Multi-Detector Helical Computer Tomography, Transrectal Ultrasonography and Histology of the Lumbosacral Area: A Comparative Study in Warmblood Horse Cadavers.

Overview

• This study compared the effectiveness of multi-detector helical computed tomography (CT) and transrectal ultrasonography (US) in evaluating lumbosacral joint and disc structures in Warmblood horse cadavers by correlating imaging findings with histological results.
• The goal was to better understand the imaging changes in these structures and how they relate to actual tissue pathology, especially since some abnormalities may occur even in horses without clinical symptoms.

Background

• The lumbosacral region in horses is a common source of pain that can reduce performance and welfare.
• Key anatomical features prone to changes include the intertransverse joints (ITJs), lumbar articular process joints (APJs), and lumbosacral intervertebral discs (LSDs).
• However, these structures can show structural changes even in horses without lameness or pain, complicating the interpretation of imaging results.

Study Subjects and Methodology

• The research was conducted on 14 Warmblood horse cadavers that were not lame before euthanasia or slaughter.
• Initially, transrectal ultrasonography (US) was used to image the ITJs and LSDs due to their accessibility via this technique.
• Next, multi-detector helical computed tomography (CT) scans were performed on the same regions for detailed cross-sectional imaging.
• Histological examination was performed on a subset of the specimens:
  • 13 ITJ samples
  • 5 APJ samples
  • 5 LSD samples
• Correlation analyses were conducted using Spearman’s rank correlation to explore relationships between imaging scores (US and CT) and histological findings.

Key Findings

• Mild abnormalities were common across all evaluated structures, regardless of clinical symptoms before death.
• Intertransverse Joints (ITJs):
  • CT scores significantly correlated with histological scores (Spearman’s ρ = 0.679, p = 0.011), indicating CT could reflect underlying tissue changes here.
  • Ultrasonographic findings did not show significant correlation with histology for ITJs.
• Lumbar Articular Process Joints (APJs):
  • Mild changes were noted on CT but these did not correlate significantly with histological abnormalities, suggesting imaging changes might not indicate active disease.
• Lumbosacral Intervertebral Discs (LSDs):
  • Subtle imaging changes were documented.
  • Significant correlation was observed between US and CT findings (Spearman’s ρ = 0.748, p < 0.01), meaning US and CT generally agreed on these subtle changes.
  • Neither imaging method showed significant correlation with histopathology for discs, suggesting imaging abnormalities may reflect adaptive or other non-pathologic changes.

Interpretation of Results

• Mild imaging abnormalities appear frequently in the lumbosacral region of horses without clear clinical signs.
• CT is more sensitive in detecting histologically relevant changes in ITJs than US, which may be less reliable for these joints.
• Imaging findings in APJs and LSDs should be interpreted with caution, as mild changes may represent adaptive remodeling rather than clinically significant disease.
• These results highlight the complexity of diagnosing clinically relevant lumbosacral disease based solely on imaging, given that structural alterations may exist without causing symptoms.

Conclusions and Clinical Significance

• Veterinarians should be cautious in over-interpreting mild abnormalities seen on CT or US scans of the lumbosacral area, especially in horses with no clinical signs.
• CT imaging is useful for detecting certain joint changes consistent with histopathology, particularly in ITJs.
• Transrectal ultrasonography correlates well with CT for disc changes but may not reflect histologic pathology.
• Further studies might be needed to distinguish which imaging findings truly correspond to pathological conditions warranting treatment versus incidental or adaptive changes.