The Optics at Martinos group is excited to attend and present at the SPIE Photonics West Conference on January 27th – February 1st, 2024 in San Francisco, CA! We have many conference presentations and posters to look out for, including:
27 January 2024 • 8:40 AM – 9:00 AM PST | Moscone Center, Room 303 (Level 3 South)
SPIE Conference 12838: Biophotonics in Exercise Science, Sports Medicine, Health Monitoring Technologies, and Wearables V
- Wearable monitoring of water content variation in peripheral edema
So Hyun Chung, Marco Renna, Maria-Angela Franceschini, and Stefan A. CarpPeripheral edema, also known as leg swelling, is observed frequently because of various causes such as sitting or standing for a long time, inflammation, injury or diseases in venous circulation system, lymphatic system, kidney and heart. It is also a side effect of chemotherapy or hormonal therapy. But to our knowledge, there is no wearable optical monitor that can quantify changes in the tissue water content related to edema. We have conducted simulations on the minimal number of light source-detector pairs and the wavelengths of the sources that can measure changes in the water fraction in superficial tissues within a compact form factor wearable optical sensor using continuous wave near-infrared spectroscopy (CW NIRS). The wavelength range we have investigated is from 800 to 1100 nm. We will present the results of simulations under various device configurations.
27 January 2024 • 4:30 PM – 4:50 PM PST | Moscone Center, Room 305 (Level 3 South)
SPIE Conference 12828: Neural Imaging and Sensing 2024
- A 256-channel SPAD detector for time-gated fNIRS and DCS
Tom Y. Cheng*, George Jordy, Matthew S. Stamplis, Ana-Maria Mandrila Vaca, Michael Bradshaw, Erik K. Duerr, Marco Renna, Mitchell B. Robinson, Stefan A. Carp, and Maria-Angela Franceschini
* Presented by Jonathan M. Richardson, MIT Lincoln Lab. (United States)
Functional near-infrared spectroscopy (fNIRS) and diffuse correlation spectroscopy (DCS) have shown promise as non-invasive optical methods for cerebral functional imaging. Both approaches currently have limits to sensitivity in adults. Sensitivity can be improved using temporal discrimination, where the laser excitation is of short (~400ps) duration and the detector rejects early photons that have not penetrated into the brain while maintain high sensitivity to those that have. We report here further demonstration of a high-speed Read-Out Integrated Circuit (ROIC) that integrates with a 32×32 Single-Photon Avalanche photo-Detector (SPAD) array that can be either silicon (Si, for visible to infra-red) in indium-phosphide (InP, to allow operation at 1064nm). Data is exfiltrated serially directly to an FPGA where it can be processed in real time. This presentation will include results of recent detector performance tests and phantom demonstrations using this powerful new tool.
28 January 2024 • 11:20 AM – 11:35 AM PST | Moscone Center, Room 155 (Upper Mezzanine South)
SPIE Conference 12825: Molecular-Guided Surgery: Molecules, Devices, and Applications X
- Towards intraoperative fluorescence lifetime imaging of tumors using near infrared probes
Anand T. N. Kumar, Rahul Pal, Thinzar M. Lwin, Murali N. Krishnamoorthy, Hannah R. Collins, Corey D. Chan, Andrey Prilutskiy, MacLean P. Nasrallah, Tom H. Dijkhuis, Stefan A. Carp, Yin P. Hung, Peter M. Sadow, William C. Faquin, Brian V. Nahed, Allen L. Feng, Kevin S. Emerick, J. Sven D. Mieog, Alexander L. Vahrmeijer, Karthik Rajasekaran, John Y. K. Lee, Kenneth S. Rankin, Santiago Lozano-Calderon, Mark A. Varvares, and Kenneth K. Tanabe.Oncologic surgery can greatly benefit from imaging techniques for the accurate identification of tumor-positive margins both intraoperatively and in resection specimens immediately following surgery. We have demonstrated clinically that fluorescence lifetime can significantly improve the accuracy for tumor vs. normal classification compared to fluorescence intensity in multiple cancer types using tumor targeted agents. Ongoing efforts by our group towards the translation of fluorescence lifetime imaging for intraoperative image guidance using exogenous agents will also be discussed.
