46TH
ANNUAL
CONGRESS
OF
THE
SAEVA
SKUKUZA
16-‐20
FEBRUARY
2014
7
diagnostic imaging, most advantages come with a cost seen at a different level. For
example, gradient recalled echo (GRE) sequences are faster and allow for thin slices
of tissue thereby improving out of plane resolution (mitigating volume averaging
artifact) but are more sensitive to susceptibility artifact, which causes anatomic
distortion in the image (generated by paramagnetic or ferromagnetic substances such
as iron filings).
Debate over the merits of high (>1.0Tesla) versus low field (<1.0Tesla) strength MRI
abounds. New work emerges, trying to settle this debate on a scientific basis32-34. It
remains useful to consider the advantages and disadvantages of high and low field
MRI with regards to image quality in addition to clinical and logistical aspects of the
imaging modality. High field MRI provides better image quality through the
generation of higher signal to noise ratios with smaller pixel pitch and overall better
spatial and contrast resolution. Software, hardware and programming advances are
more common and numerous in high field MRI as the human medical imaging market
drives development. Low field MRI is more cost effective, has useful image qua lity
and can be modified for use in the standing, sedated horse. The overwhelming merit
of standing low-field MRI is that it obviates the need for general anesthesia and its
associated risks. The downside is that even marginally perceptible patient motion, as
expected in the standing sedated horse, can cause some degree of image quality
degradation. While the desire to produce the best quality study possible is
understandable, veterinarians must ask themselves, ‘what is an acceptable trade-off
for clinically relevant information?’
Summary
The accurate diagnosis of foot lameness is critical to the procurement of an accurate
prognosis and the development of a sensible management strategy for the individual
horse. Many, if not all diagnostic imaging modalities can provide meaningful
information in this regard. Each modality should be considered with its strengths
and weaknesses in every diagnostic work-up in order that the best test is chosen and
the results are interpreted correctly. Furthermore, the combination of diagnostic
imaging modalities advances our understanding of foot related lameness.
References
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