Real-Time Monitoring of Neurocritical Patients with Diffuse Optical Spectroscopies

Forti, Rodrigo M.; Katsurayama, Marilise; Valler, Lenise; Soto, Andrés Fabián Quiroga; Simioni, Luiz; Menko, Julien; Falcão, Antônio Luís Eiras; Li, Li Min; Mesquita, Rickson C.

doi:10.3791/61608

Cited by 2 publications

(5 citation statements)

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“…For our phantom experiments, we used a hybrid diffuse optical system developed at the University of Campinas, which is described elsewhere 38 , 39 . Briefly, the system combines a commercial FD-DOS system (Imagent, ISS) and a homemade DCS system.…”

Section: Methodsmentioning

confidence: 99%

“…3(b)] allowed for FD-DOS measurements with eight different source–detector separations (ρ=0.7, 1.2, 1.5, 1.7, 2.0, 2.2, 2.5, and 3.0 cm), and DCS measurements with four source–detector separations (ρ=0.7, 1.5, 2.0, and 2.5 cm). Prior to each experiment, the FD-DOS measurements were calibrated using three different solid phantoms, as described elsewhere 39 , 40 …”

Section: Methodsmentioning

confidence: 99%

“…For our phantom experiments, we used a hybrid diffuse optical system developed at the University of Campinas, which is described elsewhere. 38 , 39 Briefly, the system combines a commercial FD-DOS system (Imagent, ISS) and a homemade DCS system. The FD-DOS system contains 4 detectors and 32 lasers equally split among 4 wavelengths (685, 705, 750, and 830 nm).…”

Section: Methodsmentioning

confidence: 99%

“…Prior to each experiment, the FD-DOS measurements were calibrated using three different solid phantoms, as described elsewhere. 39 , 40 …”

Section: Methodsmentioning

confidence: 99%

“…Prior to each experiment, the FD-DOS measurements were calibrated using three different solid phantoms, as described elsewhere. 39,40 Using the setup described above, we performed two separate phantom experiments. In the first experiment, we measured the phantom in a homogeneous geometry (i.e., without the thin plastic film separating the layers).…”

Section: Liquid Phantom Experimentsmentioning

confidence: 99%

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Optimizing a two-layer method for hybrid diffuse correlation spectroscopy and frequency-domain diffuse optical spectroscopy cerebral measurements in adults

2023

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Significance: The sensitivity to extracerebral tissues is a well-known confounder of diffuse optics. Two-layer (2L) head models can separate cerebral signals from extracerebral artifacts, but they also carry the risk of crosstalk between fitting parameters. Aim:We aim to implement a constrained 2L head model for hybrid diffuse correlation spectroscopy (DCS) and frequency-domain diffuse optical spectroscopy (FD-DOS) data and to characterize errors in cerebral blood flow and tissue absorption with the proposed model. Approach:The algorithm uses the analytical solution of a 2L cylinder and an a priori extracerebral layer thickness to fit multidistance FD-DOS (0.8 to 4 cm) and DCS (0.8 and 2.5 cm) data, assuming homogeneous tissue reduced scattering. We characterized the algorithm's accuracy for simulated data with noise generated using a 2L slab and realistic adult head geometries and for in vitro phantom data.Results: Our algorithm recovered the cerebral flow index with 6.3 [2.8, 13.2]% and 34 [30,42]% (median absolute percent error [interquartile range]) for slab and head geometries, respectively. Corresponding errors in the cerebral absorption coefficient were 5.0 [3.0, 7.9]% and 4.6 [2.4, 7.2]% for the slab and head geometries and 8 [5, 12]% for our phantom experiment. Our results were minimally sensitive to second-layer scattering changes and were robust to cross-talk between fitting parameters. Conclusions:In adults, the constrained 2L algorithm promises to improve FD-DOS/DCS accuracy compared with the conventional semi-infinite approach.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

“…Prior to each experiment, the FD-DOS measurements were calibrated using three different solid phantoms, as described elsewhere. 39 , 40 …”

Section: Methodsmentioning

confidence: 99%

Section: Liquid Phantom Experimentsmentioning

confidence: 99%

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Optimizing a two-layer method for hybrid diffuse correlation spectroscopy and frequency-domain diffuse optical spectroscopy cerebral measurements in adults

2023

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Quantification of the Tissue Oxygenation Delay Induced by Breath-Holding in Patients with Carotid Atherosclerosis

et al. 2022

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Carotid artery stenosis (CAS) is a common vascular disease with long-term consequences for the brain. Although CAS is strongly associated with impaired cerebral hemodynamics and neurodegeneration, the mechanisms underlying hemodynamic impairment in the microvasculature remain unknown. In this work, we employed functional near-infrared spectroscopy (fNIRS) to introduce a methodological approach for quantifying the temporal delay of the evoked hemodynamic response. The method was validated during a vasodilatory task (breath-holding) in 50 CAS patients and 20 controls. Our results suggest that the hemodynamic response to breath-holding can be delayed by up to 6 s in the most severe patients, a significant increase from the median 4 s measured for the control group (p = 0.01). In addition, the fraction of brain regions that responded to the task decreased as the CAS severity increased, from a median of 90% in controls to 73% in the most severe CAS group (p = 0.04). The presence of collateral circulation increases the response to breath-holding and decreases the average time delays across the brain, although the number of communicating arteries alone cannot predict these fNIRS-based hemodynamic variables (p > 0.09). Overall, this work proposes a method to quantitatively assess impaired cerebral hemodynamics in CAS patients.

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Real-Time Monitoring of Neurocritical Patients with Diffuse Optical Spectroscopies

Cited by 2 publications

References 0 publications

Optimizing a two-layer method for hybrid diffuse correlation spectroscopy and frequency-domain diffuse optical spectroscopy cerebral measurements in adults

Optimizing a two-layer method for hybrid diffuse correlation spectroscopy and frequency-domain diffuse optical spectroscopy cerebral measurements in adults

Quantification of the Tissue Oxygenation Delay Induced by Breath-Holding in Patients with Carotid Atherosclerosis

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