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Song K, Xu Q, Koenig HM, Kong M, Slaughter MS, Huang Y, Clifford SP, Huang J. Validation of a Novel NeurOs Cerebral Oximetry Monitor Against the INVOS Monitor During Cardiac Surgery. J Cardiothorac Vasc Anesth 2020; 35:2009-2018. [PMID: 33218956 DOI: 10.1053/j.jvca.2020.10.043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 10/23/2020] [Accepted: 10/24/2020] [Indexed: 11/11/2022]
Abstract
OBJECTIVES To compare the performance of a novel NeurOs cerebral oximetry monitor against the INVOS monitor during the entire intraoperative phase of cardiac surgery, including periods of known fluctuation in brain oxygenation, such as preoxygenation, induction, cannulation, and cardiopulmonary bypass. DESIGN This study was a prospective, nonrandomized, healthcare-provider and outcome-assessor blinded study. SETTING Tertiary care university hospital; single institutional study. PARTICIPANTS Twenty-three patients who underwent cardiac surgery with cardiopulmonary bypass. INTERVENTIONS Both self-adhesive INVOS sensors and the assembled NeurOs sensors were placed accordingly when the patient arrived in the operating room. MEASUREMENTS AND MAIN RESULTS Ten out of 13 cases under the normal mode and eight out of the 10 cases under the high- sensitivity mode showed significant correlations between the NeurOs and INVOS groups (p < 0.05, r value from 0.24-0.88). When all cases were combined, NeurOs demonstrated significant correlation with INVOS (r = 0.5, 95% confidence interval [CI] 0.44-0.56, p < 0.01 for normal mode; r = 0.69, 95% CI 0.64 to 0.74, p < 0.01 for high-sensitivity mode) in both modes. To evaluate the data diversity, the authors performed a cluster analysis and found much less variation existed in the NeurOs normal mode when compared with INVOS (standard deviation [SD] 16.6% in INVOS, 4% in NeurOs normal mode) but similar patterns in the high-sensitivity mode (SD 17.6% in INVOS, 15.2% in NeurOs high-sensitivity mode). Bland-Altman plot analysis showed that most of the data fell between ± 1.96 SD lines, which demonstrated good consistency between these two methods under both modes of NeurOs (-28.8 to 30.8 in the normal mode; -36.6 to 32.7 in high-sensitivity mode). In the normal mode of NeurOs monitoring, receiver operating characteristic analysis suggested a 2% cutoff point was most optimal from the baseline for detecting hyperoxia (sensitivity 73%; specificity 66%) and minus 1% (sensitivity 66%; specificity 67%) for detecting hypoxia. Whereas in the high-sensitivity mode, the optimal cutoff point was 3% from baseline for detecting hyperoxia (sensitivity 75%; specificity 68%), and minus 3% for detecting hypoxia (sensitivity 90%; specificity 45%). CONCLUSIONS In conclusion, the novel NeurOs system was found to correlate with INVOS cerebral oximetry measurements during cardiac surgery.
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Affiliation(s)
- Kaicheng Song
- Department of Anesthesiology & Perioperative Medicine, University of Louisville, Louisville, KY; Department of Anesthesiology, Peking Union Medical College Hospital, Chinese Academy of Medical Science, Beijing, PR China
| | - Qian Xu
- Department of Bioinformatics and Biostatistics, SPHIS, University of Louisville, Louisville, KY
| | - Heidi M Koenig
- Department of Anesthesiology & Perioperative Medicine, University of Louisville, Louisville, KY
| | - Maiying Kong
- Department of Bioinformatics and Biostatistics, SPHIS, University of Louisville, Louisville, KY
| | - Mark S Slaughter
- Department of Cardiovascular & Thoracic Surgery, University of Louisville, Louisville, KY
| | - Yuguang Huang
- Department of Anesthesiology, Peking Union Medical College Hospital, Chinese Academy of Medical Science, Beijing, PR China
| | - Sean P Clifford
- Department of Anesthesiology & Perioperative Medicine, University of Louisville, Louisville, KY
| | - Jiapeng Huang
- Department of Anesthesiology & Perioperative Medicine, University of Louisville, Louisville, KY; Department of Cardiovascular & Thoracic Surgery, University of Louisville, Louisville, KY.
