CT and MRI Features of Aortic Body Paragangliomas in 44 Dogs.

Aortic body paragangliomas (ABPs) are the most common heart base tumor in dogs; however, descriptions of their computed tomography (CT) and magnetic resonance imaging (MRI) findings are lacking. Although generally considered benign, ABPs can present as malignant neoplasms with local invasion and metastasis. The objectives of this study were to describe the CT and MRI features of confirmed benign and malignant ABPs and identify significant features associated with malignancy. Forty-four dogs with 43 CTs and 3 MRIs were included. Most (68%) dogs were males, and 48% were brachycephalic breeds. At CT, ABPs were mostly heterogeneously contrast-enhancing, well-marginated, lobular or ovoid, and frequently fluid-cavitated. At MRI, ABPs had heterogeneous T2 hyperintensity, uniform contrast enhancement, a variable "salt-and-pepper" sign, and fluid-cavitated regions. Local invasion was noted in 11 cases. Thirteen dogs had confirmed metastatic lesions, with the most common sites being local lymph nodes, heart, and bones. ABPs frequently displaced and compressed regional structures and less often encircled vasculature. Pericardial and peritoneal effusions were significantly associated with confirmed metastasis. Encircling of vessels, mediastinal effusion, and right-sided congestive heart failure were significantly associated with invasion. ABPs may be present in non-brachycephalic breeds, and malignant masses have the potential for regional invasion and distant bone metastasis.