Prof. Stefan A. Carp Profile

Prof. Stefan A. Carp

Associate Professor of Radiology at Athinoula A Martinos Ctr for Biomedical Imaging

SPIE Involvement:

Editorial Board Member: Neurophotonics | Author

Publications (67)

Proceedings Article | 10 June 2024 Presentation

Advances in diffuse correlation spectroscopy for functional brain imaging and clinical neuromonitoring applications

Stefan Carp

Proceedings Volume PC13025, PC130250B (2024) https://doi.org/10.1117/12.3017719

KEYWORDS: Spectroscopy, Brain imaging, Biomedical applications, Imaging spectroscopy, Nervous system, Signal to noise ratio, Superconductivity, Spatial resolution, Reflection, Red blood cells

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SPIE Journal Paper | 11 May 2024 Open Access

Functional hemodynamic imaging markers for the prediction of pathological outcomes in breast cancer patients treated with neoadjuvant chemotherapy

Bin Deng, Ailis Muldoon, Jayne Cormier, Nathaniel Mercaldo, Elizabeth Niehoff, Natalie Moffett, Mansi A. Saksena, Steven Isakoff, Stefan Carp

JBO, Vol. 29, Issue 06, 066001, (May 2024) https://doi.org/10.1117/12.10.1117/1.JBO.29.6.066001

KEYWORDS: Tumors, Breast, Digital breast tomosynthesis, Biomedical optics, Mammography, Tissues, Hemodynamics, Chemotherapy, Breast cancer, Magnetic resonance imaging

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SignificanceAchieving pathologic complete response (pCR) after neoadjuvant chemotherapy (NACT) is a significant predictor of increased likelihood of survival in breast cancer patients. Early prediction of pCR is of high clinical value as it could allow personalized adjustment of treatment regimens in non-responding patients for improved outcomes.AimWe aim to assess the association between hemoglobin-based functional imaging biomarkers derived from diffuse optical tomography (DOT) and the pathological outcome represented by pCR at different timepoints along the course of NACT.ApproachTwenty-two breast cancer patients undergoing NACT were enrolled in a multimodal DOT and X-ray digital breast tomosynthesis (DBT) imaging study in which their breasts were imaged at different compression levels. Logistic regressions were used to study the associations between DOT-derived imaging markers evaluated after the first and second cycles of chemotherapy, respectively, with pCR status determined after the conclusion of NACT at the time of surgery. Receiver operating characteristic curve analysis was also used to explore the predictive performance of selected DOT-derived markers.ResultsNormalized tumor HbT under half compression was significantly lower in the pCR group compared to the non-pCR group after two chemotherapy cycles (p=0.042). In addition, the change in normalized tumor StO2 upon reducing compression from full to half mammographic force was identified as another potential indicator of pCR at an earlier time point, i.e., after the first chemo cycle (p=0.038). Exploratory predictive assessments showed that AUCs using DOT-derived functional imaging markers as predictors reach as high as 0.75 and 0.71, respectively, after the first and second chemo cycle, compared to AUCs of 0.50 and 0.53 using changes in tumor size measured on DBT and MRI.ConclusionsThese findings suggest that breast DOT could be used to assist response assessment in women undergoing NACT, a critical but unmet clinical need, and potentially enable personalized adjustments of treatment regimens.

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Proceedings Article | 13 March 2024 Presentation

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 Robinson, Nikola Otic, Paul Beach, Mehrdad Dadgostar, Zahra Einalou, Stefan Carp, David Salat, Maria Angela Franceschini

Proceedings Volume PC12850, PC128500C (2024) https://doi.org/10.1117/12.3003292

KEYWORDS: Oximeters, Wireless communications, Wearable devices, Tissues, Spectroscopes, Signal intensity, Sampling rates, Photodiodes, Oxygen, Near infrared spectroscopy

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Proceedings Article | 13 March 2024 Presentation

Depth-enhanced diffuse correlation spectroscopy enabled by coherent gain

Mitchell Robinson, Marco Renna, Stefan Carp, Maria Angela Franceschini

Proceedings Volume PC12841, PC128410C (2024) https://doi.org/10.1117/12.3003352

KEYWORDS: Spectroscopy, Blood circulation, Tissues, Signal detection, Laser sources, Scattered light, Photons, Laser interferometry, Tissue optics, Time metrology

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Proceedings Article | 13 March 2024 Presentation

