STEEPLECHASE RADIO - CARDIAC + THORACIC Flashcards
Thoracic radiography indications
- Coughing - pul disease, R-sided CHF, parasitic disease, neoplasia, inhaled FB
- Dyspnoea - airway obstruction, pul disorders, pleural disorders
- CVS disease - murmurs, CHF, arrhythmia - heart size
- Thoracic trauma - pneumothorax, haemothorax, rib Fx, diaphragmatic rupture
- Neoplasia - 1y, metastatic disease
- Regurg - megaoesophagus, FB, congenital disorders, differentiate between GI disease
- Thoracic wall lesions - neoplasia, thoracic deformity
Considerations (thoracic)
- Exposure - high kV, low mAs, minimise effect of movement blur
- Inspiratory view - full inspiration, when animal breathes in
- Don’t GA dyspnoeic animal - risk of lung collapse
Minimum orthogonal views (thoracic)
- Cardiac conditions = RL + DV (heart near x-ray plate)
- Lung path - RL+ VD (lungs flop to side + expand for visualisation)
- Pul metastases - RL, LL, VD
Dorsoventral pos (thoracic)
Ventrodorsal pos (thoracic)
Lateral recum pos (thoracic)
Included in thoracic radiograph
- Surrounding ST
- Cranial abdo + diaphragm
- Neck
- Bones + ribs
- Pleural space
- Mediastinum
- Trachea + carina
- Bronchi
- Cardiac silhouette
- Great vessels + pul vasculature
- Lungs
Mediastinum
- Space between L + R pleural cavities
- Extends from thoracic inlet to diaphragm
- VD/DV size = dog = < twice width of vertebral column; cat = no wider than width superimposed thoracic spine
- Present but not visible = azygos vein, main pul a., vagus n.
Cranial mediastinum
- Trachea
- Oesophagus
- Cranial VC
- Cranial mediastinal + sternal LNs
Middle mediastinum
- Heart
- Oesophagus
Caudal mediastinum
- Aorta
- Caudal VC
- Oesophagus
Medistinal shift
- Movement of the mediastinum or structures within away from the mid line (indicates a change in volume of one hemithorax)
- DV or VD projection
- Causes: unilateral lung collapse; pleural disease; unilateral pleural effusion or pneumothorax; large single or multiple pulmonary masses; unilateral diaphragmatic rupture
Cardiac sizing - dog
- On lateral view, cardiac length (base to apex) should be 70% of dorsal to ventral distance of thoracic cavity
- On lateral view, cardiac width should be 2.5 - 3.5 intercostal spaces
- On DV/VD view cardiac width is approx. 60 – 65 % of thoracic width
- Aorta - diameter approx. the height of the adjacent vertebra
- Vena cava diameter varies with intrathoracic pressure, disease, hypovolaemia
Cardiac sizing - cat
- On lateral view, cardiac width should be 2 - 2.5 intercostal spaces
- VD - approx 2/3 of width of thorax
How to take vertebral heart score
From a lateral thoracic radiograph:
- 1). Measure the long axis of the heart from the ventral border of the left main stem bronchus to the most distal ventral contour of the cardiac apex.
- 2). Transfer this measurement to the thoracic vertebrae - starting at the cranial margin of the 4th
thoracic vertebral body and progressing caudally - count the number of vertebrae to the nearest 0.1
- 3). Measure the short axis of the heart at the widest part of the cardiac silhouette, making a line perpendicular to the long axis
- 4). Transfer this measurement in the same way as for the long axis.
- 5). Add the two measurements to give the dog’s vertebral heart size.
VHS breed variations
Lateral thorax canine
Lateral thorax feline
VD thorax canine
VD thorax feline
VD thorax greyhound
Lateral thorax greyhound
VD thorax bulldog
Lateral thorax bulldog
How do you calculate the vertebral left atrial size?
- Draw line from centre of most ventral aspect of carina to caudal aspect of left atria (1)
- Second line equal length from cranial aspect of T4 (2)
- Count no. vertebrae
- > 2.3 LA enlargement
Abnormalities?
- Small cardiac silhouette - reduced in all dimensions
- Apex lifted from sternum
- Heart more triangular in shape
- Hypolucency of (dark) lung fields
- Cranial lobar artery/vein small in diameter (compare diameter at 4th i/costal space with diameter of prox 4th rib)
- Dx: Small cardiac silhouette + pulmonary vasculatur -> hypovolaemia associated with dehydration (Hypovolaemic shock, Addisonian crisis)
What abnormalities?