28 January 2024 • 2:20 PM – 2:40 PM PST | Moscone Center, Room 305 (Level 3 South)
SPIE Conference 12828: Neural Imaging and Sensing 2024
- Multi-channel, long-wavelength, interferometric diffuse correlation spectroscopy for functional perfusion imaging
Mitchell B. Robinson, Kevin Mai, Yoonho Oh, Maria-Angela Franceschini, and Stefan A. CarpInterferometric diffuse correlation spectroscopy (iDCS) is an emerging technique that enables high quality measurements of cerebral blood flow. By including a reference arm in the optical setup, the SNR of the measured signals are improved relative to traditional DCS. We report here an expansion of our previously demonstrated 1064 nm single channel line scan camera based iDCS system to a multi-source, multiple detection channel approach to enable imaging of the brain perfusion response to functional activation. We confirm the ability to image multiple detectors on a single camera with minimal cross-talk using phantom experiments and show initial functional imaging results.
28 January 2024 • 5:30 PM – 7:00 PM PST | Moscone Center, Room 2003 (Level 2 West)
SPIE Conference 12828: Neural Imaging and Sensing 2024
- MW FlexNIRS 2.0: wearable, low-cost, LED-based, multi-wavelength NIRS oximeter for cytochrome c oxidase recovery in neonates (poster)
Nikola Otic, Kuan-Cheng Wu, Zachary Starkweather, Stefan A. Carp, Maria-Angela Franceschini, Marco Renna, and Emily M. HerzbergMonitoring cerebral metabolism, in addition to hemodynamics, can provide valuable insight into the brain health of infants. Cytochrome C Oxidase (CCO) is a key component of the electron transport chain inside mitochondria and is responsible for 95% of oxygen utilization. As such, it is a valuable biomarker of cerebral metabolism. We have redesigned our wearable, wireless, and portable cerebral oximeter, FlexNIRS, to include 8-wavelength LEDs (735-910 nm), which allows us to simultaneously measure changes in hemoglobin, as well as CCO concentration. We are currently validating the device on blood-yeast-intralipid liquid phantoms and will show results.
- scatterBrains, an open database of human head models and companion optode locations for realistic Monte Carlo photon simulations (poster)
Melissa M. Wu, Roarke Horstmeyer, and Stefan A. CarpMonte Carlo (MC) simulations are currently the gold standard in the near-infrared and diffuse correlation spectroscopy (NIRS/DCS) communities for generating light transport paths through tissue. However, realistic and diverse models which capture complex tissue layers are not easily available to all; moreover, manually placing virtual optodes on such models can be tedious and time-consuming. In this work, we provide the NIRS/DCS communities with an open, user-friendly database of realistic head models, along with companion scalp surface locations which provide full head coverage. Additionally, we provide a short processing pipeline to prepare the models and optode locations for MC simulations.
28 January 2024 • 5:30 PM – 7:00 PM PST | Moscone Center, Room 2003 (Level 2 West)
SPIE Conference 12834: Multimodal Biomedical Imaging XIX
- Global hypoperfusion leads to a mismatch in oxygen delivery and consumption in the cerebral watershed areas
Baoqiang Li, Hewei Cao, Hajime Takase, Srinivasa Rao Allu, Yimeng Wu, Yang Wang, Buyin Fu, Dan Hu, Sergei Vinogradov, Ken Arai, Eng Lo, Cenk Ayata, and Sava SakadzicWe applied 2-photon microscopy and Doppler optical-coherence-tomography to explore the distributions of microvascular blood flow and oxygenation in the “pial-collateral territory” and in the middle-cerebral-artery territory in awake mice. Our results showed that BCAS induced a significantly larger decrease in capillary RBC flux in the subcortical white matter in the watershed areas than in the gray matter in the watershed areas, as well as in the gray matter and white matter in the MCA territories. The larger reduction of microvascular blood flow in the watershed areas was associated with a significant increase in oxygen extraction fraction.