Multi-channel, long-wavelength, interferometric diffuse correlation spectroscopy for functional perfusion imaging

Mitchell Robinson, Kevin Mai, Yoonho Oh, Maria Angela Franceschini, Stefan Carp

Proceedings Volume PC12828, PC128280M (2024) https://doi.org/10.1117/12.3003364

KEYWORDS: Spectroscopy, Perfusion imaging, Interferometry, Imaging spectroscopy, Imaging systems, Multichannel imaging systems, Line scan cameras, Light sources and illumination, Quality measurement, Neuroimaging

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Proceedings Article | 13 March 2024 Presentation

Fluorescence lifetime imaging for enhanced tumor contrast using exogenous dyes

Anand T, Kumar, Rahul Pal, Thinzar Lwin, Murali Krishnamoorthy, Hannah Collins, Corey Chan, Andrey Prilutskiy, MacLean Nasrallah, Tom Dijkhuis, Stefan Carp, Yin Hung, Peter Sadow, William Faquin, Brian Nahed, Allen Feng, Kevin Emerick, J. Sven Mieog, Alexander Vahrmeijer, Karthik Rajasekaran, John Y. Lee, Kenneth Rankin, Santiago Lozano-Calderon, Mark Varvares, Kenneth Tanabe

Proceedings Volume PC12825, PC128250P (2024) https://doi.org/10.1117/12.3002108

KEYWORDS: Tumors, Tissues, Surgery, Near infrared, Fluorescence lifetime imaging, Fluorescence, Fluorescence intensity, Image-guided intervention, Contrast agents, Biological imaging

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Proceedings Article | 13 March 2024 Presentation

Wearable monitoring of water content variation in peripheral edema

So Hyun Chung, Marco Renna, Maria-Angela Franceschini, Stefan Carp

Proceedings Volume PC12838, PC1283802 (2024) https://doi.org/10.1117/12.3001723

KEYWORDS: Water content, Near infrared spectroscopy, Continuous wave operation, Tissues, Simulations, Prototyping, Lymphatic system, Wearable devices, Vascular diseases, Tissue optics

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Proceedings Article | 13 March 2024 Presentation

A 256-channel SPAD detector for time-gated fNIRS and DCS

Jonathan Richardson, Tom Cheng, George Jordy, Matthew Stamplis, Ana-Maria Mandrila Vaca, Michael Bradshaw, Erik Duerr, Marco Renna, Mitchell Robinson, Stefan Carp, Maria-Angela Franceschini

Proceedings Volume PC12828, PC128280E (2024) https://doi.org/10.1117/12.3003159

KEYWORDS: Readout integrated circuits, Silicon, Near infrared spectroscopy, Windows, Spectroscopy, Photons, Imaging spectroscopy, Functional imaging, Field programmable gate arrays, Brain

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Proceedings Article | 12 March 2024 Presentation + Paper

Camera selection for speckle contrast optical spectroscopy and validation against diffuse correlation spectroscopy

Tom Cheng, Byungchan Kim, Bernhard Zimmermann, Mitchell Robinson, Marco Renna, Stefan Carp, Maria Angela Franceschini, David Boas, Xiaojun Cheng

Proceedings Volume 12841, 1284105 (2024) https://doi.org/10.1117/12.3000411

KEYWORDS: Diffuse optical spectroscopy, Temperature control, Cerebral blood flow, Fluctuations and noise, Signal intensity, Cameras, Signal to noise ratio, Quantum reading, Speckle, Spectroscopy, Optical spectroscopy, Liquids, Quantum noise, Interference (communication), CMOS cameras

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SPIE Journal Paper | 27 January 2024 Open Access

Comparing the performance potential of speckle contrast optical spectroscopy and diffuse correlation spectroscopy for cerebral blood flow monitoring using Monte Carlo simulations in realistic head geometries

Mitchell Robinson, Tom Cheng, Marco Renna, Melissa Wu, Byungchan Kim, Xiaojun Cheng, David Boas, Maria Angela Franceschini, Stefan Carp

NPh, Vol. 11, Issue 01, 015004, (January 2024) https://doi.org/10.1117/12.10.1117/1.NPh.11.1.015004

KEYWORDS: Speckle, Monte Carlo methods, Sensors, Cameras, Pulsed laser operation, Light sources and illumination, Neurophotonics, Tissues, Signal to noise ratio, Cerebral blood flow

