The lowest scoring case on the Thorax section of the 2016 certifying examination was a two view radiographic study of canine heartworm disease with moderate to severe associated pneumonitis in an 8 year old American bulldog. The important radiographic findings are convexity of the right and cranial margins of the cardiac silhouette, convexity of the main pulmonary artery segment on VD view, and moderate to severe enlargement of pulmonary arteries with tortuosity and truncation. There are concurrent findings of a moderate to severe interstitial pulmonary pattern with areas of early alveolar coalescence and a mild to moderate bronchial pattern. The caudal vena cava is normal. The liver is incompletely included in the study limiting evaluation. A small cutaneous nodule is present on lateral view superimposed over the cardiac apex.
A large percentage of candidates failed to recognize the cardiac and main pulmonary artery changes likely due to the lack of overt heart size enlargement and abnormalities mainly related to cardiac shape. Similar numbers of candidates either did not evaluate pulmonary vessels or judged them to be normal. While the severity of the pulmonary infiltrates partially obscures the pulmonary vasculature, both pulmonary arteries and pulmonary veins remain adequately visible for evaluation. Most candidates correctly characterized pulmonary patterns. However, as these were the only abnormalities detected, a large number of candidates concluded that the dog had allergic lung disease. Some candidates added the diagnosis of a nodular interstitial pattern and additional candidates mistook enlarged pulmonary arteries at the heart base on lateral view for tracheobronchial lymphadenopathy and diagnosed mycotic pneumonia and, in some cases, diffuse pulmonary lymphoma and carcinoma. There are no findings on VD to support the diagnosis of tracheobronchial lymph node enlargement. A few candidates failed to recognize the characteristic findings of a cutaneous lesion visible on lateral view over the cardiac apex and diagnosed a pulmonary nodule, potentially mineralized.
The underlying factors contributing to the poor performance of large numbers of candidates on the radiographic diagnosis of a common clinical disease are uncertain. It may be speculated that the tendency of cardiologists in some practices to forego thoracic radiographs and evaluate patients solely with echocardiography may be limiting numbers of cardiac thoracic radiographs assessed by residents. Additionally, some radiology groups seem to take the position that cardiac disease can only be appropriately evaluated with echocardiography, and deemphasize interpretation of cardiac radiographs. The inappropriate evaluation of pulmonary vessels by some candidates was also apparent in additional cases on the examination.