Transcript Introduction to Thoracic Radiology

Introduction to Thoracic
Radiology
Dr. LeeAnn Pack
Dipl. ACVR
Indications
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Coughing
Dyspnea/ Tachypnea
Heart Murmur, Collapse
Primary or Secondary Neoplasia
– Check for metastasis
• Thoracic Trauma
• Chest Wall Mass
• Exercise Intolerance, Weight Loss
Technical Factors
• Potential for Movement
– Decrease mAs
• High inherent contrast
area
– High kVp
• Collimation
• Centering – caudal
scapula
– Thoracic inlet to
diaphragm
– Pull forelimbs forward
Determining the Phase of
Respiration
• Always expose at peak inspiration
– Maximizes lung contrast
– Inspiratory lateral view
• Caudodorsal aspect of lung caudal to T12
• Increased aeration of accessory lung lobe
• Separation of heart silhouette and diaphragm
– Inspiratory VD/DV view
• Diaphragmatic cupola caudal to mid T8
• Lung tips caudal to T10
Inspiratory vs. Expiratory Lateral
Note the space inside the
triangle
Inspiratory vs. Expiratory VD
Easy to see the difference in well
visualized lung
DV vs. VD
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Less stressful, better for heart
Diaphragm rounded
Caudal pulmonary vessels better visualized
Better to see small amount of pleural air
• VD
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Better for lungs
Hear appears elongated
Flat diaphragm – Mickey Mouse ears
Better to see small amount of pleural fluid
DV vs. VD
Right vs. Left Lateral etal.
• Right Lateral
– Better cardiac detail
– R crus forward
– See Cava go into it
• Left Lateral
– Heart appears round
– L crus forward
– See Cava go past
• Anesthesia
• Breed Differences
The Effects of Lateral
Recumbency
• Lung lesions (mass, nodule, infiltrate)
may only be seen on 1 view!!!
• Only the non-dependent (up) lung can
be critically evaluated
– Dependent lung loses aeration
(atelectasis)
• Increases in opacity
• Silhouettes with lesions
Interpretation of Thoracic
Radiographs
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Heart
Lungs
Mediastinum
Pleural space
Chest wall
Bones, Abdomen,Neck
Normal Cardiac Silhouette
• Subjective
– Dog = 2 ½ - 3 ½ intercostal spaces
– Cat = 2 – 2 ½ intercostal spaces
• 65% or less on VD/DV view
• Objective
– Buchanan method
Clock Face
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11-1 Aortic Arch
1-2 Main Pulmonary Trunk
2-3 Left Auricle
2-5 Left Ventricle
5-9 Right Ventricle
9-11 Right Atrium
Centrally – Left Atrium
Lateral View
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Make a Plus sign
Bermuda triangle
Left atrium
Left Ventricle
Right Ventricle
Thoracic and Pulmonary
Vessels
• Aorta
• Caudal Vena Cava
• Cranial pulmonary
vessels
– Proximal third rib
• Caudal pulmonary
vessels
– 9th rib where crosses
• Veins are ventral and
central
Trachea, Bronchial Tree
• Carina – then splits to the main stem
bronchi then lobar bronchi
• Tracheal rings can mineralize
• Decreased tracheal diameter
– Tracheal narrowing (stenosis, extramural
compression), Tracheal hypoplasia,
Tracheal collapse
Lungs
• Normal anatomy
– Left
• Cranial (cranial
subsegment)
• Cranial (caudal
subsegment)
• Caudal
– Right
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Cranial
Middle
Caudal
Accessory
The Mediastinum
• Cranial, middle, caudal compartments
• Routinely visible structures:
– Heart, trachea, cvc, aorta, +/- thymus, +/esophagus
– Cranioventral mediastinal reflection
– Caudoventral mediastinal reflection
• Aka phrenopericardiac ligament
Mediastinal reflections
Extrathoracic Structures
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Sternum
Vertebrae
Ribs
Adjacent soft
tissues
• Diaphragm
The Diaphragm
• Cupola
– Cranioventral convex
portion
• Right and left crura
– Attach to cranioventral
border of L3 and body of
L4
– May cause irregularity on
these surfaces
• Appearance depends on
centering of X-ray beam
The Diaphragm