Improving Neuroanatomical Localization of fNIRS Brain Imaging in Patients with CI - OMAI 2018- The 10th International Symposium on Objective Measures in Auditory Implants

Paul. R Kileny ^1,4 Xiao-Su Hu ^1,2 Anne-Michelle Tessier ¹ Teresa Zwolan ^4,5 Jessica Kim ¹ Ioulia Kovelman ^1,3

¹Center for Human Growth and Development, University of Michigan, Michigan, USA
²Headache & Orofacial Pain Effort Lab, Biologic & Materials Sciences Department, School of Dentistry, University of Michigan, Michigan, USA
³Department of Psychology, University of Michigan, Michigan, USA
⁴Department of Otolaryngology, Head and Neck Surgery, Michigan Medicine, University of Michigan, Michigan, USA
⁵Michigan Medicine Hearing Rehabilitation Center, University of Michigan, Michigan, USA

Brain imaging of patients with cochlear implants (CI) using traditional functional magnetic resonance (fMRI) and electroencephalography (EEG), is challenging due to the ferromagnetic or electronic properties of the imaging techniques. Our team has been using a novel neuroimaging approach for CI, functional Near-Infrared Spectroscopy(fNIRS). This is an optical brain imaging technique that does not require radiation, interfere with the CI device, or pose harm to patients. In a previous study (Bisconti et al., JSLH, 2016), we examined how the brains of adults with cochlear implants (CIs) respond to spoken language tasks that underlie successful language acquisition and processing. During functional near-infrared spectroscopy imaging, CI recipients with hearing impairment (n = 10, mean age: 52.7 ± 17.3 years) and controls with normal hearing (n = 10, mean age: 50.6 ± 17.2 years) completed auditory tasks-phonological awareness and passage comprehension. The results demonstrated that CI recipients presented with an overall neurotypical pattern of activation during auditory language tasks. While fNIRS proved useful in investigating cortical activation in CI recipients ( and in another study, connectivity in patients with tinnitus), since the optical probes or “optodes” are placed on the surface of the scalp, proper configuration relative to the underlying neuro-anatomy are key to interpreting fNIRS data in terms of source localization. In our most recent studies, we aimed to improve the neuroanatomical localization for fNIRS imaging in pediatric patients with CI. We developed a digital photo based probe registration (DPPR) method. This method reconstructed 360-degree photos using an 8-megapixel camera through a linear-time incremental structure from motion algorithm, based on 150 – 200 digital photos taken from different angles. Then with five pre-defined reference points, the entire fNIRS probe set was registered onto a given brain template (e.g. MNI152 Nonlinear). We further validated the DPPR registration results by comparing them with MRI scanning based registration results respectively on a group of adults and a group of pediatric participants. Finally, we applied fNIRS imaging method to get preliminary data from 6 pre-lingually deaf pediatric patients with CI who completed a rhyme and an intonation task that specifically targeted the auditory strengths and deficits in spoken language perception through CI . The results suggested that fNIRS imaging with the new localization method is a promising improvement for studying cortical activation in CI recipients.

*Functional Near-Infrared Spectroscopy Brain Imaging Investigation of Phonological Awareness and Passage Comprehension Abilities in Adult Recipients of Cochlear Implants.
Bisconti S, Shulkin M, Hu X, Basura GJ, Kileny PR, Kovelman I. J Speech Lang Hear Res. 2016 Apr 1;59(2):239-53