PT  - JOURNAL ARTICLE
AU  - Enrico Ravagli
AU  - Svetlana Mastitskaya
AU  - Nicole Thompson
AU  - Francesco Iacoviello
AU  - Paul R Shearing
AU  - Justin Perkins
AU  - Alexander V Gourine
AU  - Kirill Aristovich
AU  - David Holder
TI  - Imaging fascicular organization of peripheral nerves with fast neural Electrical Impedance Tomography (EIT)
AID  - 10.1101/2020.06.04.133843
DP  - 2020 Jan 01
TA  - bioRxiv
PG  - 2020.06.04.133843
4099  - http://biorxiv.org/content/early/2020/06/05/2020.06.04.133843.short
4100  - http://biorxiv.org/content/early/2020/06/05/2020.06.04.133843.full
AB  - Imaging of the compound action potential (CAP) in fascicles in peripheral nerves could help avoid side effects in neuromodulation by selective stimulation of identified fascicles. Existing methods have low resolution, limited imaging depth, or are invasive. We propose fast neural electrical impedance tomography (EIT), which allows fascicular CAP imaging with a high resolution of ∼200 μm, <1 ms. This uses a non-penetrating flexible cuff electrode array with 14 circumferential electrodes. This has been validated in rat sciatic nerve by comparison to micro-computed tomography (microCT) and histology with fluorescent dextran tracers (n=5). With EIT, there were reproducible localized changes in tissue impedance in response to stimulation of individual fascicles (tibial, peroneal and sural). The reconstructed EIT images corresponded to microCT scans and neural tracer histology, with significant separation between the fascicles (p<0.01), and no significant difference between techniques. The standard deviation from the mean fascicle position for EIT was 86 μm (6% of nerve diameter). This suggests fast neural EIT can reliably image the functional fascicular anatomy of the nerves and so aid selective neuromodulation.Competing Interest StatementThe authors have declared no competing interest.