Canis ISSN: 2398-2942

Radiology: lungs

Contributor(s): Fraser McConnell

Introduction

Overview

  • Radiography allows assessment of lung size, position and density.

Radiographic considerations

  • The lateral projection is often used as a sole projection for thoracic radiography but this in fact provides poor detail of the dependent lung.
  • If lateral projections are used, eg in the identification of pulmonary metastases, both laterals should be taken.
  • Orthogonal views should be taken to locate the 3-dimensional position of a lesion.
  • Ventrodorsal projections allow better visualization of the lung fields (especially accessory lobe) than the DV.
  • The lung fields provide an inherent contrast within the thorax - a high KVp mAs should be used to maximize the range of densities available of pulmonary radiographs.
    Use as short an exposure time as possible to minimize movement blur.
  • A grid is necessary if the depth of tissue is >10 cm.
  • Exposure is normally made at the point of maximal inspiration.
  • Expiratory films are occasionally useful to document small pneumothoraces, air trapping and bronchial and tracheal collapse.
  • Care should be taken to include the entire pulmonary field.

Restraint

  • Examination is normally performed under sedation but heavily sedated animals may have poor inspiratory volumes making it impossible to obtain a view of a truely inflated lung.
  • The VD projection should be avoided if there is a large volume of pleural fluid.
    Most dyspneic animals will lie quietly in sternal recumbency for a DV projection with minimal restraint and no sedation.Stressful handling of dyspneic animals may result in fatal decompensation.

Indications

  • Dyspnea.
  • Chronic cough.
  • Screening for metastasis in the presence of malignant neoplasms elsewhere.
  • Hemoptysis.
  • Pre-anesthetic check.
  • As part of minimum database in the investigation of many medical conditions.
  • Ultrasonography is often more valuable than radiography in the presence of pleural fluid.
    Dyspnea in the face of normal thoracic radiographs should prompt consideration of upper airway obstruction Brachycephalic airway obstruction syndrome , paraquat poisoning Paraquat poisoning , pulmonary thromboembolism Lung: pulmonary thromboembolism and acute viral pneumonia Lung: bacterial pneumonia.Not all serious lung pathology will result in radiographic abnormalities.

Radiographic anatomy

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Interpretation

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Additional studies

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Nykamp S G, Scrivani P V & Dykes N L (2002) Radiographic signs of pulmonary disease: an alternative approach. Comp Contin Educ Pract Vet 24 (1), 25-35 VetMedResource.
  • Lamb C R & Neiger R (2000) Radiology corner - differential diagnosis of pulmonary cavitary lesions. Vet Rad Ultra 41 (4), 340-341 PubMed.


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