title: Intracranial hemorrhage alters scalp potential distribution in bioimpedance cerebral monitoring: Preliminary results from FEM simulation on a realistic head model and human subjects.
abstract: OBJECTIVE
  Current diagnostic neuroimaging for detection of intracranial hemorrhage (ICH) is limited to fixed scanners requiring patient transport and extensive infrastructure support. ICH diagnosis would therefore benefit from a portable diagnostic technology, such as electrical bioimpedance (EBI). Through simulations and patient observation, the authors assessed the influence of unilateral ICH hematomas on quasisymmetric scalp potential distributions in order to establish the feasibility of EBI technology as a potential tool for early diagnosis.
  
  
  METHODS
  Finite element method (FEM) simulations and experimental left-right hemispheric scalp potential differences of healthy and damaged brains were compared with respect to the asymmetry caused by ICH lesions on quasisymmetric scalp potential distributions. In numerical simulations, this asymmetry was measured at 25 kHz and visualized on the scalp as the normalized potential difference between the healthy and ICH damaged models. Proof-of-concept simulations were extended in a pilot study of experimental scalp potential measurements recorded between 0 and 50 kHz with the authors' custom-made bioimpedance spectrometer. Mean left-right scalp potential differences recorded from the frontal, central, and parietal brain regions of ten healthy control and six patients suffering from acute/subacute ICH were compared. The observed differences were measured at the 5% level of significance using the two-sample Welch t-test.
  
  
  RESULTS
  The 3D-anatomically accurate FEM simulations showed that the normalized scalp potential difference between the damaged and healthy brain models is zero everywhere on the head surface, except in the vicinity of the lesion, where it can vary up to 5%. The authors' preliminary experimental results also confirmed that the left-right scalp potential difference in patients with ICH (e.g., 64 mV) is significantly larger than in healthy subjects (e.g., 20.8 mV; P < 0.05).
  
  
  CONCLUSIONS
  Realistic, proof-of-concept simulations confirmed that ICH affects quasisymmetric scalp potential distributions. Pilot clinical observations with the authors' custom-made bioimpedance spectrometer also showed higher left-right potential differences in the presence of ICH, similar to those of their simulations, that may help to distinguish healthy subjects from ICH patients. Although these pilot clinical observations are in agreement with the computer simulations, the small sample size of this study lacks statistical power to exclude the influence of other possible confounders such as age, sex, and electrode positioning. The agreement with previously published simulation-based and clinical results, however, suggests that EBI technology may be potentially useful for ICH detection.
authors: Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114; Athinoula Martinos Center for Biomedical Imaging, MGH, Harvard Medical School, Boston, Massachusetts 02129; and School of Technology and Health, Royal Institute of Technology, Huddinge 141 52, Sweden.
authors: Seyed Reza
authors: SR
authors: Atefi
authors: School of Technology and Health, Royal Institute of Technology, Huddinge 141 52, Sweden and Academy of Care, Wellbeing and Working Life, University of Boras, Boras 501 90, Sweden.
authors: Fernando
authors: F
authors: Seoane
authors: Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114.
authors: Shervin
authors: S
authors: Kamalian
authors: Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114.
authors: Eric S
authors: ES
authors: Rosenthal
authors: Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114.
authors: Michael H
authors: MH
authors: Lev
authors: Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114 and Athinoula Martinos Center for Biomedical Imaging, MGH, Harvard Medical School, Boston, Massachusetts 02129.
authors: Giorgio
authors: G
authors: Bonmassar
mesh_terms: D000328:Adult; D042241:Early Diagnosis; D017097:Electric Impedance; D005240:Feasibility Studies; D005260:Female; D020342:Finite Element Analysis; D006801:Humans; D020300:Intracranial Hemorrhages / Q000175:diagnosis*; D008297:Male; D010865:Pilot Projects; D012535:Scalp