Dr. LeeAnn Pack
Dipl. ACVR

• Coughing
• Dyspnea/ Tachypnea
• Heart Murmur, Collapse
• Primary or Secondary Neoplasia
– Check for metastasis
• Thoracic Trauma
• Chest Wall Mass
• Exercise Intolerance, Weight Loss

• 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

Easy to see the difference in well visualized lung

• DV
– Less stressful, better for heart
– Diaphragm rounded
– Caudal pulmonary vessels better visualized
– Better to see small amount of pleural air
• VD
– Better for lungs
– Hear appears elongated
– Flat diaphragm – Mickey Mouse ears
– Better to see small amount of pleural fluid

• 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
• Heart
• Lungs
• Mediastinum
• Pleural space
• Chest wall
• Bones, Abdomen,Neck

• Subjective
– Dog = 2 ½ - 3 ½ intercostal spaces
– Cat = 2 – 2 ½ intercostal spaces
• 65% or less on VD/DV view
• Objective
– Buchanan method

• 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

• Make a Plus sign
• Bermuda triangle
• Left atrium
• Left Ventricle
• Right Ventricle

• Aorta
• Caudal Vena Cava
• Cranial pulmonary vessels
– Proximal third rib
• Caudal pulmonary vessels
– 9 th rib where crosses
• Veins are ventral and central

• 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

• Normal anatomy
– Left
• Cranial (cranial subsegment)
• Cranial (caudal subsegment)
• Caudal
– Right
• Cranial
• Middle
• Caudal
• Accessory

• Cranial, middle, caudal compartments
• Routinely visible structures:
– Heart, trachea, cvc, aorta, +/- thymus, +/esophagus
– Cranioventral mediastinal reflection
– Caudoventral mediastinal reflection
• Aka phrenopericardiac ligament

• Sternum
• Vertebrae
• Ribs
• Adjacent soft tissues
• 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