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SignificanceThe 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 measure complementary aspects of the fluctuating intensity signal, with DCS quantifying the temporal fluctuations of the signal and SCOS quantifying the spatial blurring of a speckle pattern. With the increasing interest in the use of these techniques, a thorough comparison would inform new adopters of the benefits of each technique.AimWe systematically evaluate the performance of DCS and SCOS for the measurement of cerebral blood flow.ApproachMonte Carlo simulations of dynamic light scattering in an MRI-derived head model were performed. For both DCS and SCOS, estimates of sensitivity to cerebral blood flow changes, coefficient of variation of the measured blood flow, and the contrast-to-noise ratio of the measurement to the cerebral perfusion signal were calculated. By varying complementary aspects of data collection between the two methods, we investigated the performance benefits of different measurement strategies, including altering the number of modes per optical detector, the integration time/fitting time of the speckle measurement, and the laser source delivery strategy.ResultsThrough comparison across these metrics with simulated detectors having realistic noise properties, we determine several guiding principles for the optimization of these techniques and report the performance comparison between the two over a range of measurement properties and tissue geometries. We find that SCOS outperforms DCS in terms of contrast-to-noise ratio for the cerebral blood flow signal in the ideal case simulated here but note that SCOS requires careful experimental calibrations to ensure accurate measurements of cerebral blood flow.ConclusionWe provide design principles by which to evaluate the development of DCS and SCOS systems for their use in the measurement of cerebral blood flow.

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SPIE Journal Paper | 5 October 2023 Open Access

scatterBrains: an open database of human head models and companion optode locations for realistic Monte Carlo photon simulations

Melissa Wu, Roarke Horstmeyer, Stefan Carp

JBO, Vol. 28, Issue 10, 100501, (October 2023) https://doi.org/10.1117/12.10.1117/1.JBO.28.10.100501

KEYWORDS: Head, Simulations, Data modeling, Databases, Tissues, Monte Carlo methods, Sensors, Magnetic resonance imaging, Near infrared spectroscopy, Spectroscopy

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SPIE Journal Paper | 6 September 2023 Open Access

Enhancing diffuse correlation spectroscopy pulsatile cerebral blood flow signal with near-infrared spectroscopy photoplethysmography

Kuan Cheng Wu, Alyssa Martin, Marco Renna, Mitchell Robinson, Nisan Ozana, Stefan A. Carp, Maria Angela Franceschini

NPh, Vol. 10, Issue 03, 035008, (September 2023) https://doi.org/10.1117/12.10.1117/1.NPh.10.3.035008

KEYWORDS: Near infrared spectroscopy, Signal to noise ratio, Cerebral blood flow, Blood circulation, Spectroscopy, Blood, Oxygenation, Neurophotonics, Resistance, Sampling rates

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Proceedings Article | 15 June 2023 Presentation

A 256-channel SPAD detector for time-gated fNIRS and DCS

Jonathan Richardson, Tom Cheng, Marco Renna, George Jordy, Matthew Stamplis, Ana-Maria Mandrilla Vacca, Michael Bradshaw, Eric Ringdahl, Brian Aull, Megan Blackwell, Erik Duerr, Mitchell Robinson, Stefan Carp, Maria-Angelica Franceschini

Proceedings Volume PC12512, PC1251208 (2023) https://doi.org/10.1117/12.2666270

KEYWORDS: Single photon avalanche diodes, Sensors, Readout integrated circuits, Silicon, Spectroscopy, Sensor performance, Photons, Near infrared spectroscopy, Functional imaging, Field programmable gate arrays

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Proceedings Article | 28 March 2023 Open Access

First clinical results of fluorescence lifetime enhanced tumor imaging using exogenous agents (Conference Presentation) (Withdrawal Notice)

Rahul Pal, Thinzar Lwin, Murali Krishnamoorthy, Stefan Carp, Corey Chan, Maclean Nasrallah, John Y. Lee, Yin Hung, Allen Feng, Kenneth Tanabe, Eben Rosenthal, Brian Nahed, Kevin Emerick, Kenneth Rankin, Santiago Lozano-Calderon, Mark Varvares, Anand T. Kumar

Proceedings Volume PC12361, PC123610H (2023) https://doi.org/10.1117/12.2649241

KEYWORDS: Tumors, Fluorescence imaging, Fluorescence, Surgery, Molecules, Molecular photonics, Biomedical applications

