Mitchell Robinson

Massachusetts General Hospital | MGH · Athinoula A. Martinos Center for Biomedical Imaging

Diffuse correlation spectroscopy (DCS) is an optical method that offers non-invasive assessment of blood flow in tissue through the analysis of intensity fluctuations in diffusely backscattered coherent light. The non-invasive nature of the technique has enabled several clinical applications for deep tissue blood flow measurements, including cerebr...

Speckle contrast optical spectroscopy (SCOS) is an emerging camera-based technique that can measure human cerebral blood flow (CBF) with high signal-to-noise ratio (SNR). At low photon flux levels typically encountered in human CBF measurements, camera noise and nonidealities could significantly impact SCOS measurement SNR and accuracy. Thus, a gui...

Infants born at an extremely low gestational age (ELGA, < 29 weeks) are at an increased risk of intraventricular hemorrhage (IVH), and there is a need for standalone, safe, easy-to-use tools for monitoring cerebral hemodynamics. We have built a multi-wavelength multi-distance diffuse correlation spectroscopy device (MW-MD-DCS), which utilizes time-...

Carotid endarterectomy (CEA) involves removal of plaque in the carotid artery to reduce the risk of stroke and improve cerebral perfusion. This study aimed to investigate the utility of assessing pulsatile blood volume and flow during CEA. Using a combined near-infrared spectroscopy/diffuse correlation spectroscopy instrument, pulsatile hemodynamic...

Significance The non-invasive measurement of cerebral blood flow based on diffuse optical techniques has seen increased interest as a research tool for cerebral perfusion monitoring in critical care and functional brain imaging. Diffuse correlation spectroscopy (DCS) and speckle contrast optical spectroscopy (SCOS) are two such techniques that meas...

We have developed the fiber-based speckle contrast optical spectroscopy (SCOS) system to measure human cerebral blood flow (CBF) and brain functions, and demonstrated that SCOS outperforms traditional diffuse correlation spectroscopy (DCS) systems.

The hemodynamic sources of glymphatic flow are typically measured using MRI. In this work, we demonstrate the feasibility of measuring cerebral hemodynamics through NIRS toward the goal of estimating glymphatic flux in a naturalistic setting.

We present a case study for long-term DCS monitoring of an SAH patient. This case study demonstrates that DCS is suitable for continuous bedside monitoring and that MAP is a poor marker of cerebral perfusion.

Diffuse correlation spectroscopy enables non-invasive measurements of blood flow. Recent advances have enhanced measurement capabilities using interferometric detection. In this work, we report our progress on the development of pathlength selective, interferometric diffuse correlation spectroscopy.

LW-iDCS can enable robust measurement of cerebral hemodynamics. However, LW-iDCS data requires several pre-processing steps to correct signal distortions. Here, we propose a deep-learning model based on EfficientNet to accelerate and simplify blood flow estimation.

We present a novel 16-channel system for multiplexed time-domain functional diffuse correlation spectroscopy based on a custom amplified 1064 nm laser source and SNSPD detection. We demonstrate measurements of motor and prefrontal cortex activity.

Frequency domain near-infrared spectroscopy (FD-NIRS) is often synergistically combined with diffuse correlation spectroscopy (DCS) to monitor tissue perfusion and metabolism. We demonstrate an approach for simultaneous FD-NIRS and DCS data acquisition in a realistic environment.

Non-invasive optical monitoring holds potential for assessing cerebral hemodynamics post-cardiac arrest, as shown in a porcine cardiac arrest model, highlighting its potential to enhance patient care and outcomes.

SPAD arrays have shown potential for improving SNR for diffuse correlation spectroscopy in low photon regimes. Here, we will explore different methods of integrating parallelized DCS signals in such regimes for deep blood flow extraction.

The second-generation FlexNIRS provides a 266 Hz sampling rate and hardware modifications for better form factor, wearability, and multi-modal acquisition. It is currently adopted in multiple clinical measurement campaigns focusing on pulsatile component analysis.

Significance: Combining near-infrared spectroscopy (NIRS) and diffuse correlation spectroscopy (DCS) allows for quantifying cerebral blood volume, flow, and oxygenation changes continuously and non-invasively. As recently shown, the DCS pulsatile cerebral blood flow index (pCBFi) can be used to quantify critical closing pressure (CrCP) and cerebro...

Diffuse correlation spectroscopy (DCS) is an optical technique that can be used to characterize blood flow in tissue. The measurement of cerebral hemodynamics has arisen as a promising use case for DCS, though traditional implementations of DCS exhibit suboptimal signal‐to‐noise ratio (SNR) and cerebral sensitivity to make robust measurements of ce...

