2004 Radiology Exam - Thorax Case 1

Objective of the Case
To identify and logically deduce the location and origin of a mass in the caudal thorax.

Information Provided to Candidate

  1. Signalment: 5 week old male Great Dane
  2. History: 1-week history of regurgitation and recent onset of respiratory distress
  3. Lateral and dorsoventral radiographs of the thorax are available.
  4. State the radiographic findings.
  5. What is your assessment of these findings?
  6. Are further imaging studies needed? If so, what are they and why? If no, why not?

See images below. Click to enlarge.

Findings Expected from Candidate
There is a large, soft tissue mass in the caudal-dorsal region of the thorax, which is primarily on midline. There is gas distension of the esophagus cranial to the mass creating a gas/soft tissue interface as well as ventral displacement of the trachea due to the mass effect. The candidate was also expected to note the decreased visceral detail in the abdomen and the lack of a gas pattern in the region expected for the stomach.

Conclusion Expected from the Candidate
The most likely location of the mass is the mediastinum and likely the esophagus given the position, gas dilation of the esophagus and gas/soft tissue interface of the mass as well as the ventral displacement of the trachea. The most likely diagnosis is a gastroesophageal intussussception given the findings within the thorax as well as a lack of visualization of the stomach and the clinical history. No further imaging studies were indicated although no points were deducted if the candidate wanted to administer a small amount of contrast to verify stomach position.

Summary of Overall Candidate Performance
The candidates that were most successful on this case were methodical in their evaluation and were careful to evaluate the entire radiograph, which allowed them to be confident in identifying this as a gastroesophageal intussussception. Unsuccessful candidates focused on the mass effect and neglected to evaluate the rest of the radiograph and therefore they found it difficult to be confident of the etiology and location of the soft tissue mass effect.