Thoracic X-Ray in cardiac patients. Questions and images provided by Dr Franck Durieux, Dip ECVDI - Aquivet.

Correct. The contrast of the image will be better because the grey shadow from the scattered radiation will be stopped by the grid lines. You will have to increase the quantity of x-ray to compensate the attenuation of the X-ray beam through the grid (In general, mAs should be doubled for a 8 grid factor).

Correct. These two views allow a complete examination of the pulmonary area and cardiovascular structures. The ventrodorsal (VD) view enables a larger view of the pulmonary area but is less physiological than the ventrodorsal view and can cause artefactual chamber enlargement. Also, beware of cases with major pleural effusion when respiration of the animal could be made more difficult or even dangerous with the DV view. In general, the left lateral view is made in addition to the right lateral view for dogs with very narrow chest wall for which DV views are almost impossible to make (or to read) and when a complete lung lesional checkup is needed.

Incorrect. When assessing the heart, the ventrodorsal view is less physiological than the dorsoventral view and can therefore cause artefactual chamber enlargement

Incorrect. This would be the most sensitive technique when looking for pulmonary metastasis. However, to assess the heart, a ventrodorsal view is also recommended.

Incorrect. Several sedation protocols are available which can be used very safely in our cardiac patients.

Incorrect. Sandbags can help to optimise patient positioning.

Incorrect. Leg ties and adhesive tape can help to optimise patient positioning.

Correct. General anaesthesia is no recommended as animals very quickly get pulmonary atalectasis, changes in heart shadow and chamber changes which might give a false interpretation

Correct. We can see the presence of an endotracheal tube. The lung's inflation under gas anaesthesia facilitates pulmonary consolidation and atelectasis.

Incorrect. We can see the endotracheal tube, showing the dog is under general anaesthesia.

Incorrect. The operators wear no protection against ionizing radiations on their hands. One of the operators even has his hands in the primary beam.

Incorrect. The operators wear lead gloves. However one of the operators has his hands in the primary beam. The lead gloves do not completely stop the ionizing radiation, hands must be kept as far as possible from the primary beam.

Correct. The operators wear lead gloves, and their hands are placed away from the primary beam reducing significantly the dose impact on the hands.

Incorrect. The left lateral view is often used for the examination of the pulmonary area.

Correct. On this image, the rib overlaps with the vertebrae (blue arrow). It indicates the view is oblique, which can have consequences on the perception of the cardiovascular and respiratory structures. This can give the impression of a false dorsal deviation of the trachea consistent with cardiomegaly or dorsal movement on the cardiac silhouette (orange arrow).

Incorrect, the limbs are indeed in extension - as they have to be in order to see the cranial zone of the thorax and in particular the mediastinal area.

Incorrect. The breastbone should be raised to have a perfect profile (or lateral) view. From a radioprotection point of view , it is necessary to limit the number of x-ray images!

Incorrect. The expiratory phase will not improve the position of the animal but will instead produce interstitial lung pattern, which can be a source of misinterpretation.

Correct. To remedy, you can simply place a block under the breastbone. It will have the effect of raising the thorax and reducing obliqueness. This is particularly true for subjects with a cylindrical thorax and large dogs with narrow thoracic cage.

Incorrect. An under exposed image would result in a very bright image without detail.

Correct. This X-ray image is blurred, the vascular structures are not sharp enough.

Incorrect, too high kVP would give an over-exposd and therefore darkened image.

Correct. Excitement/ respiratory distress syndrome can cause this type of movement blur.. Sedation may be necessary to reduce this.

Incorrect. Increasing exposure time will increase movement blur.

Correct. To minimise movement artefact use a minimum exposure time, low mAS and high KV.

Incorrect. The ventrodorsal, right lateral and left lateral are the best views for assessing respiratory or pulmonary disease.

Correct. This view is the most adapted for examination of the cardiovascular structures in combination with the right lateral view. In this "physiological" position, the abdominal organs rest ventrally on the diaphragm which pushes the apex of the heart cranially and to the left.