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Magnetic Resonance Imaging

of the Stifle

Peter V. Scrivani

Introduction and image acquisition

Joints limit motion between bones to a partic-
ular range, and also dissipate stress during use
(Dyceet al. 2002). The ability to perform these
functions is based on the type of joint (synovial,
cartilaginous, fibrous), bone conformation, and
supporting soft tissues (Dyceet al. 2002). There-
fore, a loss of function is manifested as excessive
motion, restricted motion, or pain. In dogs the
most common cause of joint dysfunction is
osteoarthritis, a chronic degenerative disease of
the articular cartilage and underlying bone that
results from a combination of genetic and envi-
ronmental factors. Other common arthropathies
are due to inflammatory, traumatic, or neoplas-
tic causes. Relative to this information and to
the stifle joint in particular, the aims of magnetic
resonance imaging (MRI) are: (i) to provide an
early diagnosis of osteoarthritis; (ii) to provide
a more specific diagnosis of the arthropathy;
(iii) to guide therapy decisions; (iv) to offer a
more detailed prognosis; and (v) to assess any
response to treatment. MRI is apt to improve
patient care and help achieve one of these
goals.
The beneficial impact of musculoskeletal
MRI in humans is undisputed. However, only
minimal evidence is yet available in veterinary

medicine that MRI actually improves patient

care relative to the cost of the examination and

additional anesthesia time. Even though MRI is

considered accurate for diagnosing cruciate lig-

ament rupture (CR) in dogs (Galindo-Zamora

et al. 2013), competing diagnostic modali-

ties, such as radiography, ultrasonography, or

arthroscopy, offer additional benefits such as

guiding therapy without the need for anesthesia

or providing the ability to treat an underlying

problem during the same procedure. However,

MRI has shown much promise and may have

advantages in the early detection of lesions in

the cranial cruciate ligament (CrCL), subchon-

dral bone, articular cartilage or menisci, or for

establishing the cause of lameness that has not

been diagnosed by conventional methods. As

such, MRI is being used more frequently to

examine the stifle joint in dogs. The anatomy

of the stifle joint has been described previously

(Pujolet al. 2011).

MRI recognition of joint lesions is based

on alterations of signal intensity (SI) and

morphologic changes (Rubin 2005). For subtle

lesions, detecting these changes depends on

acquiring images with high contrast and spatial

resolution (Rubin 2005). It is difficult to make

exact recommendations for optimal image

acquisition because of different scanners (e.g.,

Advances in the Canine Cranial Cruciate Ligament, Second Edition. Edited by Peter Muir. © 2018 ACVS Foundation.
This Work is a co-publication between the American College of Veterinary Surgeons Foundation and Wiley-Blackwell.

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