Time-of-flight magnetic resonance angiography (TOF-MRA) of the normal equine head.

This research paper presents a study to visualize and understand the vascular network of a horse’s head using noncontrast Magnetic Resonance Angiography (MRA), a potentially safer and more cost-effective method than earlier techniques. The study was successful in visualizing major intra- and extracranial vessels in horses using both low- and high-field MRI systems without needing contrast media for MRA.

Methodology and Procedure

• The study focused on five healthy adult horses. Four of the subjects were tested using a low-field magnet, set at 0.23T, while the remaining one was evaluated using a higher-field magnet, set at 1.5T.
• A specific sequence used for the MRA, the TOF (time-of-flight) 2D-MRA, was employed for the evaluation process. CT images from a vascular corrosion cast were then used as anatomical references for comparative study.

Results and Findings

• The MRA imaging protocol showed that it was highly capable of visualizing all major intra- and extracranial vessels down to approximately 2mm in diameter. Both low- and high-field MRI systems were able to achieve this accuracy, identifying vessels up to 3rd-4th ramification branching levels.
• The visibility of arteries was found to surpass the level of visibility of veins due to a higher signal intensity. The study also found out that MRA imaging was far superior when the high-field protocol was used, due to its ability to visualize all the small arterial branches with better resolution.

Conclusion and Implications

• The study confirmed that employing a dedicated vascular sequence such as TOF 2D-MRA can provide excellent visualization of the equine head vasculature without the need for contrast media for Magnetic Resonance Angiography. This spells many benefits, foregrounding the superior cost-effectiveness and safety of this technique.
• The procedure provides an excellent understanding of vessel morphology, symmetry, and size. This could be invaluable in preoperative planning or in diagnosing and treating diseases like neoplasia or guttural pouch mycosis.