2008 Radiology Exam - Thorax Case 2

Candidates were presented with orthogonal views of the thorax of an 8 month old female Rottweiler with a history of regurgitation and vomiting.

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• Candidates were expected to identify widening of the cranial mediastinum due to focal gas and fluid distension of the esophagus from the heart base cranially. The candidates were expected to describe focal ventral and leftward deviation of the trachea as well as focal attenuation of the tracheal lumen at the level of the heart base. A note regarding lack of any signs of aspiration pneumonia was also warranted.
• From these observations, candidates could then diagnose vascular ring anomaly as the most likely cause of the findings. Because of the focal leftward deviation of the trachea on the VD projection, vascular ring anomaly due to persistent right fourth aortic arch (PRAA) was to be described. Other less likely vascular ring anomalies could be listed but primary focus was PRAA based on prevalence and radiographic findings.
• In order to further evaluate the findings, candidates chose primarily espophagram and/or CT angiography. Esophagrams were chosen to confirm the focal dilation and to assess for potential changes in motility. CT angiography was chosen to evaluate specific vascular anomalies.
• Overall, candidates performed very well on this question. Most candidates received either a 9 or 10 out of 10 total points. A failing score was given if congenital megaesophagus was the primary or only differential diagnosis listed. A number of candidates were somewhat perplexed by the high contrast of the digital radiograph presented on film. This resulted in describing a bronchial pattern when there was not one. Some candidates incorrectly diagnosed bronchopneumonia as a result of describing the bronchial pattern.