Brain Light-Tissue Interaction Modelling: Towards a non-invasive sensor for Traumatic Brain Injury

Roldán, María Teresa Milanés; Chatterjee, Subhasri; Kyriacou, P. A.

doi:10.1109/embc46164.2021.9630909

Cited by 7 publications

(4 citation statements)

References 29 publications

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“…This characteristic enables the extraction of an optical signal that is independent of blood oxygenation ( Murkin and Arango, 2009 ). Montecarlo simulation of the light-tissue interaction has demonstrated that near-infrared (NIR) light travels deeper into the head tissue when the source-detector distance is increased ( Roldan et al, 2021 ). The reflected light from extracerebral tissue reached the proximal photodetector placed 10 mm from the LEDs; and the non-absorbed light from deeper tissues travelled back to the distal photodiode placed 35 mm from the LEDs.…”

Section: Methodsmentioning

confidence: 99%

Non-invasive monitoring of intracranial pressure changes: healthy volunteers study

et al. 2023

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Objective: This research aims to evaluate the possible association between pulsatile near infrared spectroscopic waveform features and induced changes in intracranial pressure in healthy volunteers.Methods: An optical intracranial pressure sensor was attached to the forehead of 16 healthy volunteers. Pulsatile near infrared spectroscopic signals were acquired from the forehead during body position changes and Valsalva manoeuvers. Features were extracted from the pulsatile signals and analyses were carried out to investigate the presence of statistical differences in the features when intracranial pressure changes were induced. Classification models were developed utilizing the features extracted from the pulsatile near-infrared spectroscopic signals to classify between different body positions and Valsalva manoeuvre.Results: The presence of significant differences in the majority of the analyzed features (p < 0.05) indicates the technique’s ability to distinguish between variations in intracranial pressure. Furthermore, the disparities observed in the optical signal features captured by the proximal and distal photodetectors support the hypothesis that alterations in back-scattered light directly correspond to brain-related changes. Further research is required to subtract distal and proximal signals and construct predictive models employing a gold standard measurement for non-invasive, continuous monitoring of intracranial pressure.Conclusion: The study investigated the use of pulsatile near infrared spectroscopic signals to detect changes in intracranial pressure in healthy volunteers. The results revealed significant differences in the features extracted from these signals, demonstrating a correlation with ICP changes induced by positional changes and Valsalva manoeuvre. Classification models were capable of identifying changes in ICP using features from optical signals from the brain, with a sensitivity ranging from 63.07% to 80% and specificity ranging from 60.23% to 70% respectively. These findings underscored the potential of these features to effectively identify alterations in ICP.Significance: The study’s results demonstrate the feasibility of using features extracted from optical signals from the brain to detect changes in ICP induced by positional changes and Valsalva manoeuvre in healthy volunteers. This represents a first step towards the non-invasive monitoring of intracranial pressure.

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Section: Methodsmentioning

confidence: 99%

Non-invasive monitoring of intracranial pressure changes: healthy volunteers study

et al. 2023

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“…Therefore, it is the perfect point to record an optical signal independent of blood oxygenation that could be correlated to intracranial volumetric changes. Moreover, as explained in a previous Monte Carlo simulation paper [46], a higher source-detector (S-D) distance allows light to travel deeper into the tissue; hence, pulsatile signals from a photodiode located at 2.8 mm should relate to volumetric information from the cerebral tissue. The optical signal was acquired through an in-house instrumentation system connected to a NI DAQ for analogueto-digital conversion.…”

Section: Signal Acquisition Systemmentioning

confidence: 99%

Head Phantom for the Acquisition of Pulsatile Optical Signals for Traumatic Brain Injury Monitoring

Roldán

Kyriacou

2023

Photonics

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(1) Background: Tissue phantoms can provide a rigorous, reproducible and convenient approach to evaluating an optical sensor’s performance. The development, characterisation and evaluation of a vascular head/brain phantom is described in this study. (2) Methods: The methodology includes the development of mould-cast and 3D-printed anatomical models of the brain and the skull and a custom-made in vitro blood circulatory system used to emulate haemodynamic changes in the brain. The optical properties of the developed phantom were compared to literature values. Artificial cerebrospinal fluid was also incorporated to induce changes in intracranial pressure. (3) Results: A novel head model was successfully developed to mimic the brain and skull anatomies and their optical properties within the near-infrared range (660–900 nm). The circulatory system developed mimicked normal arterial blood pressure values, with a mean systole of 118 ± 8.5 mmHg and diastole of 70 ± 8.5 mmHg. Similarly, the cerebrospinal fluid circulation allowed controlled intracranial pressure changes from 5 to 30 mmHg. Multiwavelength pulsatile optical signals (photoplethysmograms (PPGs)) from the phantom’s cerebral arteries were successfully acquired. Conclusions: This unique head phantom technology forms the basis of a novel research tool for investigating the relationship between cerebral pulsatile optical signals and changes in intracranial pressure and brain haemodynamics.

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“…Previous evaluation of infrared light and cerebral tissue interaction at different sourcedetector (S-D) separations showed that higher S-D separation increases the penetration depth, but it also causes a decrease in the overall signal quality due to high absorption [21]. Accordingly, the probe design was subdivided into two individual sub-probes called proximal probe and distal probe (Figure 1).…”

Section: Optical Partsmentioning

confidence: 99%

A Non-Invasive Optical Multimodal Photoplethysmography-Near Infrared Spectroscopy Sensor for Measuring Intracranial Pressure and Cerebral Oxygenation in Traumatic Brain Injury

Roldán

Kyriacou

2023

Applied Sciences

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(1) Background: Traumatic brain injuries (TBI) result in high fatality and lifelong disability rates. Two of the primary biomarkers in assessing TBI are intracranial pressure (ICP) and brain oxygenation. Both are assessed using standalone techniques, out of which ICP can only be assessed utilizing invasive techniques. The motivation of this research is the development of a non-invasive optical multimodal monitoring technology for ICP and brain oxygenation which will enable the effective management of TBI patients. (2) Methods: a multiwavelength optical sensor was designed and manufactured so as to assess both parameters based on the pulsatile and non-pulsatile signals detected from cerebral backscatter light. The probe consists of four LEDs and three photodetectors that measure photoplethysmography (PPG) and near-infrared spectroscopy (NIRS) signals from cerebral tissue. (3) Results: The instrumentation system designed to acquire these optical signals is described in detail along with a rigorous technical evaluation of both the sensor and instrumentation. Bench testing demonstrated the right performance of the electronic circuits while a signal quality assessment showed good indices across all wavelengths, with the signals from the distal photodetector being of highest quality. The system performed well within specifications and recorded good-quality pulsations from a head phantom and provided non-pulsatile signals as expected. (4) Conclusions: This development paves the way for a multimodal non-invasive tool for the effective assessment of TBI patients.

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Brain Light-Tissue Interaction Modelling: Towards a non-invasive sensor for Traumatic Brain Injury

Cited by 7 publications

References 29 publications

Non-invasive monitoring of intracranial pressure changes: healthy volunteers study

Non-invasive monitoring of intracranial pressure changes: healthy volunteers study

Head Phantom for the Acquisition of Pulsatile Optical Signals for Traumatic Brain Injury Monitoring

A Non-Invasive Optical Multimodal Photoplethysmography-Near Infrared Spectroscopy Sensor for Measuring Intracranial Pressure and Cerebral Oxygenation in Traumatic Brain Injury

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