138
46TH
ANNUAL
CONGRESS
OF
THE
SAEVA
SKUKUZA
16-‐20
FEBRUARY
2014
T1, requires higher output parameters, limiting this region to radiography by more
powerful fixed x-ray generators (ex. kVp 130 and mAs 30). The use of 27.9 x 43.2
cm cassettes or digital panel of similar size is encouraged to aid in interpretation as 3
vertebral units are projected on each cassette thereby allowing for comparison
between vertebrae. Smaller cassettes or detectors are adequate but require greater
accuracy in acquisition. In all cases, external radio-opaque markers taped to the skin
surface at each vertebra are strongly recommended. This allows the clinician to
differentiate one vertebra from the next on the radiographs.
The designated radiation safety officer, often the supervising veterinarian, is
responsible for radiation safety and employee education. Radiation safety
recommendations to keep exposure as low as reasonably achievable (ALARA) are
frequently overlooked in equine practice. Cervical spine studies require high tube
output and safety rules should be observed. Cassette holders and lead gloves in
addition to lead aprons should be used for these studies. Personnel with high
occupational exposure should consider cornea and thyroid protection when distance
and shielding cannot be used to decrease exposure. Personnel should never be in the
path of the primary beam, on either side of the detector. All persons with
occupational exposure should wear dosimeters.
A systematic and thorough approach to the interpretation of cervical radiographs or
any other imaging modality should be undertaken. Each vertebra and its processes
should be evaluated for alteration in size, shape, opacity and margination. The
intervertebral joints including the disc space and the facet joints should be evaluated
for alignment and peri-articular remodelling. Radiographic signs of osteoarthritis
include osteophytes, peri-articular new bone proliferation, abnormal joint space and
subchondral bone sclerosis. The facet joints are no different except that the anatomy
is more confusing (Levine et al. 2007; Down and Henson 2009). The laminae and the
spinal canal diameter should also be assessed. More detailed descriptions of the
evaluation of lateral-lateral radiographs including qualitative and quantitative
measures for spinal cord compression prediction has been described (van Biervliet et
al. 2004; Hudson and Mayhew 2005; Hahn et al. 2008). Oblique radiographs should
be taken to better characterise abnormalities seen on the lateral radiographs or to
image regions identified as abnormal on clinical examination (stiffness in a specific
direction or pain on palpation). Ultrasound evaluation of the cervical spine is critical
and provides complementary information in the assessment of facet or transverse
process pathology (Berg et al. 2003; Nielsen et al. 2003; Mattoon et al. 2004).
Fig 1: Lateral-lateral radiograph (A), labelled radiograph (B) and anatomical specimen (C) of cervical
vertebrae 1-3 (C1, C2, C3). a = dens of C2, b = spinous process, c = caudal articular process of C2, d
= cranial articular process of C3, e = transverse process of C3, f = intervertebral disk space, g =
vertebral canal.
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