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Proceedings Article | 17 March 2023 Presentation

Preliminary study of diffuse correlation spectroscopy for longitudinal monitoring of aneurysmal subarachnoid hemorrhage in the neuro-intensive care unit

Minhee Kim, Bryce Carr, David Y. Chung, Joanna Yang, John Sunwoo, Jae Gwan Kim, Maria A. Franceschini, Stefan A. Carp

Proceedings Volume 12364, 123640A (2023) https://doi.org/10.1117/12.2668722

KEYWORDS: Spectroscopy, Cerebral blood flow, Blood pressure, Blood circulation, Motion detection, Heart, Electrocardiography, Brain, Accelerometers

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Proceedings Article | 17 March 2023 Presentation

A comparison of brain perfusion sensitivity achievable by diffuse correlation spectroscopy versus speckle contrast optical spectroscopy

Stefan Carp, Michell Robinson, Xiaojun Cheng, David Boas, Maria Franceschini

Proceedings Volume 12364, 1236408 (2023) https://doi.org/10.1117/12.2650873

KEYWORDS: Speckle, Brain, Spectroscopy, Optical spectroscopy, Signal to noise ratio, Tissue optics, Skull, Monte Carlo methods, Laser speckle contrast imaging, Human subjects

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Proceedings Article | 17 March 2023 Presentation

Comparing methodologies for assessing autoregulation in a pediatric swine model using non-invasive optical measurements

Bryce Carr, Kichang Lee, Ekaterina Creed, Dibbyan Mazumder, Behzad Khajavi, Kitae Jung, Michael Silverman, Stefan Carp

Proceedings Volume 12364, 123640M (2023) https://doi.org/10.1117/12.2651036

KEYWORDS: Optical testing, Wavelets, Brain mapping, Brain, Blood pressure, Traumatic brain injury, Near infrared spectroscopy, Hemodynamics, Doppler effect, Cerebral blood flow

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Proceedings Article | 17 March 2023 Presentation

Non-invasive monitoring of cerebral hemodynamics using near-infrared spectroscopy and diffuse correlation spectroscopy during transcatheter aortic valve replacement surgery

Ailis Muldoon, Bryce Carr, Behzad Khajavi, Alyssa Martin, Mitchell Robinson, Julia Bertsch, Alexis Novak, Liza Parab, Ariel Mueller, Marissa Albanese, Jason Qu, Maria Angela Franceschini, Stefan Carp

Proceedings Volume 12364, 123640F (2023) https://doi.org/10.1117/12.2668694

KEYWORDS: Near infrared spectroscopy, Surgery, Hemodynamics, Spectroscopy, Oxygen, Injuries, Head, Electroencephalography, Doppler effect, Brain

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Proceedings Article | 7 March 2023 Presentation

Early prediction of neoadjuvant chemotherapy outcome with longitudinal breast diffuse optical tomography

Bin Deng, Ailis Muldoon, Jayne Cormier, Mansi Saksena, Steven Isakoff, Stefan Carp

Proceedings Volume PC12376, PC123760J (2023) https://doi.org/10.1117/12.2650855

KEYWORDS: Tumors, Breast, Diffuse optical tomography, Tissues, Imaging systems, Digital breast tomosynthesis, X-rays, X-ray imaging, Tissue optics, Optical imaging

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Proceedings Article | 7 March 2023 Presentation

Multistate time-multiplexed system for functional time-domain diffuse correlation spectroscopy with SNSPDs

Marco Renna, Zachary Starkweather, Mitchell Robinson, Nisan Ozana, Alyssa Martin, Stefan Carp, Maria Angela Franceschini

Proceedings Volume PC12376, PC123760D (2023) https://doi.org/10.1117/12.2650215

KEYWORDS: Spectroscopy, Brain, Signal to noise ratio, Blood circulation, Temporal resolution, Superconductors, Spatial resolution, Single photon detectors, Pulsed laser operation, Point spread functions

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Proceedings Article | 7 March 2023 Presentation

Multi-wavelength multi-distance diffuse correlation spectroscopy system for assessment of premature infants’ cerebral hemodynamics

Nikola Otic, John Sunwoo, Yujing Huang, Alyssa Martin, Mitchell Robinson, Bernhard Zimmermann, Stefan Carp, Maria Franceschini, Marco Renna

