title: Estimation of the depth of the thoracic epidural space in children using magnetic resonance imaging.
abstract: BACKGROUND
  The estimation of the distance from the skin to the thoracic epidural space or skin to epidural depth (SED) may increase the success rate and decrease the incidence of complications during placement of a thoracic epidural catheter. Magnetic resonance imaging (MRI) is the most comprehensive imaging modality of the spine, allowing for the accurate determination of tissue spaces and distances. The present study uses MRI-derived measurements to measure the SED and define the ratio between the straight and inclined SEDs at two thoracic levels (T6-7and T9-10) in children.
  
  
  METHODS
  The T2-weighed sagittal MRI images of 109 children, ranging in age from 1 month to 8 years, undergoing radiological evaluation unrelated to spine pathology were assessed. The SEDs (inclined and straight) were determined, and a comparison between the SEDs at two thoracic levels (T6-7and T9-10) was made. Univariate and multivariate linear regression models were used to assess the relationship of the inclined thoracic T6-7and T9-10SED measurements with age, height, and weight.
  
  
  RESULTS
  Body weight demonstrated a stronger association with the SED than did the age or height withR2values of 0.6 for T6-7and 0.5 for T9-10. The formulae describing the relationship between the weight and the inclined SED were T6-7inclined (mm) = 7 + 0.9 × kg and T9-10inclined (mm) = 7 + 0.8 × kg.
  
  
  CONCLUSIONS
  The depth of the pediatric thoracic epidural space shows a stronger correlation with weight than with age or height. Based on the MRI data, the predictive weight-based formulas can serve as guide to clinicians for placement of thoracic epidural catheters.
authors.affiliation: Department of Anesthesia, King Fahad Medical City, Riyadh, Saudi Arabia; Department of Anesthesiology and Pain Medicine, Nationwide Children's Hospital, Columbus, OH, USA.
authors.forename: Tariq M
authors.initials: TM
authors.lastname: Wani
authors.affiliation: Department of Anesthesia, King Fahad Medical City, Riyadh, Saudi Arabia.
authors.forename: Mahmood
authors.initials: M
authors.lastname: Rafiq
authors.affiliation: Department of Anesthesia, King Fahad Medical City, Riyadh, Saudi Arabia.
authors.forename: Arif
authors.initials: A
authors.lastname: Nazir
authors.affiliation: Department of Anesthesia, King Fahad Medical City, Riyadh, Saudi Arabia.
authors.forename: Hatem A
authors.initials: HA
authors.lastname: Azzam
authors.affiliation: Department of Anesthesia, King Fahad Medical City, Riyadh, Saudi Arabia.
authors.forename: Usama
authors.initials: U
authors.lastname: Al Zuraigi
authors.affiliation: Department of Anesthesiology and Pain Medicine, Nationwide Children's Hospital, Columbus, OH, USA.
authors.forename: Joseph D
authors.initials: JD
authors.lastname: Tobias
keywords: magnetic resonance imaging; measurement techniques; thoracic epidural space