title: In situ monitoring of electric field distribution in mouse tumor during electroporation.
abstract: OBJECTIVE
  To investigate the feasibility of magnetic resonance (MR) electric impedance tomography ( EIT electric impedance tomography ) technique for in situ monitoring of electric field distribution during in vivo electroporation of mouse tumors to predict reversibly electroporated tumor areas.
  
  
  METHODS
  All experiments received institutional animal care and use committee approval. Group 1 consisted of eight tumors that were used for determination of predicted area of reversibly electroporated tumor cells with MR EIT electric impedance tomography by using a 2.35-T MR imager. In addition, T1-weighted images of tumors were acquired to determine entrapment of contrast agent within the reversibly electroporated area. A correlation between predicted reversible electroporated tumor areas as determined with MR EIT electric impedance tomography and areas of entrapped MR contrast agent was evaluated to verify the accuracy of the prediction. Group 2 consisted of seven tumors that were used for validation of radiologic imaging with histopathologic staining. Histologic analysis results were then compared with predicted reversible electroporated tumor areas from group 1. Results were analyzed with Pearson correlation analysis and one-way analysis of variance.
  
  
  RESULTS
  Mean coverage ± standard deviation of tumors with electric field that leads to reversible electroporation of tumor cells obtained with MR EIT electric impedance tomography (38% ± 9) and mean fraction of tumors with entrapped MR contrast agent (41% ± 13) were correlated (Pearson analysis, r = 0.956, P = .005) and were not statistically different (analysis of variance, P = .11) from mean fraction of tumors from group 2 with entrapped fluorescent dye (39% ± 12).
  
  
  CONCLUSIONS
  MR EIT electric impedance tomography can be used for determining electric field distribution in situ during electroporation of tissue. Implementation of MR EIT electric impedance tomography in electroporation-based applications, such as electrochemotherapy and irreversible electroporation tissue ablation, would enable corrective interventions before the end of the procedure and would additionally improve the treatment outcome.
authors.affiliation: From the Faculty of Electrical Engineering, University of Ljubljana, Tržaška 25, SI-1000 Ljubljana, Slovenia (M.K., D.M.); Ljubljana Institute of Oncology, Ljubljana, Slovenia (B.M., M. Č., T.B.); Department of Condensed Matter Physics, Jozef Stefan Institute, Ljubljana, Slovenia (F.B., I.S.); Department of Biomedical Engineering, Kyung Hee University, Republic of Korea (I.S.); and Faculty of Health Sciences, University of Primorska, Izola, Slovenia (M.Č.).
authors.forename: Matej
authors.initials: M
authors.lastname: Kranjc
authors.forename: Boštjan
authors.initials: B
authors.lastname: Markelc
authors.forename: Franci
authors.initials: F
authors.lastname: Bajd
authors.forename: Maja
authors.initials: M
authors.lastname: Čemažar
authors.forename: Igor
authors.initials: I
authors.lastname: Serša
authors.forename: Tanja
authors.initials: T
authors.lastname: Blagus
authors.forename: Damijan
authors.initials: D
authors.lastname: Miklavčič
mesh_terms: D000818:Animals; D003287:Contrast Media / Q000008:administration & dosage; D004195:Disease Models, Animal; D018274:Electroporation / Q000379:methods*; D005240:Feasibility Studies; D005354:Fibrosarcoma / Q000473:pathology / Q000628:therapy*; D006571:Heterocyclic Compounds / Q000008:administration & dosage; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D051379:Mice; D009942:Organometallic Compounds / Q000008:administration & dosage
chemical_list: D003287:Contrast Media; D006571:Heterocyclic Compounds; D009942:Organometallic Compounds; C050823:gadolinium 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetate