Determining changes in NIR absorption using a layered model of the human head

Steinbrink, Jens; Wabnitz, Heidrun; Obrig, Hellmuth; Villringer, Arno; Rinneberg, H.

doi:10.1088/0031-9155/46/3/320

Cited by 243 publications

(202 citation statements)

References 25 publications

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“…This is a reasonable assumption with regards to piglets and human neonates as their skulls are relatively thin, but a poor assumption with regards to adults (Cooper et al, 1996). It has been shown that over 50% of the illuminated tissue volume in adults can be comprised of extra-cerebral tissue (Steinbrink et al, 2001). This signal contamination has been shown to cause a significant underestimation of CBF, and presumably the same would apply to CMRO 2 (Gora et al, 2002).…”

Section: Discussionmentioning

confidence: 99%

Measurement of Cerebral Oxidative Metabolism with Near-Infrared Spectroscopy: A Validation Study

Tichauer

Hadway

Lee

et al. 2005

J Cereb Blood Flow Metab

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Predicting the onset of secondary energy failure after a hypoxic-ischemic insult in newborns is critical for providing effective treatment. Measuring reductions in the cerebral metabolic rate of oxygen (CMRO 2 ) may be one method for early detection, as hypoxia-ischemia is believed to impair oxidative metabolism. We have developed a near-infrared spectroscopy (NIRS) technique based on the Fick Principle for measuring CMRO 2 . This technique combines cerebral blood flow (CBF) measurements obtained using the tracer indocyanine green with measurements of the cerebral deoxy-hemoglobin (Hb) concentration. In this study, NIRS measurements of CMRO 2 were compared with CMRO 2 determined from the product of CBF and the cerebral arteriovenous difference in oxygen measured from blood samples. The blood samples were collected from a peripheral artery and the sagittal sinus. Eight piglets were subjected to five cerebral metabolic states created by varying the plane of anesthesia. No significant difference was found between CMRO 2 measurements obtained with the two techniques at any anesthetic level (P > 0.5). Furthermore, there was a strong correlation when concomitant CMRO 2 values from the two techniques were compared (R 2 = 0.88, P < 0.001). This work showed that CMRO 2 can be determined accurately by combining NIRS measurements of CBF and Hb. Since NIRS is safe and measurements can be obtained at the bedside, it is believed that this technique could assist in the early diagnosis of cerebral energy dysfunction after hypoxia-ischemia.

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Section: Discussionmentioning

confidence: 99%

Measurement of Cerebral Oxidative Metabolism with Near-Infrared Spectroscopy: A Validation Study

Tichauer

Hadway

Lee

et al. 2005

J Cereb Blood Flow Metab

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“…4c, which shows comparable amplitudes for the same absorption change in two different locations. Further improvement in quantification requires better depth resolution, as can be provided by time-domain measurements (Kohl-Bareis et al, 2002;Steinbrink et al, 2001) or by prior spatial information from structural and functional MRI. Further discussion of time-domain methods for imaging brain activation falls outside of the scope of this paper.…”

Section: Partial Volume Errorsmentioning

confidence: 99%

Diffuse optical imaging of brain activation: approaches to optimizing image sensitivity, resolution, and accuracy

2004

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Near-infrared spectroscopy (NIRS) and diffuse optical imaging (DOI) are finding widespread application in the study of human brain activation, motivating further application-specific development of the technology. NIRS and DOI offer the potential to quantify changes in deoxyhemoglobin (HbR) and total hemoglobin (HbT) concentration, thus enabling distinction of oxygen consumption and blood flow changes during brain activation. While the techniques implemented presently provide important results for cognition and the neurosciences through their relative measures of HbR and HbT concentrations, there is much to be done to improve sensitivity, accuracy, and resolution. In this paper, we review the advances currently being made and issues to consider for improving optical image quality. These include the optimal selection of wavelengths to minimize random and systematic error propagation in the calculation of the hemoglobin concentrations, the filtering of systemic physiological signal clutter to improve sensitivity to the hemodynamic response to brain activation, the implementation of overlapping measurements to improve image spatial resolution and uniformity, and the utilization of spatial prior information from structural and functional MRI to reduce DOI partial volume error and improve image quantitative accuracy. D 2004 Elsevier Inc. All rights reserved.

