title: Intra-arterial versus intra venous contrast-enhanced computed tomography of the equine head.
abstract: BACKGROUND
  The anatomical complexity of the horse's head limits the abilities of radiography. Computed tomography (CT) in combination with contrast enhanced CT is used more often for diagnosing various head pathology in horses. The objective of this study was to compare intravenous and intra-arterial contrast-enhancement techniques and describe normal and abnormal contrast enhancement in the horse's head.
  
  
  RESULTS
  All 24 horses included in the study recovered without complication from the procedures. Compared to the pre-contrast studies, post-contrast studies showed significant contrast enhancement in the pituitary gland (IA: p < 0.0001; IV: p < 0.0001), IA nose septum (p = 0.002), nose mucosa (IA: p < 0.0001; IV: p = 0.02), parotid salivary gland (IA: p < 0.0001; IV p < 0.0001), cerebrum (IA: p < 0.0001; IV: p < 0.0001), rectus capitis muscle (IA: p < 0.0001; IV p = 0.001), IA temporal muscle (p < 0.0001), IA masseter muscle (p <0.0001) and IV brainstem (p = 0.01). No significant contrast enhancement was seen in the eye (IA: p = 0.23; IV p = 0.33), tongue (IA p = 0.2; IV p = 0.57), IA brainstem (p = 0.88), IV nose septum (p = 0.26), IV temporal muscle (p = 0.09) and IV masseter muscle (p = 0.46). Three different categories of abnormal enhancement were detected: a strong vascularised mass, an enhanced rim surrounding an unenhanced structure and an inflamed anatomical structure with abnormal contrast enhancement.
  
  
  CONCLUSIONS
  Using the intra-arterial technique, similar contrast enhancement is achieved using less contrast medium compared to the intravenous technique. And a potential major advantage of the IA technique is the ability to evaluate lesions that are characterized by increased blood flow. Using the intravenous technique, a symmetrical and homogenous enhancement is achieved, however timing is more crucial and the contrast dosage is more of influence in the IV protocol. And a potential major advantage of the IV technique is the ability to evaluate lesions that are characterized by increased vascular permeability. Knowing the different normal contrast enhancement patterns will facilitate the recognition of abnormal contrast enhancements.
authors.affiliation: Department of Veterinary Medical Imaging and Small Animal Orthopaedics, Ghent University, Faculty of Veterinary Medicine, Merelbeke, Belgium. caspercrijns@me.com.
authors.forename: Casper P
authors.initials: CP
authors.lastname: Crijns
authors.affiliation: Tierärztliches Überweisungszentrum, Tenniken, Switzerland. y.baeumlin@gmail.com.
authors.forename: Yseult
authors.initials: Y
authors.lastname: Baeumlin
authors.affiliation: Department of Veterinary Medical Imaging and Small Animal Orthopaedics, Ghent University, Faculty of Veterinary Medicine, Merelbeke, Belgium. lieve.derycke@ugent.be.
authors.forename: Lieve
authors.initials: L
authors.lastname: De Rycke
authors.affiliation: Pharmaceutical Sciences, Ghent University, Ghent, Belgium. bart.broeckx@ugent.be.
authors.forename: Bart J G
authors.initials: BJ
authors.lastname: Broeckx
authors.affiliation: Surgery and anaesthesiology of large animals, Ghent University, Merelbeke, Belgium. lieven.vlaminck@ugent.be.
authors.forename: Lieven
authors.initials: L
authors.lastname: Vlaminck
authors.affiliation: Lingehoeve Diergeneeskunde, Lienden, Netherlands. hjbergman@me.com.
authors.forename: Erik H J
authors.initials: EH
authors.lastname: Bergman
authors.affiliation: Department of Veterinary Medical Imaging and Small Animal Orthopaedics, Ghent University, Faculty of Veterinary Medicine, Merelbeke, Belgium. henri.vanbree@ugent.be.
authors.forename: Henri
authors.initials: H
authors.lastname: van Bree
authors.affiliation: Department of Veterinary Medical Imaging and Small Animal Orthopaedics, Ghent University, Faculty of Veterinary Medicine, Merelbeke, Belgium. ingrid.gielen@ugent.be.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Gielen
mesh_terms: D061605:Administration, Intravenous; D000818:Animals; D003287:Contrast Media / Q000008:administration & dosage*; D006257:Head / Q000033:anatomy & histology*; D006736:Horses / Q000033:anatomy & histology*; D007269:Injections, Intra-Arterial; D014057:Tomography, X-Ray Computed / Q000379:methods / Q000662:veterinary*
chemical_list: D003287:Contrast Media