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Ultrasonography (US) and computed tomography (CT) are used to diagnose neoplastic and non‐neoplastic focal renal lesions in dogs and cats; however, comparative studies between these two diagnostic tools are lacking. The aim of this retrospective, methods comparison study was to evaluate and compare the performance of US compared to CT in identifying at least one renal nodule in animals with confirmed focal renal lesions. Imaging studies of animals with uni‐ or bilateral renal nodules smaller than 3 cm that underwent both US and CT and that had a pathologically confirmed diagnosis were reviewed. Animals with renal cysts and infarcts were excluded. Recorded features for both modalities included the following: shape, size, number, localization, margins, renal profile. For CT only, recorded features also included attenuation (HU) and pattern of enhancement. For US only, recorded features also included echogenicity, echostructure, and rate of visibility. Final diagnosis was obtained by cytology or histopathology. Using CT, lesions were identified in all 39 (100%) kidneys of 18 dogs and seven cats. Most lesions were multiple, cortical, well‐defined, iso‐attenuating (precontrast), hypo‐attenuating, and moderately enhancing (postcontrast). Using US, lesions were identified in 29 of 39 (74%) kidneys. Overall, nine (31%) lesions were poorly visible; 10 (26%) kidneys appeared normal; in 17 (59%) organs, lesions' number was underestimated. Isoechoic, non‐protruding lesions were difficult to identify by US. Ultrasonography underestimated renal lesions compared to CT in 59% of the kidneys (P = 0.001). Final diagnoses included metastatic disease (n = 16), infiltration by feline lymphoma (n = 4), primary neoplasia (n = 3), and non‐neoplastic benign lesions (n = 2). [ABSTRACT FROM AUTHOR]

OBJECTIVE: The aim of this study was to evaluate the CT features of pulmonary metastases in dogs with hemangiosarcoma (HSA) at various sites. Additionally, the CT characteristics of extrapulmonary metastases in the same population were assessed. METHODS: Retrospective, observational, and descriptive study conducted from April 2013 to January 2024. Dogs with histologically confirmed HSA and suspected or cytologically/histologically confirmed lung metastases were included. Dogs were excluded if they had a second primary tumor or only 1 unsampled pulmonary nodule. RESULTS: 33 dogs were included, with 26/33 [78.8%] having more than 10 metastatic pulmonary nodules. Most nodules were generalized (24/33 [72.7%]), miliary (29/33 [87.9%]) to subcentimetric (32/33 [97%]) in size, well-defined margins (29/33 [87.9%]), or a perilesional halo sign (24/33 [72.7%]). When more than 10 nodules were present, a generalized distribution was prevalent, while a peripheral location was more common when 2 to 10 nodules were present (P < .0001). In 32/33 (97%) cases, a pulmonary vessel was directly connected to the nodule (feeding vessel). After contrast administration, most lung metastases appeared homogenous (26/33 [78.8%]), although some showed areas of intense enhancement (5/33 [15.1%]) a feature also observed in extrapulmonary metastases with varying frequency (0% to 85.7%). CONCLUSIONS: Pulmonary HSA metastases were characterized by generalized, small (miliary/subcentimetric), well-defined nodules, commonly associated with a halo sign and feeding vessel. Intralesional areas of spotty postcontrast linear or amorphous strong hyperdensity were frequently observed especially in extrapulmonary metastases. CLINICAL RELEVANCE: These features may help radiologists and clinicians orient their diagnosis toward metastatic HSA. [ABSTRACT FROM AUTHOR]