Proceedings Volume PC12376, PC123760E (2023) https://doi.org/10.1117/12.2649662

KEYWORDS: Spectroscopy, Hemodynamics, Near infrared spectroscopy, Spectroscopes, Single photon detectors, Scattering, Photodetectors, Optical properties, Multiplexing, Mode conditioning cables

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SPIE Journal Paper | 24 January 2023 Open Access

Diffuse correlation spectroscopy: current status and future outlook

Stefan A. Carp, Mitchell B. Robinson, Maria A. Franceschini

NPh, Vol. 10, Issue 01, 013509, (January 2023) https://doi.org/10.1117/12.10.1117/1.NPh.10.1.013509

KEYWORDS: Signal to noise ratio, Spectroscopy, Brain, Tissues, Near infrared spectroscopy, Source detector separation, Autocorrelation, Signal detection, Monte Carlo methods, Magnetic resonance imaging

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SPIE Journal Paper | 30 August 2022 Open Access

Optical imaging and spectroscopy for the study of the human brain: status report

Hasan Ayaz, Wesley Baker, Giles Blaney, David Boas, Heather Bortfeld, Kenneth Brady, Joshua Brake, Sabrina Brigadoi, Erin M. Buckley, Stefan Carp, Robert Cooper, Kyle Cowdrick, Joseph Culver, Ippeita Dan, Hamid Dehghani, Anna Devor, Turgut Durduran, Adam Eggebrecht, Lauren Emberson, Qianqian Fang, Sergio Fantini, Maria Angela Franceschini, Jonas Fischer, Judit Gervain, Joy Hirsch, Keum-Shik Hong, Roarke Horstmeyer, Jana Kainerstorfer, Tiffany Ko, Daniel Licht, Adam Liebert, Robert Luke, Jennifer Lynch, Jaume Mesquida, Rickson Mesquita, Noman Naseer, Sergio Novi, Felipe Orihuela-Espina, Thomas O'Sullivan, Darcy Peterka, Antonio Pifferi, Luca Pollonini, Angelo Sassaroli, João Ricardo Sato, Felix Scholkmann, Lorenzo Spinelli, Vivek Srinivasan, Keith St. Lawrence, Ilias Tachtsidis, Yunjie Tong, Alessandro Torricelli, Tara Urner, Heidrun Wabnitz, Martin Wolf, Ursula Wolf, Shiqi Xu, Changhuei Yang, Arjun Yodh, Meryem Yücel, Wenjun Zhou

NPh, Vol. 9, Issue S2, S24001, (August 2022) https://doi.org/10.1117/12.10.1117/1.NPh.9.S2.S24001

KEYWORDS: Brain, Near infrared spectroscopy, Neuroimaging, Imaging spectroscopy, Sensors, Optical imaging, Optical spectroscopy imaging, Optical spectroscopy, Spectroscopy, Tissue optics

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Proceedings Article | 30 May 2022 Presentation

Monitoring cerebral blood flow with superconducting nanowire detectors

Maria Franceschini, Nisan Ozana, Mitchell Robinson, Megan Blackwell, Stefan Carp, Marco Renna

Proceedings Volume PC12089, PC1208907 (2022) https://doi.org/10.1117/12.2622923

KEYWORDS: Superconductors, Sensors, Nanowires, Cerebral blood flow, Signal to noise ratio, Near infrared spectroscopy, Photon counting, Traumatic brain injury, Spectroscopy, Speckle

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Proceedings Article | 30 May 2022 Presentation

A novel 32x32 InP/ InGaAs SPAD array for multi-channel time-gated diffuse correlation spectroscopy

Marco Renna, Jonathan Richardson, George Jordy, Tom Cheng, Eric Ringdahl, Mitchell Robinson, Nisan Ozana, Niyom Lue, Brian Aull, Stefan Carp, Erik Duerr, Maria Angela Franceschini, Megan Blackwell

Proceedings Volume PC12089, PC120890E (2022) https://doi.org/10.1117/12.2619112

KEYWORDS: Indium gallium arsenide, Spectroscopes, Sensors, Photons, Tissue optics, Spectroscopy, Imaging systems, Head, Brain, Single photon detectors

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Proceedings Article | 2 March 2022 Presentation

Design and characterization of a multi-channel time-gated diffuse correlation spectroscopy system at 1064nm

