46TH
ANNUAL
CONGRESS
OF
THE
SAEVA
SKUKUZA
16-‐20
FEBRUARY
2014
143
Imaging of the Sacroiliac Joint
Sarah M. Puchalski, DVM, DACVR
Pathology or pain arising from the sacroiliac region site is may cause lameness or
decreased performance and be problematic alone or in conjunction with pain or
lameness arising from other sites (thoracolumbar spine, hind or forelimbs) (Dyson
and Murray 2003). Localization of pain to this region is critically important via
clinical assessment, diagnostic anesthesia and imaging.
The sacroiliac region is difficult to image. The anatomic composition and the actual
anatomic location provide challenges for all modalities.
Radiography is infrequently performed. In order to obtain good quality, diagnostic
radiographs general anesthesia, a high output radiographic generator and a special
technique (motion induced blurring of abdominal viscera) are preferred (Gorgas,
Kircher et al. 2007). The x-ray beam passes through the joint at an oblique angle and
joint margins can be identified but additional or orthogonal projections cannot be
obtained. Variation in the size and shape of the sacroiliac joints and sacral wings, and
caudal sacral osteophytes are common; radiographs allowed for identification of the
inter-transverse joints (Gorgas, Kircher et al. 2007). These authors urged caution in
the interpretation of lesions identified on radiograph in absence of other diagnostic
imaging and clinical examination.
Ultrasound examination is common. Ultrasound cannot penetrate the central
portion of the joints does evaluate the periphery and the regional, soft tissues
implicated in pain arising from this region. Techniques for transcutaneous and perrectal ultrasound examination have been described (Kersten and Edinger 2004;
Engeli, Yeager et al. 2006). As with the radiographic anatomy of the region,
variability exists in the appearance of the tubera sacrale, dorsal sacroiliac ligaments
and thoracolumbar fasciae (Engeli, Yeager et al. 2006). Artifacts of acquisition and
interpretation can occur in ultrasound evaluation of this region and care should be
taken to obviate these artifacts. Ultrasound should also be interpreted in light of the
clinical signs and other diagnostic techniques.
Nuclear scintigraphy is a very important component of work-up for sacroiliac region
pain. Several reports exist detailing the anatomy and technique (Erichsen, Berger et
al. 2002; Erichsen, Eksell et al. 2003), findings in normal horses (Dyson, Murray et al.
2003; Erichsen, Eksell et al. 2003) and findings in lame horses (Dyson, Murray et al.
2003). Nuclear scintigraphy is prone to artifacts. Patient motion and camera
positioning can cause artifacts at acquisition. Gluteal muscle asymmetry can cause
the appearance of asymmetry in uptake confounding interpretation. Motion
corrected images (Dyson, Murray et al. 2003) and region of interest analysis (Gorgas,
Luder et al. 2009) are recommended by some authors. In normal horses, the
appearance of the sacroiliac region varies with age but is generally symmetric
(Dyson, Murray et al. 2003). In horses with sacroiliac problems, it more difficult to
distinguish the tubera sacrale from the sacroiliac joint than in normal horses and in
horses with lameness, there is more asymmetry detected (Dyson, Murray et al.
2003).
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