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[Magnetic Resonance Imaging and Ultrasonography in Dogs and Cats with Ocular and Orbital Diseases. Part 1: Ocular Diseases]

Von Krosigk F., Steinmetz A., Ellenberger C., et al.

Tierarztl Prax Ausg K Kleintiere Heimtiere, 2012. 40(1): p.7-15.

Objective: This two-part study describes the clinical usefulness and value of ultrasound and magnetic resonance imaging (MRI) in dogs and cats with ocular (n=30) and orbital diseases (n=31). MRI and ultrasonography characteristics are described in single cases with ocular and orbital disease. Material and methods: Ultrasonography and MRI were performed in 15 dogs and 15 cats with intraocular neoplasia or intraocular inflammatory disease. Results: In all patients with intraocular neoplasia, sonography revealed masses with increased echogenicity and fairly uniform echotexture, thus allowing the tentative diagnosis of an intraocular tumour. In these cases, MRI often proved to be a valuable diagnostic tool in showing the complete extent of intraocular lesion. An additional benefit of MRI was seen in the tissue characterization of tumours based on MRI signal characteristics and pattern of contrast enhancement. Discreet intraocular inflammatory alterations, in particular to the anterior and posterior segment of the eyeball, were more clearly shown by ultrasound than by MRI. Neoplasia could be excluded and inflammatory disease was successfully diagnosed using MRI due to the different image sequences with or without contrast medium administration. Traumatic ruptures of the lens capsule and the globe after trauma were depicted more clearly with MRI. Conclusions and clinical relevance: When opacity of the anterior eye segment is present, various intraocular changes can be quickly diagnosed by ultrasound with high accuracy, without requiring anaesthesia of the patient. MRI of the globe allows differentiation of diverse pathologies, gives detailed information of infiltration in orbital structures and the exact degree of ocular lesions after trauma. This additional evidence often makes it easier to predict the correct prognosis and choose the best therapy.