Diffuse correlation spectroscopy (DCS) has emerged as a versatile, noninvasive method for deep tissue perfusion assessment using near-infrared light. A broad class of applications is being pursued in neuromonitoring and beyond. However, technical limitations of the technology as originally implemented remain as barriers to wider adoption. A wide va...

Continuous, bedside monitoring of cerebral blood flow in patients at risk for neurovascular complications has the potential to decrease morbidity and mortality. While measures of systemic physiology can be used to infer cerebral perfusion, a technology that directly and continuously measures cerebral blood flow (CBF) is needed to properly manage tr...

Time-domain diffuse correlation spectroscopy (TD-DCS) offers a novel approach to high-spatial resolution functional brain imaging based on the direct quantification of cerebral blood flow (CBF) changes in response to neural activity. However, the signal-to-noise ratio (SNR) offered by previous TD-DCS instruments remains a challenge to achieving the...

This report presents an overview of how machine learning is rapidly advancing clinical translational imaging in ways that will aid in the early detection, prediction, and treatment of diseases that threaten brain health. Towards this goal, we aresharing the information presented at a symposium, “Neuroimaging Indicators of Brain Structure and Functi...

Objective: Diffuse correlation spectroscopy (DCS) is an optical technique that allows for the non-invasive measurement of blood flow. Recent work has shown that utilizing longer wavelengths beyond the traditional NIR range provides a significant improvement to signal-to-noise ratio (SNR). However, current detectors both sensitive to longer wavelen...

Significance: The ability of diffuse correlation spectroscopy (DCS) to measure cerebral blood flow (CBF) in humans is hindered by the low signal-to-noise ratio (SNR) of the method. This limits the high acquisition rates needed to resolve dynamic flow changes and to optimally filter out large pulsatile oscillations and prevents the use of large sour...

Significance: The use of diffuse correlation spectroscopy (DCS) has shown efficacy in research studies as a technique capable of noninvasively monitoring blood flow in tissue with applications in neuromonitoring, exercise science, and breast cancer management. The ability of DCS to resolve blood flow in these tissues is related to the optical sensi...

Significance: Diffuse correlation spectroscopy (DCS) is an established optical modality that enables noninvasive measurements of blood flow in deep tissue by quantifying the temporal light intensity fluctuations generated by dynamic scattering of moving red blood cells. Compared with near-infrared spectroscopy, DCS is hampered by a limited signal-...

Intra and post-operative blood flow monitoring of tissue has been shown to be effective in the improvement of patient outcomes. Diffuse correlation spectroscopy (DCS) has been shown to be effective in measuring blood flow at the bedside, and is a useful technique in measuring cerebral blood flow (CBF) in many clinical settings. However, DCS suffers...

In-vivo, optical measurements of cerebral blood flow are confounded by superficial blood flow. Here, we present acousto-optic modulated diffuse correlation spectroscopy (AOM-DCS) for blood flow monitoring, showing good agreement between theoretical predictions and experimental results.

Time-domain diffuse correlation spectroscopy (TD-DCS) aims to increase cerebral blood flow (CBF) sensitivity by discriminating photon time of flight. We report on the optimization of the laser pulse shape to maximize TD-DCS performance.

Traumatic injury resulting in hemorrhage is a prevalent cause of death worldwide. The current standard of care for trauma patients is to restore hemostasis by controlling bleeding and administering intravenous volume resuscitation. Adequate resuscitation to restore tissue blood flow and oxygenation is critical within the first hours following admis...

The quantification of visceral organ oxygenation after trauma-related systemic hypovolemia and shock is critical to enable effective resuscitation. In this work, a photoplethysmography-based (PPG) sensor was specifically designed for probing the perfusion and oxygenation condition of intestinal tissue with the ultimate goal to monitor patients post...

Blood, saliva, mucus, sweat, sputum, and other biological fluids are often hindered in their ability to be used in point-of-care (POC) diagnostics because their assays require some form of off-site sample pre-preparation to effectively separate biomarkers from larger components such as cells. The rapid isolation, identification, and quantification...

Monte Carlo modeling of photon propagation has been used in the examination of particular areas of the body to further enhance the understanding of light propagation through tissue. This work seeks to improve upon the established simulation methods through more accurate representations of the simulated tissues in the wrist as well as the characteri...

Contact heat evoked potentials (CHEPs) represent electrical brain responses to noxious heat, and corresponding amplitudes are considered an objective correlate of perceived pain. CHEPs components (N2 and P2 waves) can vary in latency, which cancels amplitude when averaged across trials. Therefore, time-frequency analysis of the EEG signal, time-loc...

From the miniaturization of large sample processing machines to the creation of handheld point-of-care devices, microfluidics has the potential to be a powerful tool in the advancement of diagnostic technologies. Here, we compare different prototyping modalities towards the generation of an inertial microfluidic blood filter: i.e. a 'centrifuge-on-...