Introduction to Introduction to Thoracic Radiology Thoracic Radiology Dr. Meghan Woodland September 30, 2010.
Dec 14, 2015
Introduction to Thoracic Introduction to Thoracic RadiologyRadiology
Dr. Meghan Woodland
September 30, 2010.
Indications
• 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– Respiration– Decrease mAs
• High inherent contrast– High kVp
• Collimation– Should include thoracic
inlet to diaphragm
• Center over the heart• Pull thoracic limbs
forwardRadiographic techniques: the dog
By Joe P. Morgan, John Doval, Valerie Samii
Determining the Phase of Respiration
• Always expose at peak inspiration– Maximizes lung contrast– Better visualization of pulmonary parenchyma– Less compression of lungs by diaphragm
• Inspiratory lateral view:– Caudodorsal aspect of lung is caudal to T12– Increased aeration of accessory lung lobe– Separation of cardiac silhouette and diaphragm
• Inspiratory VD/DV view:– Diaphragmatic cupola caudal to mid-T8– Tips of lung caudal to T10
Inspiratory vs. Expiratory Lateral
Notice size of triangle
Inspiratory vs. Expiratory VD
Easy to see the difference in well visualized lung
DV vs. VD
• DV– Best view to evaluate cardiac silhouette and caudal
pulmonary vessels– Less stressful for the patient – Diaphragm rounded– See small amounts of pleural air
• VD – Best view to evaluate lungs– Heart appears elongated– Flat diaphragm – Mickey Mouse ears– See small amounts of pleural fluid
DV VD
DV vs. VD
Right vs. Left Lateral
• Caudal Vena Cava enters the right diaphragmatic crus
• Right Lateral– Better cardiac detail– R crus forward
• See CVC go into it
• Left Lateral– Heart appears round– L crus forward
• See Cava go pastCaudal vena cava
Left or Right Lateral?
Left or Right Lateral?
The Effects of Lateral Recumbency
• Lung lesions (mass, nodule, infiltrate) may only be seen on a single view
• Only the non-dependent (up) lung can be critically evaluated– Dependent lung loses aeration
(atelectasis)• Increased opacity• Silhouettes with lesions
Sedation Induced Atelectasis
Interpretation of Thoracic Radiographs
• Systematic approach is crucial
• Heart (Cardiac Silhouette)
• Lungs
• Mediastinum
• Pleural space
• Chest wall
• Bones, Abdomen, Neck
Normal Cardiac Silhouette• Size is subjective• Lateral views:
– Dog = 2 ½ - 3 ½ intercostal spaces– Cat = 2 – 2 ½ intercostal spaces
• VD/DV views:– 65% the width of the thorax
• Objective:– Buchanan method
• Vertebral heart scale
Clock Face
• 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
• Make a Plus sign• Bermuda triangle
– Right atrium– Main pulmonary artery– Aortic Arch
• Left atrium• Left Ventricle• Right Ventricle
Thoracic and Pulmonary Vessels
• Aorta• Caudal Vena Cava• Cranial pulmonary vessels
– Proximal third rib
• Caudal pulmonary vessels– Where crosses 9th rib
• Veins are ventral and central– Artery, bronchus, vein– ABV’s
Trachea, Bronchial Tree
• Trachea ends at the carina• Then splits to the main stem bronchi followed
by the lobar bronchi• Tracheal rings can mineralize (age)• Decreased tracheal diameter
– Tracheal narrowing (stenosis, extramural compression)
– Tracheal hypoplasia– Tracheal collapse
Lungs
• Normal anatomy– Left
• Cranial (cranial subsegment) 1
• Cranial (caudal subsegment) 2
• Caudal 3
– Right• Cranial 4
• Middle 5
• Caudal 6
• Accessory 7
1
2
3
4
5
6
7
The Mediastinum
• Cranial, middle, caudal compartments
• Routinely visible structures:– Cardiac silhouette, trachea, caudal vena
cava, aorta, +/- thymus, +/- esophagus– Cranioventral mediastinal reflection– Caudoventral mediastinal reflection
• Aka phrenopericardiac ligament• Left side on VD radiograph
Mediastinal Reflection
Caudoventral mediastinal reflection
Extrathoracic Structures
• 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
The End