A review on continuous wave functional near-infrared spectroscopy and imaging instrumentation and methodology

• Published in: NeuroImage (Orlando, Fla.) Vol. 85; pp. 6 - 27
• Main Authors: Scholkmann, Felix, Kleiser, Stefan, Metz, Andreas Jaakko, Zimmermann, Raphael, Mata Pavia, Juan, Wolf, Ursula, Wolf, Martin
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 15.01.2014; Elsevier Limited
• Subjects: Brain activity; Continuous wave; FDA approval; Functional near-infrared imaging (fNIRI); Functional near-infrared spectroscopy (fNIRS); Functional Neuroimaging - instrumentation; Heart rate; Humans; Image Processing, Computer-Assisted; Infrared Rays; Instrumentation; Lasers; Light emitting diodes; Models, Statistical; Near-infrared imaging (NIRI); Near-infrared spectroscopy (NIRS); Review; Spectroscopy, Near-Infrared - instrumentation; Spectrum analysis; Studies; Germany; Functional near-infrared spectroscopy (fNIRS); Continuous wave; Brain activity; Instrumentation; Near-infrared spectroscopy (NIRS); Review; Functional near-infrared imaging (fNIRI); Near-infrared imaging (NIRI)
• ISSN: 1053-8119; 1095-9572; 1095-9572
• DOI: 10.1016/j.neuroimage.2013.05.004

This year marks the 20th anniversary of functional near-infrared spectroscopy and imaging (fNIRS/fNIRI). As the vast majority of commercial instruments developed until now are based on continuous wave technology, the aim of this publication is to review the current state of instrumentation and methodology of continuous wave fNIRI. For this purpose we provide an overview of the commercially available instruments and address instrumental aspects such as light sources, detectors and sensor arrangements. Methodological aspects, algorithms to calculate the concentrations of oxy- and deoxyhemoglobin and approaches for data analysis are also reviewed. From the single-location measurements of the early years, instrumentation has progressed to imaging initially in two dimensions (topography) and then three (tomography). The methods of analysis have also changed tremendously, from the simple modified Beer-Lambert law to sophisticated image reconstruction and data analysis methods used today. Due to these advances, fNIRI has become a modality that is widely used in neuroscience research and several manufacturers provide commercial instrumentation. It seems likely that fNIRI will become a clinical tool in the foreseeable future, which will enable diagnosis in single subjects. •Comprehensive review on continuous wave functional near infrared imaging•Overview of currently available commercial near infrared imaging instrumentation•Review of technical aspects such as light sources, detectors and sensor arrangements•Review of methodological aspects, algorithms, and data analysis and its tool boxes