Introduction

Overview

• See radiography: thorax Radiography: thorax for details of positioning technique.
• Radiography allows assessment of lung expansion and density and the thoracic wall.

Radiographic considerations

• The dorsoventral projection is often the most useful for identifiying pathology involving the chest wall, and pleural and mediastinal spaces.
• The lateral projection is often used as a sole projection for thoracic radiography but this in fact provides poor detail of the dependent lung.
• Orthogonal views should be taken to locate the 3-dimensional position of a lesion.
• Oblique views may be required to highlight or skyline a lesion - particularly chest wall swellings where an oblique is useful to skyline the suspected lesion.
• 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.
• Rare earth screens, preferably fast screens, are required for medium to large dogs.
• Use of a grid will provide better images if the depth of tissue is > 10 cm.
  If the X-ray machine is low-powered it may not be possible to achieve a sufficiently short exposure time with a grid and image quality may have to be sacrificed.
• Exposure is normally made at the point of maximal inspiration to provide the most contrast within the thorax but this will depend on the lesion under examination.

Restraint

• Examination is normally performed under sedation.
• Particular care is required with dyspneic animals.
  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.
• Trauma.
• Evaluation of masses adjacent to the chest wall.
• As part of minimum database in the investigation of many medical conditions especially FUO, neoplasia, ascites.
• Regurgitation.
  Ultrasonography often more useful than radiography in the presence of pleural fluid.

Radiographic anatomy

Interpretation

Pit falls

Additonal studies

Further Reading

Publications

Refereed papers

• Recent references from PubMed and VetMedResource.
• Lamb C R (2000) Ability to visualize the cardiac silhouette in animals with pleural fluid: the pericardial fat stripe. Vet Rad Ultra 41 (6), 519-520 PubMed.
• Fossum T W, Evering W N, Miller M W et al (1992) Severe bilateral fibrosing pleuritis associated with chronic chylothorax in five cats and two dogs. JAVMA 201 (2), 317-324 PubMed.
• Fossum T W, Boudrieau R J & Hobson H P (1989) Pectus excavatum in eight dogs and six cats. JAAHA 25 (5), 595-605 VetMedResource.