2008 Radiology Exam - Thorax Case 1

Information Provided to the Candidate

A 9 year old female mixed breed dog presented for seizures. The dog was febrile at the time of admission.

Left lateral and ventrodorsal radiographs of the thorax are available.

  • State your radiographic findings
  • What is your radiographic diagnosis or prioritized differential diagnosis list based on radiographic findings?
  • What further imaging studies or diagnostic tests are indicated to reach a more definitive diagnosis? If so, what are they and why? If no, why not?

See images below. Click to enlarge.

Candidate received points for:
Describing enlargement of the main pulmonary artery segment on the vd view. Identifying enlarged peripheral pulmonary arteries and describing the tortuous appearance of the vessels with mild perivascular interstitial opacity evident on the lateral view in the caudal dorsal lung fields. Characterizing the cardiac silhouette as normal or showing evidence of mild right sided cardiac enlargement. Describing mildly dilated gas filled loops of bowel in the cranial abdomen, reduced serosal detail and abdominal distension.

Radiographic diagnosis: Heartworm infection, or less likely pulmonary hypertension. Possible abdominal mass and/or peritoneal fluid and functional or mechanical ileus.

Next step: Heartworm testing, echocardiogram with Doppler evaluation of the pulmonic and tricuspid valves to assess pulmonary artery pressure if heartworm testing was negative. Abdominal radiographs +/- abdominal US to further characterize the abdominal changes. (Final diagnosis via necropsy was heartworm infection, large uterine cyst, uterine leiomyoma, secondary moderate volume peritoneal effusion, seizure secondary to presumptive heat stroke)

Candidate performance: This was a discriminating question and some candidates did not recognize enlarged peripheral pulmonary arteries or the enlarged MPA, or described the enlarged MPA but concluding the prominence was secondary to positioning artifact. Candidates who performed poorly mistakenly concluded the large nipple shadows present overlaying the lung in this patient were pulmonary nodules secondary to neoplasia or granulomatous disease. Most candidates recognized and were concerned about possible significant abdominal changes and appropriately recommended abdominal radiographs.