CT Clues Help Spot Malignant Liver Tumors in Dogs

Computed Tomography Features for Differentiating Malignant and Benign Focal Liver Lesions in Dogs: A Meta-Analysis

S. Burti, A. Zotti, B. Contiero, T. Banzato

Background:
Focal liver lesions (FLL) are common incidental findings in dogs during imaging studies, but distinguishing malignant from benign lesions using computed tomography (CT) remains challenging. While human imaging guidelines are well-developed, there is no consensus in veterinary medicine on which CT features most reliably predict malignancy. This meta-analysis aimed to systematically identify qualitative and quantitative CT features that help differentiate malignant from benign FLLs in dogs.

Methods:
A systematic review and meta-analysis were performed following PRISMA guidelines. Studies evaluating CT features of FLL in dogs with histopathologic or cytologic confirmation were included. Pooled sensitivity, specificity, diagnostic odds ratio (DOR), and standardized mean differences (SMD) were calculated for qualitative and quantitative features, respectively. Both dual-phase and triple-phase CT protocols were considered. Risk of bias was assessed using the QUADAS-2 tool.

Results:
Eight studies encompassing 404 dogs and 419 FLLs were analyzed. Six qualitative CT features were deemed informative: well-defined margins, presence of a capsule, abnormal lymph nodes, and heterogeneity in arterial, portal, and delayed phases. Quantitative features associated with malignancy included larger maximum dimensions and ellipsoid volumes, and lower attenuation values of the lesion and surrounding liver tissue across different CT phases. Notably, heterogeneity in the portal phase showed the highest overall diagnostic accuracy (AUC 0.751). However, the diagnostic performance of individual features was only moderate, underscoring the need for pathological confirmation.

Limitations:
The study was limited by heterogeneity in CT protocols (dual- versus triple-phase), small sample sizes, retrospective designs, lack of blinding in pathology assessments, and inclusion bias in some studies. No power analyses were reported. The findings may not fully extrapolate to clinical populations outside academic settings.

Conclusions:
Specific CT features—particularly lesion heterogeneity, presence of a capsule, well-defined margins, and decreased attenuation—can aid in differentiating malignant from benign FLLs in dogs. However, imaging alone is insufficient for definitive diagnosis, and cytology or histopathology remains necessary. The findings support the development of future diagnostic algorithms and highlight the need for prospective studies.

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