Small Animal Thorax Lavin: Chapter 19

Objectives: Thorax Correctly & safely position a dog or cat for various thoracic views Be able to describe common and alternate thoracic views ID normal thoracic radiographic anatomy

Skeletal Anatomy Review

Thoracic Viscera: Anatomy Review

Small Animal Thorax: Considerations Indications for radiography: Normal views: Lung disease - VD, both left & right lateral Cardiac – DV, right OR left lateral Metastasis – VD or DV, both left & right lateral “Met check” Oblique views may be necessary

Thorax Views: Patient Prep Clean, dry fur No matted hair Remove collars and leashes Place in correct position on the table (Heel effect) Measure in the position they are to be radiographed in Thickest part is usually caudal aspect of scapula

Small Animal Thorax: Radiographic Concerns Settings: kVp: ______________ mA: ______ mAs: ______ Use highest mA and shortest time for mAs Mass or fluids suspected? May need to increase initial kVp by 10-15% Entire lung field must be included for film to be diagnostic ___________ __________ to May need to take two films to include all anatomy

Small Animal Thorax: Radiographic Concerns Expose at peak _______________ Maximizes air in lung fields Separates heart and diaphragm Can be synchronized with PPV if intubated Control panting! Blow in face, hold mouth shut Exception: Vet may request on expiration when looking for fluid or air in the plural space

Lateral Thorax: Considerations Entire ribcage should be included Place markers at ventral aspect Pull forelimbs as far cranially as possible Do not allow rotation! All anatomy parallel to cassette If lung lesions are suspected: best seen when placed ___________ from Image receptor.

Lateral Thorax: Considerations Collimation: Cranial margin- scapulohumeral articulation (_________ _________) Caudal margin- first __________ vertrbral body This places central beam directly over the heart Look for superimposition! *Normal sized heart = 2.5 - 3.5 times width of ______________ space

Confirming Central Line Placement

Metastasis

Pleural Effusion

Pulmonary Edema

Dorsoventral Thorax: Considerations DV is best view for: Heart Pulmonary arteries/veins Center directly over heart Include cranially from shoulder joint, caudally to diaphragm Pull forelimbs cranial and try to rotate paws inward Ensure patient is straight with no rotation! Symmetry!

Heartworm Disease “D” shaped heart

Ventrodorsal Thorax: Considerations Best for: Lungs Mediastinum Measure over the caudal border of the scapula Difficult view in dyspneic patients Symmetry!

Pneumothorax

Metastatic Lungs

Other Thorax Views Lateral decubitus DV decubitus Standing lateral view Used when looking for fluid-gas margins or traditional views cannot be tolerated

Thoracic Anatomy: Review Four anatomic regions of the thorax: Extrathoracic Skeleton and diaphragm Pleural space Contains lungs Separates lungs from body wall Contains small amount of fluid not visible on radiograph Pulmonary parenchyma Lung lobes, bronchi, bronchioles, alveoli

Thoracic Anatomy: Review Mediastinum The space between the lungs Contains the trachea, esophagus, heart, aorta, and various nodes, ducts, and nerves “Cardiac silhouette” Divides thorax into right & left sides

Other Thoracic Structures Esophagus Usually not noted on radiographs Unless highlighted by feeding tube, food, or is enlarged Trachea – Air-filled Usually ___________ to esophagus Towards right on lateral

Small Animal Thorax

Small Animal Thorax