4
46TH
ANNUAL
CONGRESS
OF
THE
SAEVA
SKUKUZA
16-‐20
FEBRUARY
2014
Radiography and Multi-modality
imaging of the Foot
Sarah M. Puchalski, DVM, DACVR, [email protected]
Diagnostic imaging of the equine foot
Diagnostic imaging techniques such as transcuneal ultrasound1, nuclear scintigraphy2,3,
MRI 4-9, and CT10-12 have demonstrated a range of osseous and soft tissue injury
within the foot that has been previously poorly understood. It is arguable that the
utilisation of these novel diagnostic-imaging techniques has led to a resurgence of
clinical studies interested in the characterisation of ‘navicular syndrome’. The result
of this interest is a much greater understanding of foot pathology.
Pathology of the podotrochlear apparatus and deep digital flexor tendon, distal
interphalangeal joint and associated ligaments7, and the ungual (collateral) cartilages
and distal phalanx6,13,14 have all been associated with lameness in horses and can be
diagnosed with a variety of different imaging modalities. The problem remains,
however, of which diagnostic imaging technique to choose. In order to utilise
diagnostic imaging modalities to their fullest capability, the diagnostician must
understand both the limitations of the test and the expected pathology. The
frequency of expected pathology is reported with some variability depending on the
publishing group and hospital populations but many similarities exist 7,15. Beyond the
idealistic situation where monetary limitations are non-existent and multiple imaging
modalities are available, the more common scenario involves budgetary restrictions
and limited access to certain types of imaging. The improved understanding of foot
and distal pastern pathology augments the value of more routine diagnostic imaging
techniques such as radiography and pastern / foot ultrasound.
Diagnostic Imaging - Radiology
Advancing computer technology promotes the evolution of all digital diagnosticimaging modalities, and radiography is no exception. Digital radiography technology
allows for more diagnostic images of more anatomic regions. The advantages of
digital imaging are largely provided by the linear response of digital detectors to
radiation dose and digital image processing16. These advantages are identified clearly
when imaging through complicated regions such as the central portion of the foot or
tarsus. Furthermore, reviewing software further improves the utility of digital
radiographs17. So although digital radiography has lower spatial resolution then
traditional film screen systems, its other positive qualities are generally considered to
be of greater importance.
Radiography of the foot is still considered a mainstay of its diagnostic work-up. A
high quality radiographic examination with an adequate number of projections
provides an overview of the region that can solve many clinical questions regarding
foot lameness. The obvious shortcomings of radiography include the problem of
superimposition and the inability to define and detect injury of the soft tissues.
Further, radiography does not provide physiological information regarding the
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