In vivo imaging of epileptic foci in rats using a miniature probe integrating diffuse optical tomography and electroencephalographic source localization

Abstract

SUMMARY Objective The goal of this work is to establish a new dual-modal brain mapping technique based on diffuse optical tomography (DOT) and electroencephalographic source localization (ESL) that can chronically/intracranially record optical/EEG data to precisely map seizures and localize the seizure onset zone and associated epileptic brain network. Methods The dual-modal imaging system was employed to image seizures in an experimental acute bicuculline methiodide rat model of focal epilepsy. Depth information derived from DOT was used as constraint in ESL to enhance the image reconstruction. Groups of animals were compared based on localization of seizure foci, either at different positions or at different depths. Results This novel imaging technique successfully localized the seizure onset zone in rat induced by bicuculline methiodide injected at a depth of 1mm, 2mm and 3mm, respectively. The results demonstrated that the incorporation of the depth information from DOT into the ESL image reconstruction resulted in more accurate and reliable ESL images. Although the ESL images showed a horizontal shift of the source localization, the DOT identified the seizure focus accurately. In one case, when the BMI was injected at a site outside the field of view (FOV) of the DOT/ESL interface, ESL gives false positive detection of the focus while DOT shows negative detection. Significance This study represents the first to identify seizure onset zone using implantable DOT. In addition, the combination of DOT/ESL has never been documented in neuroscience and epilepsy imaging. This technology will enable us to precisely measure the neural activity and hemodynamic response at exactly the same tissue site and at both cortical and sub cortical levels.

Electrical Source Imaging in Freely Moving Rats: Evaluation of a 12-Electrode Cortical Electroencephalography System

“…ESI was also performed in anesthetized mice using non-invasive 40-channel micro-array EEG, and the accuracy of three inverse solutions—minimum norm estimates (MNE), multiple signal classification, and single dipole fitting—was compared using the boundary-element method based forward model (Lee et al, 2013 ). Integrating a DOT sensor and electrode array in rats, Yang et al ( 2015 ) showed that prior information obtained from the DOT may improve the accuracy of the minimum norm based solution. In a previous study on physical phantom measurements (Yang and Jiang, 2013 ), a significant bias of ESI was observed.…”

Rat Head Phantom for Testing of Electroencephalogram Source Localization Techniques

“…To achieve reliable source reconstructions, uncertainties in all of the steps have to be treated carefully [12]. Recently, source localization in rodents has been investigated for preclinical and translational research [13], [14]. Various techniques have been used for EEG acquisition: high density scalp EEG cap [13], [15], skull EEG microarray [16], and regular cortical electrode array [14].…”

Full density fluorescence molecular tomography (FD-FMT) based on a dichroic mirror

“…Another way to alleviate the ill-conditioning and improve the image quality, involves integrating FMT with other imaging technologies into a hybrid modality. The benefits of this approach have been demonstrated in recent studies for modalities such as CT, MRI, and ultrasound [16–21]. Obviously, a miniaturized FMT system offers the potential to combine it with other imaging modalities, especially in the design of miniaturized imaging devices such as endoscopes.…”