The sacroiliac joints: evaluation using nuclear scintigraphy. Part 1: The normal horse.
Authors: Dyson S, Murray R, Branch M, Whitton C, Donovan T, Harding E
Journal: Equine veterinary journal
Summary
# Editorial Summary: Nuclear Scintigraphy of Normal Equine Sacroiliac Joints Sacroiliac disease remains a challenging diagnosis in equine practice, yet the imaging reference standards for these joints have been poorly defined. Dyson and colleagues used dorsal nuclear scintigraphy on 40 clinically normal horses (aged 3–16 years) to establish baseline patterns of radiopharmaceutical uptake, overlaying images onto isolated pelvic radiographs to confirm anatomical landmarks and determine how age and symmetry affect normal appearance. The tubera sacrale demonstrated clearly defined uptake that decreased significantly with advancing age, whilst the sacroiliac joint regions themselves showed consistent uptake independent of age or sex; critically, motion-corrected imaging proved essential for diagnostic accuracy, as noncorrected images frequently mimicked pathology. Because normal horses exhibited marked bilateral symmetry in both tuber sacrale and sacroiliac joint regions, substantial left-right asymmetry should be considered abnormal and warrants further investigation. These baseline data provide equine vets with essential reference parameters for interpreting scintigraphic images of horses with suspected sacroiliac dysfunction, enabling more confident differentiation between normal age-related changes and genuine pathology affecting hindlimb performance.
Read the full abstract on PubMed
Practical Takeaways
- •When evaluating suspected sacroiliac disease with scintigraphy, always compare against normal horses of similar age—uptake patterns change significantly with age, particularly in the tubera sacrale
- •Marked asymmetry between left and right sacroiliac regions is likely abnormal; use symmetry as your main diagnostic criterion in normal horses
- •Ensure your scintigraphic images are motion-corrected before interpretation—non-corrected images frequently lead to misdiagnosis and should not be used clinically
Key Findings
- •Tubera sacrale show significantly higher radiopharmaceutical uptake than sacroiliac joints and L5 in normal horses
- •Radiopharmaceutical uptake in tubera sacrale decreases with age while SI joint uptake remains stable
- •Normal horses demonstrate high degree of left-right symmetry in both tubera sacrale and SI joint regions (>95% symmetrical)
- •Motion-corrected scintigraphic images are essential for accurate diagnosis as non-corrected images are often non-diagnostic or misinterpreted as abnormal