Ultrasonography and Sonoelastography Characteristics of Benign vs. Malignant Mesenteric Lymph Nodes in Cats: An Update

SIMPLE SUMMARY: This study aimed to evaluate the feasibility of using a multivariate diagnostic approach by combining B-mode ultrasound, color Doppler ultrasonography, and strain elastography (SE) to distinguish benign from malignant mesenteric lymph nodes in cats. Feline enlarged mesenteric lymph nodes (LNs) were evaluated using B-mode ultrasound, color Doppler ultrasonography, and SE. Short-to-long axis ratio, borders, echogenicity, hilum, vascular flow distribution, elastographic pattern, and strain ratio were recorded. Histological and/or cytological diagnosis was available for each LN. A multivariate statistical analysis was performed including the data from B-mode ultrasound, color Doppler ultrasonography, and SE. A total of 88 LNs were included, 46 (52.3%) benign and 42 (47.7%) malignant; in the benign group, 40 LNs had a diagnosis of reactive hyperplasia (group A) and 6 eosinophilic sclerosing lymphadenitis (group B), while in the malignant group 42 had a diagnosis of lymphoma (group C). The principal component analysis approach provided evidence that by combining B-mode-based scores, the three groups of LNs can be accurately distinguished. Combining B-mode- and color Doppler-based scores with SE scores allows reactive lymph nodes to be distinguished from other lymph node abnormalities. Further studies are needed for neoplastic and inflammatory conditions in feline species. ABSTRACT: (1) Background: Strain elastography (SE) is an ultrasound-based technique able to non-invasively assess tissue elasticity, with malignant tissues being stiffer than normal tissues. The purpose of the study was to evaluate the diagnostic performance of SE to differentiate feline mesenteric benign and malignant lymph nodes (LNs) using a multivariate approach including both SE results and B-mode ultrasound and color Doppler findings. (2) Methods: Feline enlarged mesenteric LNs were evaluated using B-mode ultrasound, color Doppler ultrasonography, and SE. Short-to-long axis ratios, borders, echogenicity, hilum, vascular flow distribution, elastographic patterns, and strain ratios were recorded. Histological and/or cytological diagnosis was available for each LN. (3) Results: A total of 88 LNs were included, 46 (52.3%) benign and 42 (47.7%) malignant; in the benign group, 40 LNs had a diagnosis of reactive hyperplasia (group A) and 6 eosinophilic sclerosing lymphadenitis (group B), while in the malignant group 42 had a diagnosis of lymphoma (group C). The principal component analysis approach showed evidence that by combining B-mode- and color Doppler-based scores with SE scores, the three groups of LNs can be accurately distinguished. (4) Conclusions: Our results demonstrate that a multivariate sonographic approach combining B-mode ultrasound, color Doppler ultrasonography, and SE can accurately distinguish benign from malignant LNs, thus helping in the clinical advice of feline patients.