Marco Renna, Jonathan Richardson, George Jordy, Tom Cheng, Mitchell Robinson, Nisan Ozana, Dibbyan Mazumder, Niyom Lue, Brian Aull, Bernhard Zimmerman, Stefan Carp, Erik Duerr, David Boas, Maria Angela Franceschini, Megan Blackwell

Proceedings Volume PC11959, PC1195908 (2022) https://doi.org/10.1117/12.2610207

KEYWORDS: Spectroscopes, Spectroscopy, Sensors, Photons, Imaging systems, Head, Single photon detectors, Single photon, Sensor performance, Semiconductor lasers

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SPIE Journal Paper | 17 February 2022 Open Access

Erratum: Improved accuracy of cerebral blood flow quantification in the presence of systemic physiology cross-talk using multi-layer Monte Carlo modeling

Melissa Wu, Suk-Tak Chan, Dibbyan Mazumder, Davide Tamborini, Kimberly Stephens, Bin Deng, Parya Farzam, Joyce Chu, Maria Angela Franceschini, Jason Qu, Stefan Carp

NPh, Vol. 9, Issue 01, 019801, (February 2022) https://doi.org/10.1117/12.10.1117/1.NPh.9.1.019801

KEYWORDS: Physiology, Monte Carlo methods, Cerebral blood flow, Neurophotonics, Biomedical optics, Radiology, Radio optics, Medicine

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SPIE Journal Paper | 19 August 2021 Open Access

Superconducting nanowire single-photon sensing of cerebral blood flow

Nisan Ozana, Alexander Zavriyev, Dibbyan Mazumder, Mitchell Robinson, Kutlu Kaya, Megan Blackwell, Stefan Carp, Maria Angela Franceschini

NPh, Vol. 8, Issue 03, 035006, (August 2021) https://doi.org/10.1117/12.10.1117/1.NPh.8.3.035006

KEYWORDS: Signal to noise ratio, Photons, Sensors, Brain, Superconductors, Nanowires, Cerebral blood flow, Blood circulation, Neurophotonics, Modulation

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SPIE Journal Paper | 12 August 2021 Open Access

Optimization of time domain diffuse correlation spectroscopy parameters for measuring brain blood flow

Dibbyan Mazumder, Melissa Wu, Nisan Ozana, Davide Tamborini, Maria Angela Franceschini, Stefan Carp

NPh, Vol. 8, Issue 03, 035005, (August 2021) https://doi.org/10.1117/12.10.1117/1.NPh.8.3.035005

KEYWORDS: Photons, Monte Carlo methods, Picosecond phenomena, Sensors, Head, Tissue optics, Spectroscopy, Brain, Blood circulation, Neurophotonics

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Significance: Time domain diffuse correlation spectroscopy (TD-DCS) can offer increased sensitivity to cerebral hemodynamics and reduced contamination from extracerebral layers by differentiating photons based on their travel time in tissue. We have developed rigorous simulation and evaluation procedures to determine the optimal time gate parameters for monitoring cerebral perfusion considering instrumentation characteristics and realistic measurement noise. Aim: We simulate TD-DCS cerebral perfusion monitoring performance for different instrument response functions (IRFs) in the presence of realistic experimental noise and evaluate metrics of sensitivity to brain blood flow, signal-to-noise ratio (SNR), and ability to reject the influence of extracerebral blood flow across a variety of time gates to determine optimal operating parameters. Approach: Light propagation was modeled on an MRI-derived human head geometry using Monte Carlo simulations for 765- and 1064-nm excitation wavelengths. We use a virtual probe with a source–detector separation of 1 cm placed in the pre-frontal region. Performance metrics described above were evaluated to determine optimal time gate(s) for different IRFs. Validation of simulation noise estimates was done with experiments conducted on an intralipid-based liquid phantom. Results: We find that TD-DCS performance strongly depends on the system IRF. Among Gaussian pulse shapes, ∼300 ps pulse length appears to offer the best performance, at wide gates (500 ps and larger) with start times 400 and 600 ps after the peak of the TPSF at 765 and 1064 nm, respectively, for a 1-s integration time at photon detection rates seen experimentally (600 kcps at 765 nm and 4 Mcps at 1064 nm). Conclusions: Our work shows that optimal time gates satisfy competing requirements for sufficient sensitivity and sufficient SNR. The achievable performance is further impacted by system IRF with ∼300 ps quasi-Gaussian pulse obtained using electro-optic laser shaping providing the best results.

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