Magnetic Resonance Imaging of Focal Splenic and Hepatic Lesions in the Dog

Abstract

Focal hepatic and splenic lesions in the dog are common, and approximately half of such lesions are malignant. Both incidentally discovered lesions and lesions in patients with known malignancies represent diagnostic dilemmas. Ultrasound often fails to characterize such lesions adequately. This uncertainty may result in unnecessary splenectomies and liver biopsies for benign lesions or noncurative surgery for advanced-stage malignancies. In humans, ultrasound largely has been supplanted by computed tomography and magnetic resonance imaging (MRI) for the characterization of focal hepatic and splenic lesions. The inherently high soft tissue contrast of MRI allows the differentiation of benign from malignant hepatic and splenic lesions in the human patients. In this prospective study, 35 focal lesions of either the spleen (n ϭ 8) or the liver (n ϭ 27) were characterized by MRI in 23 dogs. Lesions were presumptively classified as malignant or benign on the basis of MRI findings. Imaging results then were correlated with histopathologic (29) or cytologic (6) evaluation of the lesions. The overall accuracy in differentiating malignant from benign lesions was 94% (33 of 35 lesions). The overall sensitivity and specificity were 100% (95% CI, 78-100%) and 90% (95% CI, 68-99%), respectively. MRI classified malignant hepatic lesions as hepatocellular carcinoma (HCC) in all confirmed cases and correctly predicted the histologic grade of 5 HCC lesions. These results suggest that MRI is a useful modality for abdominal imaging in veterinary patients, and MRI accurately differentiated benign from malignant focal hepatic and splenic lesions in this sample of patients.Key words: Abdominal imaging; Hemangiosarcoma; Hepatocellular carcinoma; Nodular hyperplasia.I n the canine liver, focal lesions may represent benign (eg, focal nodular hyperplasia [FNH] or regeneration, extramedullary hematopoiesis, cyst, abscess, hematoma) or malignant (eg, hepatocellular carcinoma [HCC], lymphosarcoma, malignant histiocytosis, hemangiosarcoma, metastatic carcinoma, metastatic sarcoma) processes. [1][2][3][4] Similarly, focal lesions in the spleen may be the result of benign (eg, lymphoid hyperplasia, cyst, abscess) or malignant (eg, hemangiosarcoma, metastatic sarcoma/carcinoma, malignant histiocytosis, lymphosarcoma) conditions. 5-8 These lesions traditionally have been identified by radiography or ultrasonography and commonly represent a diagnostic dilemma for the clinician, because each may require substantially different management. 1,2 Ultrasound is commonly used for abdominal imaging in veterinary medicine, but its ability to distinguish benign from malignant lesions in the liver and spleen is poor. 9-12 Consequently, unnecessary surgeries or biopsies may be performed on patients with benign lesions.In humans, the limitations of ultrasound are well recognized, and its role in specific patients is limited. Magnetic resonance imaging (MRI) provides soft tissue contrast that is far superior to that provided by either ultrasound or computed to...

Estudo retrospectivo de lesões em baços de cães esplenectomizados: 179 casos

“…Todavia o diagnóstico definitivo é obtido somente através da análise histológica da lesão (Rodaski & Piekarz 2009). A imagem obtida por ressonância magnética teve 100% de sensibilidade e especificidade na diferenciação de lesões esplênicas focais benignas e malignas em oito cães analisados (Clifford et al 2004).…”

A comparison of microRNA expression profiles from splenic hemangiosarcoma, splenic nodular hyperplasia, and normal spleens of dogs

“…However, these values can only be calculated after splenectomy, and splenic size can change due to contraction or engorgement in response to medications or hemoperitoneum. Diagnostic imaging has been evaluated for its ability to differentiate malignant from benign lesions with contrast harmonic ultrasound, CT, and MRI showing promise [9–11]. Such modalities may differentiate malignant from benign lesions but do not diagnose a specific disease process.…”

Imaging in Oncology

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