A comparison of two EIT systems suitable for imaging impedance changes in epilepsy

Area of Science:

• Biomedical Engineering
• Medical Imaging
• Neuroscience

Background:

• Epilepsy diagnosis relies on localizing seizure foci.
• Electrical impedance tomography (EIT) offers functional imaging of conductivity changes.
• Current EIT systems face challenges in detecting subtle scalp voltage changes linked to internal conductivity shifts during seizures.

Purpose of the Study:

• To compare the performance of two EIT systems for presurgical epilepsy assessment.
• To evaluate the efficacy of EIT in localizing simulated epileptic foci.
• To determine the optimal EIT system and protocol for clinical use in epilepsy.

Main Methods:

• Two EIT systems, UCH Mk2.5 (32-channel) and KHU Mk1 (16-channel), were tested.
• Simulated epileptic foci (conductivity perturbations) were imaged in a saline tank with and without a human skull.
• 31-channel and 16-channel protocols were used with the UCH Mk2.5; only 16-channel with KHU Mk1.

Main Results:

• The UCH Mk2.5 with a 31-channel protocol achieved the best performance, with a localization error of 12.7% of the tank diameter.
• This level of accuracy is potentially sufficient for lateralizing epileptic activity.
• The KHU Mk1 and UCH Mk2.5 with 16 channels produced more blurred images but similar localization accuracy.

Conclusions:

• The UCH Mk2.5 system, particularly with a 31-channel protocol, demonstrates promising capabilities for epilepsy focus localization.
• EIT holds potential for clinical presurgical assessment of intractable epilepsy.
• Further research with higher electrode counts may improve image resolution and localization precision.