Magnetic resonance imaging following regional limb perfusion of gadolinium contrast medium in 26 horses.

Abstract

Systemic administration of gadolinium contrast medium is common in small animals to increase lesion conspicuity and determine vascularisation of lesions identified with magnetic resonance imaging (MRI); however, the large volume required for systemic administration limits its use in horses. The purpose of this study was to assess the feasibility of administering a low dose of contrast medium via venous regional limb perfusion. Prospective clinical study. Distal limbs of 26 horses (one limb per horse) were imaged with MRI before and after administration of 5 mL of gadopentetate dimeglumine (Magnevist® ) diluted with 5 mL of physiological saline via a palmar/plantar digital vein with a tourniquet in place at the level of the mid aspect of the third metacarpal/metatarsal bone. Commonly assessed structures of the equine distal limb were examined for normal and abnormal contrast enhancement. Twenty-five of 26 horses had adequate contrast enhancement of their distal limb. The lack of adequate contrast enhancement in one limb was likely associated with failure of the tourniquet. No adverse reactions were identified in any horse. One hundred thirty-two lesions were detected, of which, 69 contrast enhanced. Twelve lesions were detected exclusively following contrast enhancement. Case numbers and lesion variability yielded insufficient data to perform statistical analyses. Histopathology was not performed on sound horses to determine if the imaged structures were normal. Regional limb perfusion is a feasible method to administer gadolinium contrast material to the equine distal limb for MRI. The enhancement pattern of the equine distal limb in sound horses is described. Contrast enhanced MRI of the distal equine limb helps to further characterise lesions identified with precontrast images, including adhesions and deep digital flexor tendinopathy. Contrast enhanced MRI also aids in identification of additional lesions, such as neovascularisation.