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Kim S, Kim E, Jung G, Lee S, Kim JG. The hemodynamic changes during cupping therapy monitored by using an optical sensor embedded cup. JOURNAL OF BIOPHOTONICS 2019; 12:e201800286. [PMID: 30604505 DOI: 10.1002/jbio.201800286] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 12/10/2018] [Accepted: 01/02/2019] [Indexed: 05/07/2023]
Abstract
Cupping therapy is one form of alternative medicine that is used widely across the world. Although the applications of cupping therapy including pain relief have a 1000-year history, the therapeutic effect of cupping is still questionable due to a lack of scientific evidence. Therefore, in the present study, we embedded a near-infrared spectroscopic sensor into a suction cup to monitor the hemodynamic changes on the treated site while the hemodynamics at the surrounding tissue of the cup was also simultaneously monitored by another near-infrared spectroscopic sensor. The results from 10 healthy male subjects show a dramatic increase of the oxy-hemoglobin (OHb) and deoxy-hemoglobin (RHb) concentrations at the treatment site while the OHb and RHb levels were decreased at the surrounding tissue. Moreover, after the treatment, we observed that the OHb concentrations were maintained at a higher level than before treatment at both sites, which may demonstrate how cupping therapy works for treatment. In summary, the results showed that cupping therapy increases blood volume and tissue oxygenation at the treatment site while those were slightly decreased at the surrounding tissue. This study showed that the embedding of near-infrared spectroscopy in a cupping system could offer a better understanding of the mechanism of cupping therapy.
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Affiliation(s)
- Sungchul Kim
- Department of Biomedical Science and Engineering, Institute of Integrated Technology, Gwangju Institute of Science and Technology (GIST), Gwangju, South Korea
| | - Evgenii Kim
- School of Electrical Engineering and Computer Science, Gwangju Institute of Science and Technology (GIST), Gwangju, South Korea
| | - Geunho Jung
- Department of Biomedical Science and Engineering, Institute of Integrated Technology, Gwangju Institute of Science and Technology (GIST), Gwangju, South Korea
| | - Sanghun Lee
- Korea Medicine Fundamental Research Division, Korea Institute of Oriental Medicine, Daejeon, South Korea
| | - Jae G Kim
- Department of Biomedical Science and Engineering, Institute of Integrated Technology, Gwangju Institute of Science and Technology (GIST), Gwangju, South Korea
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Hernandez-Martin E, Marcano F, Modroño-Pascual C, Casanova-González O, Plata-Bello J, González-Mora JL. Is it possible to measure hemodynamic changes in the prefrontal cortex through the frontal sinus using continuous wave DOT systems? BIOMEDICAL OPTICS EXPRESS 2019; 10:817-837. [PMID: 30800517 PMCID: PMC6377888 DOI: 10.1364/boe.10.000817] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 12/11/2018] [Accepted: 12/23/2018] [Indexed: 05/20/2023]
Abstract
The present work shows the capability of near infrared (NIR) light to reach the cerebral cortex through the frontal sinus using continuous-wave techniques (CW-DOT) in a dual study. On the one hand, changes in time during the tracking of a blood dye in the prefrontal cortex were monitored. On the other hand, hemodynamic changes induced by low frequency of transcranial magnetic stimulation applied on the prefrontal cortex were recorded. The results show how NIR light projected through the frontal sinus reaches the cerebral cortex target, providing enough information to have a reliable measurement of cortical hemodynamic changes using CW-DOT.
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An observational study of the optimal placement of a cerebral oximeter probe to avoid the frontal sinus in children. J Clin Monit Comput 2017; 32:849-854. [PMID: 29230624 DOI: 10.1007/s10877-017-0087-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 12/01/2017] [Indexed: 10/18/2022]
Abstract
The frontal sinus is an airspace behind the brow ridge in the skull and can affect the accuracy of the regional cerebral oxygen saturation measurements. We evaluated the optimal location for placement of a cerebral oximeter probe while avoiding the frontal sinus in pediatric patients. This retrospective observational study included 203 pediatric patients aged 3-17 years who had undergone brain computed tomography from November 2010 to December 2015. The patients were divided into five subgroups based on their age. The frontal sinus height was measured from the superior orbital rim. Pneumatization of the frontal sinus was not visible in 78% (3-5 years) and 22% (6-8 years) of the patients. The mean (SD) of the frontal sinus height was 5.9 (3.4), 9.5 (4.1), 14.0 (6.2) 18.6 (8.4), and 21.1 (7.9) mm in the 3-5, 6-8, 9-11, 12-14, and 15-17 year age-groups, respectively. Age was positively correlated with the frontal sinus height (r = 0.61, P < 0.001, 95% confidence interval [CI] 0.513-0.688). A frontal sinus height shorter than 1, 2, and 3 cm were seen in 10 of 11 (91%), 69 of 74 (94%), and 108 of 118 (90%) patients aged 3-5, 6-10, and 11-17 years, respectively. When oximeter probes are applied in pediatric patients, placement based on age can help avoid the frontal sinus.
