± 0.3^2

31
Q

How can left-sided heart disease be seen on a radiograph?

A

Tracheal elevation from left ventricular enlargement

Straightening of the caudal cardiac border- left ventricular enlargement

Left atrial enlargement or ‘tenting’

May see bronchial compression cudal to carina

Divergence of caudal mainstem bronchi to more than 60-90 degrees

32
Q

What are the signs of right-sided heart disease on a radiograph?

A

Increase in cardiac width and rounding of right size

Increased R:L ratio

Increased sternal contact- beware of obesity

Reverse D on Dorsoventral view

33
Q

What pulmonary vessels can be evaluated in dogs and cats?

How big/small should they be?

A

Cranial and caudal lobar vessels can usually be elevated in cats and dogs

Usually not significantly wider then proximal 3rd of the 4th rib

34
Q

What is seen in a dog and cat radiograph with cardiogenic pulmonary oedema?

A

Interstitial (early/mild) or alveolar (late/severe) perihilar/caudodorsal predisposition

Left-sided cardiomegaly is often apparent

Maybe pulmonary vascular enlargement

Cats-
much more variable distribution
often patchy interstitial/alveolar pattern
cats with predominantly left-sided failure may develop pleural effusion

35
Q
A
36
Q

What type of dogs are more prone to mitral valve disease?

What is the typical pattern on a radiograph?

What happens when in failure?

A

Tends to be smaller dog breeds

Typical pattern of progressive left atrial enlargment

Ultimately pulmonary oedema

37
Q

What dogs are more affected by dilated cardiomyopathy?

What is seen on a radiograph?

A

Often large breed dogs

Often significant if clinical- less obvious if deep-chested

Significant left atrial ± right-sided enlargement

38
Q

What are the different cardiomyopathies in cats?

Which is the most common?

Why is generalised cardiomegaly usually seen?

A

Hypertrophic (HCM)- most common

Dilated (DCM)

Restrictive (RCM)

Unclassified (UCM)

chamber enlargement is not specific in cats- more generalised

39
Q

What is pericardial effusion?

What causes it?

How does it appear on a radiograph?

A

Fluid within the pericardial space

Can be idiopathic or secondary to masses

Round sometimes well-defined cardiac silhouette
Generally no-specific chamber enlargement evident
Subtle evidence of cause may be apparent

40
Q

What are the different common cardiovascular congenital diseases?

How doe they appear on a radiograph?

A

Pulmonic stenosis- stenosis of pulmonary artery
can see post-stenotic bulge, right-sided hypertrophy (backwards D)

Patent ductus arteriosus-
Increased pulmonary flow- left-sided enlargement and aortic enlargement

Persistent right aortic arch-
Most common vascular ring anomaly
left displacement of the trachea and deviation of left consistent sign, megaoesophagus

Peritoneal-pericardial diaphragmatic hernia

41
Q

What can hypovolaemia result in?

A

Results in micro-cardia and hypo-vascular lungs