- Cardiac silhouette - globoid in shape
- Occupies > 70% of d/v thorax + > 3.5 intercostal spaces
- Trachea elevated
- Causes - generalised cardiomegaly (eccentric hypertrophy); pericardial effusion
- Differentiation: Ultrasound exam would differentiate
Trachea
- Lateral view - head in neutral pos so no artefacts
- Pos - angle w/ thoracic spine, parallel to spine in lateral, superimposed on spine in DV
- Size - should not change during resp cycle, narrowing in tracheal collapse - hard to Dx
Oesophagus
- Thoracic + cervical radiographs needed
- Dorsal mediastinum
- Can be air-filled in normal animal
- Tracheal strip = luminal air, seen w/ megaoesophagus
Lung views
- DV/VD first
- Lateral will cause atelectasis (collapse) of dependent lobe
Artificial inc in lung opacity
- Obesity
- Under-exposure
- Expiration
- Atelectasis
- Pleural disease
- WHITE
Genuine inc in lung opacity
- Reduction in air volume (air = radiolucent, black)
- Increase in soft tissue/fluid within lung
- Combination of both
Lung patterns
- Alveolar - alveoli filled w/ something other than air
- Interstitial - structured + unstructured
- Bronchial - tram lines + donuts
- Vascular
Alveolar lung patterns
- Always clinically sig
- Alveoli filled w/ oedema (cardiogenic oedema from heart disease or strangulation/electrocution), exudate, blood (trauma), neoplastic cells
- Inc lung opacity - patchy or homogenous, focal, multifocal, diffuse
- Border effacement - alveolar filling
- Air bronchograms - branching radiolucent lines over consolidated lungs
- Inc visibility of borders of individual lung loves - lobar sign - when alveolar pattern extends to periphery of lobar margin + lies adjacent to some aerated lungs
Alveolar lung patterns
(Air bronchogram = a pattern of air-filled bronchi on a background of airless lung)
Alveolar lung patterns - ventral
Aspiration pneumonia
Alveolar lung patterns - perihilar (wedge-shaped central portion of lung on medial aspect)
- Cardiogenic oedema
- +/- Enlarged heart
- Cardiogenic pulmonary oedema
Alveolar lung patterns - lobar
Lung lobe torsion
Alveolar lung patterns - caudodorsal
- Non-cardiogenic oedema
Alveolar lung patterns - peripheral
Angiostrongylus infection
Interstitial lung patterns - nodular
- Nodular ST opacities in lung - granulomas common in fungal disease
- Cannonball - neoplastic, ST w/ radiolucent centre
- Miliary pattern - small multiple coalescing nodules - neoplastic, ST opacities, CT more useful, can only see if 3 - 5 mm in diameter
- Solitary (nodular) - neoplasia, abscess, granular
Interstitial lung patterns - unstructured/reticular
- Diffuse swelling of interstitial space
- Common in WHWH w/ interstitial pul fibrosis
- Connective tissue - things look more opaque
- Oedema, H+, fibrosis, neoplasia, infection
Bronchial lung patterns
- 1). Tram lines
- 2). Donuts
- Thickening of bronchial walls
- Peribronchial changes from cellular infiltrate in interstitium - older animals w/ chronic bronchitis
- Can be seen in inflammatory conditions such as those from parasites, allergy or infectious agents e.g. feline lower airway disease e.g. asthma - concurrent hyperinflation + lungs inflated towards last rib
Lungs - pulmonary vessels
- Veins = ventral + central, drift away from bronchial wall towards lung periphery
- Arteries - close to a bronchus
- At same level, aa + vv should be same size
Lung patterns - vascular pathology
- Enlargement of pul vv = congestive HF
- Enlargement of pul aa = angiostrongylus, pul hypertension (R to L cardiac shunt / pul thromboembolism)
- Narrowing of vv = hypovolaemia (shock/haemorrhage)
Pleural space
- Not normally seen as potential space
- Due to pleural effusion = fluid in pleural space (inc radiopacity = (H+, exudate, transudate, chyle), masses or air (inc radiolucency)
- Most bilateral
- DV most sensitive for small effusions
- Retraction lung lobes from thoracic wall
- Widening of interlobar fissures
- Scalloped lung lobe borders
- Silhouette sign – heart partially or fully obscured
Causes of pleural effusion
- Congestive HF (cat)
- Pyothorax
- H+
- Chylothorax
- Haemothorax - trauma, coagulopathy
Pneumothorax - apex of heart lifted from sternum - radiolucency (air) outlining lungs
Lung interstitial pattern, diffuse = metastatic neoplasia
- Lung interstitial pattern = nodular, solitary lesion
- Neoplasia, abscess, granuloma
R lateral thorax of normal dog
- Unstructured interstitial lung pattern in a 3 m/o w/ mycoplasma pneumoniae
- Inc hazy appearance over caudodorsal lung fields
- Pulmonary vessels are visible but have fuzzy margins, giving the appearance of “trees in a fog”, that is an interstitial pattern
- Miliary metastasis from melanoma in a dog
- Extensive variably sized nodules coalesce to obscure resp + caridac detail
- Pleural plaques in dog
- Small, mineralised opacities too small to be pulmonary nodules
- Hypovascular lung pattern in hypovolaemic dog
- Small heart + small pulmonary vv as they cross fourth rib (red arrow)
- Cat - severe bronchopneumonia w/ alveolar pattern in cranial lung lobe
- Lobar sign + bronchograms (red arrows)
- Severe diffuse broncho-interstitial lung pattern in caudodorsal lung fields (green arrows)
- Cardiogenic oedema in cat
- Diffuse fluffy alveolar pattern - esp in caudodorsal lung lobes (red oval)
- Border effacement (sign of alveolar disease) obscures in cardiac outline (red arrow)
- Hyperlucent pattern in cat w/ severe lower airway disease + dyspnoea
- Flattened, caudal displacement of diaphragm (red arrow)
- Straightened ribs (green arrows)
- Bronchial tramlines + donuts (red oval)
- Cardiac silhouette appears enlarged (vertebral heart score = 13.5; normal 8.5 – 10.7) with a prominent bulge at the level of the left atrium particularly visible in the lateral view.
- Trachea is parallel with the thoracic spine, suggesting elevation, and is slightly compressed.
- Caudal vena cava is also angling upwards.
- The pulmonary vasculature is quite prominent.
- Evidence of pulmonary venous congestion and an interstitial pattern consistent with pulmonary oedema
- Respiratory system: peribronchial pattern throughout the caudodorsal and mid lung fields that could also be related to pulmonary oedema
- ATRIAL FIBRILLATION