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“…The changes in oxygenation are calculated from changes in attenuation at different wavelengths. This spectroscopic approach can be applied to the intensity and the mean TOF data, which have been shown to be differentially sensitive to changes in deeper layers of the tissue (Steinbrink et al, 2001b). The oxygenation response typically expected over an activated cortical area consists of a -decrease in [deoxy-Hb], accompanied by an -increase in [oxy-Hb], of 2-to 3-fold magnitude, thus resulting in an -increase in total hemoglobin ([tot-Hb]).…”

Section: Physiology Of the Signalmentioning

confidence: 99%

Beyond the Visible—Imaging the Human Brain with Light

Obrig

Villringer

2003

J Cereb Blood Flow Metab

553

215

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Summary:Optical approaches to investigate cerebral function and metabolism have long been applied in invasive studies. From the neuron cultured in vitro to the exposed cortex in the human during neurosurgical procedures, high spatial resolution can be reached and several processes such as membrane potential, cell swelling, metabolism of mitochondrial chromophores, and vascular response can be monitored, depending on the respective preparation. The authors focus on an extension of optical methods to the noninvasive application in the human. Starting with the pioneering work of Jöbsis 25 years ago, nearinfrared spectroscopy (NIRS) has been used to investigate functional activation of the human cerebral cortex. Recently, several groups have started to use imaging systems that allow the generation of images of a larger area of the subject's head and, thereby, the production of maps of cortical oxygenation changes. Such images have a much lower spatial resolution compared with the invasively obtained optical images. The noninvasive NIRS images, however, can be obtained in undemanding set-ups that can be easily combined with other functional methods, in particular EEG. Moreover, NIRS is applicable to bedside use. The authors briefly review some of the abundant literature on intrinsic optical signals and the NIRS imaging studies of the past few years. The weaknesses and strengths of the approach are critically discussed. The authors conclude that NIRS imaging has two major advantages: it can address issues concerning neurovascular coupling in the human adult and can extend functional imaging approaches to the investigation of the diseased brain. Key Words: Near-infrared spectroscopy-Cerebral oxygenation-Vascular imagingNoninvasive.The first investigations into the functional anatomy of the human cerebral cortex were based on lesion studies. The role of specific cortical areas involved in a specific task was inferred by comparing a patient's dysfunction to the lesion seen at autopsy (Fig. 1A). Whereas initially only electrophysiologic techniques allowed noninvasive functional studies of the human brain, the advent of modern imaging techniques such as functional magnetic resonance imaging (fMRI) and positron emission tomography (PET) have increasingly dominated the field during the past decade. The great advantage is the spatial resolution, which for fMRI is steadily improving and may even allow the differentiation of different cortical layers.There is an increasing need, however, for a better understanding of the signal physiology, in particular of blood oxygenation level-dependent (BOLD) contrast, since the basic principles of the coupling between the neuronal and the vascular response to functional stimulation are still not fully understood (Villringer and Dirnagl, 1995).In the present article we focus on noninvasive imaging approaches in the human using light. Near-infrared spectroscopy (NIRS),* the technique on which such imaging approaches are based, has been covered in previous articles that reviewed its potential...

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Determining changes in NIR absorption using a layered model of the human head

Cited by 243 publications

References 25 publications

Measurement of Cerebral Oxidative Metabolism with Near-Infrared Spectroscopy: A Validation Study

Measurement of Cerebral Oxidative Metabolism with Near-Infrared Spectroscopy: A Validation Study

Diffuse optical imaging of brain activation: approaches to optimizing image sensitivity, resolution, and accuracy

Beyond the Visible—Imaging the Human Brain with Light

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