title: Use of electrical impedance tomography to monitor regional cerebral edema during clinical dehydration treatment.
abstract: OBJECTIVE
  Variations of conductive fluid content in brain tissue (e.g. cerebral edema) change tissue impedance and can potentially be measured by Electrical Impedance Tomography (EIT), an emerging medical imaging technique. The objective of this work is to establish the feasibility of using EIT as an imaging tool for monitoring brain fluid content.
  
  
  METHODS
  a prospective study.
  
  
  METHODS
  In this study EIT was used, for the first time, to monitor variations in cerebral fluid content in a clinical model with patients undergoing clinical dehydration treatment. The EIT system was developed in house and its imaging sensitivity and spatial resolution were evaluated on a saline-filled tank.
  
  
  METHODS
  23 patients with brain edema.
  
  
  METHODS
  The patients were continuously imaged by EIT for two hours after initiation of dehydration treatment using 0.5 g/kg intravenous infusion of mannitol for 20 minutes.
  
  
  RESULTS
  Overall impedance across the brain increased significantly before and after mannitol dehydration treatment (p = 0.0027). Of the all 23 patients, 14 showed high-level impedance increase and maintained this around 4 hours after the dehydration treatment whereas the other 9 also showed great impedance gain during the treatment but it gradually decreased after the treatment. Further analysis of the regions of interest in the EIT images revealed that diseased regions, identified on corresponding CT images, showed significantly less impedance changes than normal regions during the monitoring period, indicating variations in different patients' responses to such treatment.
  
  
  CONCLUSIONS
  EIT shows potential promise as an imaging tool for real-time and non-invasive monitoring of brain edema patients.
authors.affiliation: Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Fu
authors.affiliation: Neurosurgical Unit of Xijing Hospital, Fourth Military Medical University, Xi'an, China.
authors.forename: Bing
authors.initials: B
authors.lastname: Li
authors.affiliation: Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China.
authors.forename: Meng
authors.initials: M
authors.lastname: Dai
authors.affiliation: Neurosurgical Unit of Xijing Hospital, Fourth Military Medical University, Xi'an, China.
authors.forename: Shi-Jie
authors.initials: SJ
authors.lastname: Hu
authors.affiliation: Neurosurgical Unit of Xijing Hospital, Fourth Military Medical University, Xi'an, China.
authors.forename: Xia
authors.initials: X
authors.lastname: Li
authors.affiliation: Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China.
authors.forename: Can-Hua
authors.initials: CH
authors.lastname: Xu
authors.affiliation: Neurosurgical Unit of Xijing Hospital, Fourth Military Medical University, Xi'an, China.
authors.forename: Bing
authors.initials: B
authors.lastname: Wang
authors.affiliation: Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Yang
authors.affiliation: Department of Bioengineering, Imperial College London, London, United Kingdom.
authors.forename: Meng-Xing
authors.initials: MX
authors.lastname: Tang
authors.affiliation: Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China.
authors.forename: Xiu-Zhen
authors.initials: XZ
authors.lastname: Dong
authors.affiliation: Neurosurgical Unit of Xijing Hospital, Fourth Military Medical University, Xi'an, China.
authors.forename: Zhou
authors.initials: Z
authors.lastname: Fei
authors.affiliation: Department of Biomedical Engineering, Fourth Military Medical University, Xi'an, China.
authors.forename: Xue-Tao
authors.initials: XT
authors.lastname: Shi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000187:drug effects / Q000503:physiopathology; D001929:Brain Edema / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000628:therapy*; D001930:Brain Injuries / Q000000981:diagnostic imaging* / Q000628:therapy; D017097:Electric Impedance; D045604:Extracellular Fluid; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008353:Mannitol / Q000008:administration & dosage; D008875:Middle Aged; D014057:Tomography, X-Ray Computed
chemical_list: D008353:Mannitol