Relationship between CT-Derived Bone Mineral Density and UTE-MR-Derived Porosity Index in Equine Third Metacarpal and Metatarsal Bones.
Authors: Daniel Carola Riccarda, Taylor Sarah Elizabeth, McPhee Samuel, Wolfram Uwe, Schwarz Tobias, Sommer Stefan, Kershaw Lucy E
Journal: Animals : an open access journal from MDPI
Summary
Fatigue-related injuries to the subchondral bone of the third metacarpal and metatarsal bones remain a significant welfare concern and leading cause of career-ending lameness in racehorses, yet our ability to assess bone strength non-invasively remains limited. Researchers used ultra-short echo time (UTE) MRI—a technique that captures signal from tightly bound water protons in compact bone—to calculate a porosity index (PI) in cadaver specimens, then validated this measure against quantitative CT-derived bone mineral density (BMD) to determine whether PI could serve as a practical indicator of bone quality. The two measures showed an inverse relationship, though correlation was weak (mean r = −0.29), with notably different correlations between forelimbs and hindlimbs, suggesting regional variation in how bone density and microarchitecture relate across the limbs. These findings indicate that whilst UTE-MRI has potential as a non-invasive imaging tool for evaluating bone health in the distal metacarpal and metatarsal regions, PI and BMD capture different aspects of bone quality and cannot yet be used interchangeably in clinical assessment. Further validation in living horses with documented stress injuries will be necessary before this technique can meaningfully inform risk stratification or training modifications in racing populations.
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Practical Takeaways
- •UTE-MRI offers a novel non-invasive imaging tool to assess bone quality and strength in racehorses at risk of career-ending injuries
- •The inverse relationship between bone density and porosity suggests opportunities to identify horses with compromised bone architecture before clinical lameness develops
- •Different correlation patterns between forelimbs and hindlimbs indicate that limb-specific risk assessment may be necessary for injury prevention strategies
Key Findings
- •BMD and PI are inversely correlated in equine distal McIII/MtIII bone with a weak mean r value of -0.29
- •Statistically significant differences exist in correlation patterns between forelimbs and hindlimbs
- •UTE-MRI sequences successfully detect signal in compact bone where traditional MRI methods fail
- •Porosity index is a promising indirect measure of bone strength in equine third metacarpal/metatarsal bones