Smartphone-driven photogrammetry to localize functional near-infrared spectroscopy channels

• Published in: Transactions of Japanese Society for Medical and Biological Engineering Vol. Annual62; no. Abstract; p. 272_2
• Main Author: 鈴木, 達也
• Format: Journal Article
• Language: Japanese
• Published: 公益社団法人 日本生体医工学会 2024; Japanese Society for Medical and Biological Engineering
• ISSN: 1347-443X; 1881-4379
• DOI: 10.11239/jsmbe.Annual62.272_2

Functional near-infrared spectroscopy (fNIRS) requires precise spatial localization of fNIRS channels. In our pursuit of a more cost-effective and widely accessible method of channel localization without manual pointing using an electromagnetic digitizer, we propose smartphone-based photogrammetry. This technique uses the built-in camera of a smartphone to create 3D models from 2D photographs. A smartphone application called ‘Scaniverse – 3D Scanner’ was used to create a 3D model of the head with an optode cap attached. We evaluated the agreement between the fNIRS channel localization methods based on photogrammetry and the conventional electromagnetic digitizer. We determined the Montreal Neurological Institute (MNI) coordinates of simulated fNIRS channels over the entire head using both methods in the same participants. The median Euclidean distance between channel positions measured by photogrammetry and the digitizer was 6.96 mm. Our results suggest the potential utility of the photogrammetry method as a cost-effective and user-friendly head digitization technique.