title: Time-of-flight magnetic resonance angiography (TOF-MRA) of the normal equine head.
abstract: BACKGROUND
  Noncontrast magnetic resonance angiography (MRA) is widely used in human and small animal medicine. However, this technique has not yet been described in the horse, and compared to other angiographic techniques MRA could be more cost efficient and potentially safer.
  
  
  OBJECTIVE
  The aim of this study was to provide a comprehensive anatomical reference of the normal equine head vasculature using a noncontrast MRA technique, on both low- and high-field MRI.
  
  
  METHODS
  Five healthy adult horses were examined, 4 with a low-field magnet (0.23T) and the remaining one with a high-field magnet (1.5T). The magnetic resonance angiography sequence used was TOF (time-of-flight) 2D-MRA and CT images of a vascular corrosion cast were subsequently used as anatomical references.
  
  
  RESULTS
  The MRA imaging protocol provided good visualisation of all major intra- and extracranial vessels down to a size of approximately 2 mm in diameter on both low- and high-field systems. This resulted in identification of vessels to the order of 3rd-4th branches of ramification. The visibility of the arteries was higher than of the veins, which showed lower signal intensity. Overall, MRA obtained with the high-field protocol provided better visualisation of the arteries, showing all the small arterial branches with a superior resolution.
  
  
  CONCLUSIONS
  The use of a specific vascular sequence such as TOF 2D-MRA allows good visualisation of the equine head vasculature and eliminates the need for contrast media for MRA.
  
  
  CONCLUSIONS
  Magnetic resonance angiography allows for visualisation of the vasculature of the equine head. Vessel morphology, symmetry and size can be evaluated and this may possibly play a role in preoperative planning or characterisation of diseases of the head, such as neoplasia or guttural pouch mycosis.
authors.affiliation: Department of Animal Medicine and Surgery, School of Veterinary Medicine, Universidad Complutense de Madrid, Spain. gmanso@vet.ucm.es
authors.forename: G
authors.initials: G
authors.lastname: Manso-Díaz
authors.forename: M I
authors.initials: MI
authors.lastname: García-Real
authors.forename: C
authors.initials: C
authors.lastname: Casteleyn
authors.forename: F
authors.initials: F
authors.lastname: San-Román
authors.forename: O
authors.initials: O
authors.lastname: Taeymans
mesh_terms: D000818:Animals; D006257:Head / Q000098:blood supply*; D006736:Horses / Q000033:anatomy & histology*; D018810:Magnetic Resonance Angiography / Q000379:methods / Q000662:veterinary*