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Nawashiro H, Sato S, Kawauchi S, Takeuchi S, Nagatani K, Yoshihara N, Shinmoto H. Blood-oxygen-level-dependent (BOLD) functional magnetic resonance imaging (fMRI) during transcranial near-infrared laser irradiation. Brain Stimul 2017; 10:1136-1138. [PMID: 28870511 DOI: 10.1016/j.brs.2017.08.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 08/22/2017] [Accepted: 08/23/2017] [Indexed: 11/19/2022] Open
Affiliation(s)
- Hiroshi Nawashiro
- Division of Neurosurgery, Tokorozawa Central Hospital, 3-18-1 Kusunokidai, Tokorozawa, Saitama 359-0037, Japan.
| | - Shunichi Sato
- Division of Bioinformation and Therapeutic Systems, National Defense Medical College Research Institute, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama 359-8513, Japan.
| | - Satoko Kawauchi
- Division of Bioinformation and Therapeutic Systems, National Defense Medical College Research Institute, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama 359-8513, Japan.
| | - Satoru Takeuchi
- Department of Neurosurgery, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama 359-8513, Japan.
| | - Kimihiro Nagatani
- Department of Neurosurgery, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama 359-8513, Japan.
| | - Nobuyuki Yoshihara
- Department of Radiology, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama 359-8513, Japan.
| | - Hiroshi Shinmoto
- Department of Radiology, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama 359-8513, Japan.
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Effect of sensor location on regional cerebral oxygen saturation measured by INVOS 5100 in on-pump cardiac surgery. J Anesth 2016; 31:178-184. [DOI: 10.1007/s00540-016-2287-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Accepted: 11/19/2016] [Indexed: 11/27/2022]
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Holmgaard F, Vedel AG, Langkilde A, Nilsson JC, Ravn HB. Does depth of the frontal sinus affect near-infrared spectroscopy measurement? Perfusion 2016; 31:659-661. [PMID: 27235422 DOI: 10.1177/0267659116649425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Near-infrared spectroscopy (NIRS) is a non-invasive method that reflects real-time cerebral oxygenation (rSO2) by the use of two adhesive optodes placed on the forehead of the patient. Frontal sinuses vary anatomically and a large frontal sinus might compromise the NIRS signal since the NIRS optodes are placed at the skin surface superficial to the underlying frontal sinus. The aim of this case-series was to elucidate whether there is a difference in the obligate changes in rSO2 during cardiac surgery between patients with a small as opposed to a large anterior-posterior distance of the frontal sinus based on magnetic resonance imaging. Two matched groups with small (n = 5) vs. large (n = 5) frontal sinus (3.2 vs. 18.1 millimeters) in this case-series showed no difference in obligate changes of rSO2 (p = 0.54).
