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EQUINE VETERINARY EDUCATION / AE / FEBRUARY 2022
a)
b)
Fig 4: Multi-planar reformatted frontal (a) and sagittal (b) reconstructed CT images (bone window) of the right tarsus of a 6-year-old stallion. There is a circumscribed hypoattenuating zone on the cranial aspect of the distal intermediate ridge of the tibia (arrow). The image shows mild motion artefact. Note the flexed position of the tarsocrural joint due to the limb positioning. Right is lateral and caudal.
C G B
H A F
D E
Fig 5: Multi-slice helical CT gantry (A) built over a platform (not seen on the image). The CT gantry is positioned for imaging metacarpophalangeal region. There are extensions attached to the platform to support the head during the scanning, reducing the motion artefact. B) (metal stand) and (C) (rope) provide head support during the scan. D is U-form wood board attached to the CT table to facilitate foot positioning. E is a safety wood wall to prevent dropping the horse limb in the gap created when the gantry slides away from the horse during the scan. Furthermore, it provides additional support to the CT table during loading of the horse limb. F is a side column attached to the platform for fixing a rope to prevent the horse leaning against the gantry. G is the lead window of the CT operating room to monitor the horse during the scan. H is a mobile lead shielded cabin. The gantry can be moved down in a pit in the ground to position the anatomical region of interest at the isocentre of the gantry.
Patient preparation and positioning A clinical examination of the horse is always conducted prior to imaging. The shoe of the examined limb is removed if the foot is the anatomical region of interest. An intravenous injection of detomidine (10 lg/kg bwt; Domosedan 10 mg/ mL)2 and butorphanol tartrate (0.1 mg/kg bwt; Torbugesic Vet 10 mg/mL)3 was administered prior to bringing the horse
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into the CT room. Every horse should be carefully positioned with the feet as close to the platform as possible. For imaging distal anatomical regions, such as the foot and metacarpophalangeal region, the horse is positioned at 90° to the platform in order to position the limb at the isocentre of the gantry. This is done in extension to avoid compression of the joint space in one side. In this case, the head is
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