Magnetic Resonance Imaging Characteristics of Nonthermal Irreversible Electroporation in Vegetable Tissue Mohammad Hjouj • Boris Rubinsky Received: 23 December 2009 / Accepted: 22 June 2010 / Published online: 15 July 2010 Ó Springer Science+Business Media, LLC 2010 Abstract We introduce and characterize the use of MRI for studying nonthermal irreversible electroporation (NTIRE) in a vegetative tissue model. NTIRE is a new minimally invasive surgical technique for tissue ablation in which microsecond, high electric-field pulses form nano- scale defects in the cell membrane that lead to cell death. Clinical NTIRE sequences were applied to a potato tuber tissue model. The potato is used for NTIRE studies because cell damage is readily visible with optical means through a natural oxidation process of released intracellular enzymes (polyphenol oxidase) and the formation of brown-black melanins. MRI sequences of the treated area were taken at various times before and after NTIRE and compared with photographic images. A comparison was made between T1W, T2W, FLAIR and STIR MRIs of NTIRE and pho- tographic images. Some MRI sequences show changes in areas treated by irreversible electroporation. T1W and FLAIR produce brighter images of the treated areas. In contrast, the signal was lost from the treated area when a suppression technique, STIR, was used. There was simi- larity between optical photographic images of the treated tissue and MRIs of the same areas. This is the first study to characterize MRI of NTIRE in vegetative tissue. We find that NTIRE produces changes in vegetative tissue that can be imaged by certain MRI sequences. This could make MRI an effective tool to study the fundamentals of NTIRE in nonanimal tissue. Keywords Nonthermal irreversible electroporation Á Cell membrane Á MRI Á T1-weighted Á T2-weighted Á FLAIR Á STIR Introduction Electroporation, or electropermeabilization, is the bio- physical phenomenon in which cell membrane permeabil- ity to ions and macromolecules is increased by exposing the cell to short (microsecond to millisecond) high electric- field pulses (EFPs) (Weaver 2000). The effect is related to the formation of defects (pores) in the cell membrane (Neumann et al. 1982). EFPs that induce electroporation in which defects reseal after the application of the pulse and the cells survive are known to cause ‘‘reversible electro- poration.’’ EFPs from which cells do not survive electro- poration are known to cause ‘‘irreversible electroporation.’’ Often, because of the electrical Joule heating phenomenon, irreversible electroporation EFPs also cause thermal dam- age to cells and tissues (Lee et al. 1988; Lee and Kolodney 1987). Nonthermal irreversible electroporation (NTIRE) refers to EFPs that induce irreversible electroporation without any thermal effects (Davalos et al. 2005). Other minimally invasive or noninvasive tissue ablation surgical techniques, such as radiation, cryosurgery, ultrasound, radiofrequency and microwave heating, affect indiscrimi- nately all of the molecules in the volume of treated tissue. In contrast, NTIRE affects only the cell membrane lipid bilayer. This makes NTIRE unique among technologies for tissue ablation because it can ablate cells in a volume of tissue while leaving the extracellular matrix and other cell membrane components intact. Detailed information on NTIRE can be found in a recent edited book (Rubinsky 2010). M. Hjouj (&) Á B. Rubinsky Center for Bioengineering in the Service of Humanity and Society, School of Computer Science and Engineering, Hebrew University of Jerusalem, Jerusalem, Israel e-mail: mhjouj@hotmail.com 123 J Membrane Biol (2010) 236:137–146 DOI 10.1007/s00232-010-9281-2