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Affiliation(s)
- Frederik Holmgaard
- 1 Department of Cardiothoracic Anesthesiology, Heart Centre, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Anne G Vedel
- 1 Department of Cardiothoracic Anesthesiology, Heart Centre, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Annika Langkilde
- 2 Department of Radiology, Diagnostic Centre, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Jens C Nilsson
- 1 Department of Cardiothoracic Anesthesiology, Heart Centre, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Hanne Berg Ravn
- 1 Department of Cardiothoracic Anesthesiology, Heart Centre, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
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Gregory AJ, Hatem MA, Yee K, Grocott HP. Optimal Placement of Cerebral Oximeter Monitors to Avoid the Frontal Sinus as Determined by Computed Tomography. J Cardiothorac Vasc Anesth 2016; 30:127-33. [DOI: 10.1053/j.jvca.2015.07.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2015] [Indexed: 11/11/2022]
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Kurihara K, Kawaguchi H, Obata T, Ito H, Okada E. Magnetic resonance imaging appropriate for construction of subject-specific head models for diffuse optical tomography. BIOMEDICAL OPTICS EXPRESS 2015; 6:3197-3209. [PMID: 26417492 PMCID: PMC4574648 DOI: 10.1364/boe.6.003197] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Revised: 07/24/2015] [Accepted: 07/24/2015] [Indexed: 06/05/2023]
Abstract
Subject-specific head models of which their geometry is based on structural magnetic resonance images are essential to accurately estimate the spatial sensitivity profiles for image reconstruction in diffuse optical tomography. T1-weighted magnetic resonance images, which are commonly used for structural imaging, are not sufficient for the threshold-based segmentation of the superficial tissues. Two types of pulse sequences, which provide a high contrast among the superficial tissues, are introduced to complement the segmentation to construct the subject-specific head models. The magnetic resonance images acquired by the proposed pulse sequences are robust to the threshold level and adequate for the threshold-based segmentation of the superficial tissues compared to the T1- and T2-weighted images. The total scan time of the proposed pulse sequences is less than one-fourth of that for the T2-weighted pulse sequence.
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Affiliation(s)
- Kazuki Kurihara
- Department of Electronics and Electrical Engineering, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, 223-8522, Japan
| | - Hiroshi Kawaguchi
- Human Informatics Research Institute, National Institute of Advanced Industrial Science and Technology, Central 6, 1-1-1 Higashi, Tsukuba, Ibaraki, 305-8566, Japan
- Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan
| | - Takayuki Obata
- Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan
- Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan
| | - Hiroshi Ito
- Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, Japan
- Advanced Clinical Research Center, Fukushima Medical University, 1 Hikarigaoka, Fukushima, 960-1295, Japan
| | - Eiji Okada
- Department of Electronics and Electrical Engineering, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, 223-8522, Japan
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Hyperostosis frontalis interna as a potential source of cerebral oximetry signal interference: A case report. Eur J Anaesthesiol 2015; 32:448-50. [PMID: 25906264 DOI: 10.1097/eja.0000000000000270] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Cerussi AE, Mishra N, You J, Bhandarkar N, Wong B. Monte Carlo modeling of light propagation in the human head for applications in sinus imaging. JOURNAL OF BIOMEDICAL OPTICS 2015; 20:035004. [PMID: 25781310 PMCID: PMC4362326 DOI: 10.1117/1.jbo.20.3.035004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2014] [Accepted: 02/05/2015] [Indexed: 06/04/2023]
Abstract
Sinus blockages are a common reason for physician visits, affecting one out of seven people in the United States, and often require medical treatment. Diagnosis in the primary care setting is challenging because symptom criteria (via detailed clinical history) plus objective imaging [computed tomography (CT) or endoscopy] are recommended. Unfortunately, neither option is routinely available in primary care. We previously demonstrated that low-cost near-infrared (NIR) transillumination correlates with the bulk findings of sinus opacity measured by CT. We have upgraded the technology, but questions of source optimization, anatomical influence, and detection limits remain. In order to begin addressing these questions, we have modeled NIR light propagation inside a three-dimensional adult human head constructed via CT images using a mesh-based Monte Carlo algorithm (MMCLAB). In this application, the sinus itself, which when healthy is a void region (e.g., nonscattering), is the region of interest. We characterize the changes in detected intensity due to clear (i.e., healthy) versus blocked sinuses and the effect of illumination patterns. We ran simulations for two clinical cases and compared simulations with measurements. The simulations presented herein serve as a proof of concept that this approach could be used to understand contrast mechanisms and limitations of NIR sinus imaging.
