A Machado1, Z Cai2, G Pellegrino3, O Marcotte4, T Vincent2, J-M Lina5, E Kobayashi6, C Grova7. 1. Multimodal Functional Imaging Laboratory, Biomedical Engineering Department, McGill University, Canada. Electronic address: alexis.machado@mail.mcgill.ca. 2. Physics Department and PERFORM center, Concordia University, Montreal, Canada. 3. Multimodal Functional Imaging Laboratory, Biomedical Engineering Department, McGill University, Canada; IRCCS Fondazione Ospedale San Camillo Via Alberoni, Venice, Italy. 4. GERAD, École des HEC, Montréal, Canada; Département d'informatique, Université du Québec à Montréal, Canada; Centre de Recherches Mathématiques, Université de Montréal, Québec, Canada. 5. École de technologie supérieure de l'Université du Québec, Canada; Centre de Recherches Mathématiques, Université de Montréal, Québec, Canada. 6. Montreal Neurological Institute, Department of Neurology and Neurosurgery, McGill University, Canada. 7. Multimodal Functional Imaging Laboratory, Biomedical Engineering Department, McGill University, Canada; Physics Department and PERFORM center, Concordia University, Montreal, Canada; Montreal Neurological Institute, Department of Neurology and Neurosurgery, McGill University, Canada; Centre de Recherches Mathématiques, Université de Montréal, Québec, Canada.
Abstract
BACKGROUND: Application of functional Near InfraRed Spectroscopy (fNIRS) in neurology is still limited as a good optical coupling and optimized optode coverage of specific brain regions remains challenging, notably for prolonged monitoring. METHODS: We propose to evaluate a new procedure allowing accurate investigation of specific brain regions. The procedure consists in: (i) A priori maximization of spatial sensitivity of fNIRS measurements targeting specific brain regions, while reducing the number of applied optodes in order to decrease installation time and improve subject comfort. (ii) Utilization of a 3D neuronavigation device and usage of collodion to glue optodes on the scalp, ensuring good optical contact for prolonged investigations. (iii) Local reconstruction of the hemodynamic activity along the cortical surface using inverse modelling. RESULTS: Using realistic simulations, we demonstrated that maps derived from optimal montage acquisitions showed, after reconstruction, spatial resolution only slightly lower to that of ultra high density montages while significantly reducing the number of optodes. The optimal montages provided overall good quantitative accuracy especially at the peak of the spatially reconstructed map. We also evaluated real motor responses in two healthy subjects and obtained reproducible motor responses over different sessions. COMPARISON WITH EXISTING METHODS: We are among the first to propose a mathematical optimization strategy, allowing high sensitivity measurements. CONCLUSIONS: Our results support that using personalized optimal montages should allow to conduct accurate fNIRS studies in clinical settings and realistic lifestyle conditions.
BACKGROUND: Application of functional Near InfraRed Spectroscopy (fNIRS) in neurology is still limited as a good optical coupling and optimized optode coverage of specific brain regions remains challenging, notably for prolonged monitoring. METHODS: We propose to evaluate a new procedure allowing accurate investigation of specific brain regions. The procedure consists in: (i) A priori maximization of spatial sensitivity of fNIRS measurements targeting specific brain regions, while reducing the number of applied optodes in order to decrease installation time and improve subject comfort. (ii) Utilization of a 3D neuronavigation device and usage of collodion to glue optodes on the scalp, ensuring good optical contact for prolonged investigations. (iii) Local reconstruction of the hemodynamic activity along the cortical surface using inverse modelling. RESULTS: Using realistic simulations, we demonstrated that maps derived from optimal montage acquisitions showed, after reconstruction, spatial resolution only slightly lower to that of ultra high density montages while significantly reducing the number of optodes. The optimal montages provided overall good quantitative accuracy especially at the peak of the spatially reconstructed map. We also evaluated real motor responses in two healthy subjects and obtained reproducible motor responses over different sessions. COMPARISON WITH EXISTING METHODS: We are among the first to propose a mathematical optimization strategy, allowing high sensitivity measurements. CONCLUSIONS: Our results support that using personalized optimal montages should allow to conduct accurate fNIRS studies in clinical settings and realistic lifestyle conditions.
Authors: Meryem A Yücel; Alexander V Lühmann; Felix Scholkmann; Judit Gervain; Ippeita Dan; Hasan Ayaz; David Boas; Robert J Cooper; Joseph Culver; Clare E Elwell; Adam Eggebrecht; Maria A Franceschini; Christophe Grova; Fumitaka Homae; Frédéric Lesage; Hellmuth Obrig; Ilias Tachtsidis; Sungho Tak; Yunjie Tong; Alessandro Torricelli; Heidrun Wabnitz; Martin Wolf Journal: Neurophotonics Date: 2021-01-07 Impact factor: 3.593