Improving neuroimaging headgear placement robustness using facial-landmark guided augmented reality
Listed in
This article is not in any list yet, why not save it to one of your lists.Abstract
Significance
Accurate and consistent probe placement is crucial in functional near-infrared spectroscopy (fNIRS) and electroencephalogram (EEG) experiments, especially in longitudinal and group-based studies. Both operator experience and subject head shape variability can affect placement accuracy.
Aim
We aim to develop an easy-to-use software, NeuroNavigatAR (NNAR), utilizing augmented reality (AR) and machine-learning to estimate and display in real-time the subject’s cranial and head landmarks to guide consistent headgear placement.
Approach
By applying a facial recognition toolbox to the image frames extracted from a video camera, we can obtain and continuously track subject-specific three-dimensional (3-D) facial landmarks. Separately, we have precomputed a robust linear transformation between facial landmarks and key cranial landmarks, including nasion and preauricular points, using a large public head-model library consisting of over 1,000 subjects. These allow us to rapidly estmate subject-specific cranial landmarks and subsequently render atlas-derived head landmarks to the subject’s camera stream.
Results
An open-source graphical user interface implementing this AR system has achieved a speed of 15 frameper-second using a laptop. A median 10-20 position error of 1.52 cm was found when using a general adult atlas, and is further reduced to 1.33 cm and 0.75 cm when using age-matched atlas models and subject-specific head surfaces, respectively. NNAR demonstrated consistent head-landmark prediction errors across repeated measurement sessions; there is also no statistically significant difference in accuracy across age groups.
Conclusions
NNAR is an easy-to-use AR headgear placement monitoring tool that is expected to significantly enhance consistency and reduce setup time for fNIRS and EEG probe donning across a wide range of studies.