29 January 2024 • 9:50 AM – 10:10 AM PST | Moscone Center, Room 2008 (Level 2 West)
SPIE Conference 12841: Dynamics and Fluctuations in Biomedical Photonics XXI
- Depth-enhanced diffuse correlation spectroscopy enabled by coherent gain
Mitchell B. Robinson, Marco Renna, Stefan A. Carp, and Maria Angela FranceschiniDiffuse correlation spectroscopy (DCS) is an optical technique which is used to estimate blood flow in tissue through the analysis of the temporal fluctuations in light intensity. Recently, the development of interferometric techniques (iDCS/iDWS), have allowed for drastic improvement in measurement SNR. In this work, we build upon the iDCS technique by combining it with another advanced DCS modality, time-domain DCS (TD-DCS). This combination allows for the application of pathlength specific coherent gain, which has the potential to further improve the performance of DCS in the non-invasive measurement of deep tissue blood flow
29 January 2024 • 10:10 AM – 10:30 AM PST | Moscone Center, Room 2008 (Level 2 West)
SPIE Conference 12841: Dynamics and Fluctuations in Biomedical Photonics XXI
- Camera selection for speckle contrast optical spectroscopy and validation against diffuse correlation spectroscopy
Tom Y. Cheng, Byungchan Kim, Stefan Carp, Mitchell B. Robinson, David Boas, Maria Angela Franceschini, and Xiaojun ChengSpeckle contrast optical spectroscopy (SCOS) is an emerging technique to measure human cerebral blood flow (CBF) that has the potential to achieve more than an order of magnitude improvement in signal to noise ratio (SNR) and temporal resolution as compared to diffuse correlation spectroscopy (DCS). In the low photon flux regime relevant for human CBF measurements, camera nonidealities and noise can significantly impact SCOS SNR and accuracy. Thus, a guide for characterizing camera parameters relevant to SCOS and then predicting the optimal operating parameters for a given camera is crucial to the optimization of SCOS systems for measuring human CBF. In this work, we will present a) a guide for characterizing camera parameters relevant to SCOS and assessing the impact of certain camera nonidealities that are difficult to correct, b) utilize our recently developed SCOS noise model to determine the optimal operating parameters for selected cameras, and c) experimentally validate noise-corrected SCOS measurements taken with a characterized camera against simultaneous, co-located DCS measurements on a liquid phantom.
29 January 2024 • 11:20 AM – 11:40 AM PST | Moscone Center, Room 2008 (Level 2 West)
SPIE Conference 12841: Dynamics and Fluctuations in Biomedical Photonics XXI
- Capillary blood flow imaging in awake mice using dynamic light scattering OCT and two photon microscopy
Sida Liang, Qi Pian, Mohammed Alfadhel, Buyin Fu, Jianbo Tang, and Sava SakadzicAccurate assessment of cerebral microvascular flow is crucial for understanding brain functioning and neurovascular diseases. Dynamic Light Scattering Optical Coherence Tomography (DLS-OCT) has been used to obtain blood velocity measurements in a large number of microvascular segments, including arterioles, capillaries, and venules in anesthetized mice. However, anesthesia induces large changes in the microvascular blood flow. Imaging awake animals by DLS-OCT is preferable, but very challenging due to motion artifacts. Here, we present the first DLS-OCT measurements of cortical microvascular blood flow in awake mice, made possible by an innovative algorithm based on Vertical Displacement at Inflection (IVD) in velocity distribution.
30 January 2024 • 10:30 AM – 10:50 AM PST | Moscone Center, Room 2010 (Level 2 West)
SPIE Conference 12850: Optical Diagnostics and Sensing XXIV: Toward Point-of-Care Diagnostics
- FlexNIRS: current applications and latest developments of the open-source wireless wearable oximeter for cerebral health tracking
Marco Renna, Kuan-Cheng Wu, John Sunwoo, Alyssa Martin, Zachary Starkweather, Mitchell B. Robinson, Nikola Otic, Paul Beach, Mehrdad Dadgostar, Zahra Einalou, Stefan A. Carp, David Salat, and Maria Angela FranceschiniRecently we developed the open-source FlexNIRS: a battery-operated, wireless, wearable oximeter whose self-calibrating geometry allows measurements of oxygen saturation in tissue. The first implementation of the device operating at 100 Hz has been validated and is enrolled in several measurement campaigns across different research laboratories. A recent firmware upgrade provides 255 Hz sampling rate, and hardware modifications provide improved form factor, wearability, and multi-modal acquisition. The new version is currently adopted in multiple clinical measurement campaigns focusing on pulsatile component analysis. We will present the instrument performance, its recent and future upgrades, and the applications where the device is currently in use.