Intra-arterial contrast enhanced computed tomography of the deep digital flexor tendon and palmar veins in the distal forelimb in Jeju horses: Evaluating contrast-enhancing factors.
Authors: Lee Seyoung, Shin Kwang-Yun, Lee Kija, Seo Jong-Pil
Journal: Equine veterinary journal
Summary
# Editorial Summary Contrast-enhanced CT has become increasingly valuable for evaluating soft tissue injuries in equine distal limbs, yet optimal imaging protocols remain poorly defined. Lee and colleagues conducted 54 intra-arterial CT scans across six horses to determine how different scanner settings and contrast media (CM) parameters affect visualisation of the deep digital flexor tendon (DDFT) and palmar veins. They found that DDFT enhancement was significantly superior at lower scanner voltage (80 kV) combined with higher CM concentration (150 mg iodine/mL), with contrast enhancement showing a strong positive correlation to CM concentration (r = 0.75), whilst adequate venous visualisation could be achieved at substantially lower iodine delivery rates (180 mg iodine/second rather than 300) when using higher injection volumes and rates. For equine practitioners performing contrast-enhanced CT of the distal forelimb, these findings suggest that diagnostic image quality need not depend on high-concentration contrast agents; instead, optimising scanner parameters and injection protocols can maintain diagnostic visibility of both soft tissues and vascular structures whilst potentially reducing contrast load and associated costs—a practically significant finding given the expense and rare but possible adverse reactions to iodinated contrast media in horses.
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Practical Takeaways
- •When ordering intra-arterial CECT for distal forelimb soft tissue evaluation, specify lower contrast concentration (30–90 mg I/mL) as it may reduce contrast load while maintaining diagnostic quality
- •Protocol optimization (voltage, volume, rate) allows clinicians to achieve adequate DDFT and vascular visualization with reduced contrast media burden on the patient
- •For palmar vein assessment, higher injection rates (6 mL/s) and larger volumes (150 mL) provide clearer vessel differentiation from surrounding structures
Key Findings
- •Contrast enhancement of DDFT was significantly higher at 80 kV voltage and 150 mg I/mL concentration (Median: 29.65; IQR: 1.74; p < 0.05)
- •DDFT contrast enhancement positively correlated with contrast media concentration (p < 0.001; r = 0.75)
- •At 180 mg I/s iodine delivery rate, palmar vein contrast attenuation was optimal with 30 mg I/mL concentration, 6 mL/s injection rate, and 150 mL volume (985.93–988.73 HU)
- •Lower contrast media concentration can yield sufficient imaging of DDFT and arteries when CT scanning parameters and injection parameters are optimized