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Affiliation(s)
- Albert E. Cerussi
- University of California Irvine, Beckman Laser Institute, 1002 Health Sciences Road East, Irvine, California 92617, United States
| | - Nikhil Mishra
- University of California Irvine, Beckman Laser Institute, 1002 Health Sciences Road East, Irvine, California 92617, United States
| | - Joon You
- Praxis Biosciences, Irvine, California 92617, United States
| | - Naveen Bhandarkar
- University of California, Department of Head and Neck Surgery, 101 The City Drive South, Irvine, Orange, California 92868, United States
| | - Brian Wong
- University of California Irvine, Beckman Laser Institute, 1002 Health Sciences Road East, Irvine, California 92617, United States
- University of California, Department of Head and Neck Surgery, 101 The City Drive South, Irvine, Orange, California 92868, United States
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Developmental changes in frontal lobe function during a verbal fluency task: a multi-channel near-infrared spectroscopy study. Brain Dev 2014; 36:844-52. [PMID: 24512679 DOI: 10.1016/j.braindev.2014.01.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/27/2012] [Revised: 12/30/2013] [Accepted: 01/13/2014] [Indexed: 11/24/2022]
Abstract
OBJECTIVE Near-infrared spectroscopy (NIRS) is commonly used to investigate continuous changes of brain activation and has excellent time resolution. Verbal fluency task (VFT) is widely used as a neuropsychological test of frontal lobe function. The aim of this study was to investigate normal developmental change in frontal lobe function during VFT performance using multi-channel NIRS, specifically focusing on oxygenation hemoglobin (oxyHb) changes. METHODS The subjects were 9 adults and 37 childrens who were all healthy right-handed volunteers. Children were divided into four age groups (group A, 6-8 years; group B, 9-11 years; group C, 12-14 years; group D, 15-18 years). The [oxyHb] changes were measured with 22 channels of NIRS during VFT. We defined the frontopolar region as the region of interest for analysis, and calculated the Z-score to compare the data between groups. RESULTS The task performance changed with age. There were significant differences between group A and other groups. The Z-score of [oxyHb] also significantly increased with age, when comparing adults to groups A and B. The task performances decreased with time in all groups. In contrast, [oxyHb] only continued to increase in the adult group. CONCLUSION The verbal retrieval functions begin to mature in early adolescence and continue to grow up to adulthood.
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Funane T, Atsumori H, Katura T, Obata AN, Sato H, Tanikawa Y, Okada E, Kiguchi M. Quantitative evaluation of deep and shallow tissue layers' contribution to fNIRS signal using multi-distance optodes and independent component analysis. Neuroimage 2013; 85 Pt 1:150-65. [PMID: 23439443 DOI: 10.1016/j.neuroimage.2013.02.026] [Citation(s) in RCA: 118] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Accepted: 02/04/2013] [Indexed: 11/24/2022] Open
Abstract
To quantify the effect of absorption changes in the deep tissue (cerebral) and shallow tissue (scalp, skin) layers on functional near-infrared spectroscopy (fNIRS) signals, a method using multi-distance (MD) optodes and independent component analysis (ICA), referred to as the MD-ICA method, is proposed. In previous studies, when the signal from the shallow tissue layer (shallow signal) needs to be eliminated, it was often assumed that the shallow signal had no correlation with the signal from the deep tissue layer (deep signal). In this study, no relationship between the waveforms of deep and shallow signals is assumed, and instead, it is assumed that both signals are linear combinations of multiple signal sources, which allows the inclusion of a "shared component" (such as systemic signals) that is contained in both layers. The method also assumes that the partial optical path length of the shallow layer does not change, whereas that of the deep layer linearly increases along with the increase of the source-detector (S-D) distance. Deep- and shallow-layer contribution ratios of each independent component (IC) are calculated using the dependence of the weight of each IC on the S-D distance. Reconstruction of deep- and shallow-layer signals are performed by the sum of ICs weighted by the deep and shallow contribution ratio. Experimental validation of the principle of this technique was conducted using a dynamic phantom with two absorbing layers. Results showed that our method is effective for evaluating deep-layer contributions even if there are high correlations between deep and shallow signals. Next, we applied the method to fNIRS signals obtained on a human head with 5-, 15-, and 30-mm S-D distances during a verbal fluency task, a verbal working memory task (prefrontal area), a finger tapping task (motor area), and a tetrametric visual checker-board task (occipital area) and then estimated the deep-layer contribution ratio. To evaluate the signal separation performance of our method, we used the correlation coefficients of a laser-Doppler flowmetry (LDF) signal and a nearest 5-mm S-D distance channel signal with the shallow signal. We demonstrated that the shallow signals have a higher temporal correlation with the LDF signals and with the 5-mm S-D distance channel than the deep signals. These results show the MD-ICA method can discriminate between deep and shallow signals.
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Affiliation(s)
- Tsukasa Funane
- Hitachi, Ltd., Central Research Laboratory, Hatoyama, Saitama 350-0395, Japan.
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