title: Computed tomographic and histological findings of Hansen type I intervertebral disc herniation in dogs.
abstract: OBJECTIVE
  To evaluate whether non-contrast-enhanced computed tomography (CT) as a stand-alone imaging modality can be used to define the Hansen type I intervertebral disc herniation (IVDH) lesion and also whether the Hounsfield unit (HU) value of herniated disc is relevant to clinical duration and to histopathological chronicity of extruded disc material.
  
  
  METHODS
  Information from a series of CT studies performed on 45 dogs with a presumptive diagnosis of Hansen type I IVDH was used. Clinical duration of IVDH was estimated based on time from onset of signs per owner communication to time of surgical intervention. Hansen type I IVDH was confirmed at surgery. Retrieved herniated disc was histologically examined. The HU values were analyzed to correlate the clinical duration and histopathological chronicity of the disc lesion.
  
  
  RESULTS
  Non-contrast-enhanced CT provided sufficient diagnostic information to plan surgery in 42 of 45 dogs (93%). The value of the HU was significantly higher in clinically chronic cases (n = 12) compared to peracute cases (n = 11) (p <0.05). The HU values were significantly correlated with clinical duration (r = 0.482, p = 0.0008) and histopathological chronicity of the herniated disc (r = 0.408, p = 0.0056).
  
  
  CONCLUSIONS
  Consistent with the previous reports, the use of non-contrast-enhanced CT alone was sufficient for the diagnosis and surgical planning in most patients with Hansen type I IVDH in the thoracolumbar spine. In addition, the present study suggested that HU values on CT images may be useful in the evaluation of disease chronicity of IVDH.
authors.affiliation: Keiichi Kuroki, DVM, PhD, DACVP, 1600 East Rollins, Veterinary Medical Diagnostic Laboratory, University of Missouri, Columbia, MO 65211, United States, Phone: +1 573 882 6811, Fax: +1 573 882 1411, E-mail: kurokik@missouri.edu.
authors.forename: K
authors.initials: K
authors.lastname: Kuroki
authors.forename: C L
authors.initials: CL
authors.lastname: Vitale
authors.forename: S C
authors.initials: SC
authors.lastname: Essman
authors.forename: P
authors.initials: P
authors.lastname: Pithua
authors.forename: J R
authors.initials: JR
authors.lastname: Coates
mesh_terms: D000818:Animals; D003287:Contrast Media / Q000008:administration & dosage*; D004283:Dog Diseases / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D004285:Dogs; D005260:Female; D007405:Intervertebral Disc Displacement / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery / Q000662:veterinary*; D008297:Male; D011859:Radiography
chemical_list: D003287:Contrast Media
keywords: Histopathology; Hounsfield units; computed tomography; dog; intervertebral disc herniation