NEWS

Alex’s first first-author paper is published!

By Xiaojun Cheng August 6th, 2025

This work tests the linearity in SCOS measurements. It also indicates that linear methods developed for functional near infrared spectroscopy (fNIRS) can also be applied to SCOS.

Howard, Alexander C., Byungchan Kim, Laura Carlton, Meryem A. Yücel, Bingxue Liu, David A. Boas, and Xiaojun Cheng. "Validation of the Linearity in Image Reconstruction Methods for Speckle Contrast Optical Tomography." IEEE Journal of Selected Topics in Quantum Electronics (2025).

Abstract:

Speckle contrast optical spectroscopy (SCOS) is an optical technique capable of measuring human cerebral blood flow and brain function non-invasively. Its tomographic extension, speckle contrast optical tomography (SCOT), can provide blood flow variation maps with measurements using overlapping source-detector channel pairs. Linearity is often assumed in most image reconstruction methods, but non-linearity could exist in the relations between measured signals and blood flow variations. We have constructed a forward model for SCOT using the Rytov approximation to solve the correlation diffusion equation and compared it with the first Born approximation as well as the more accurate, but computationally expensive Monte Carlo simulation approach. We have shown that the results obtained using the Rytov approximation are in good agreement with the Monte Carlo simulations, while the first Born approximation deviates from the other two methods for large blood flow variations. For instance, the first Born approximation breaks down at around 30% cerebral blood flow (CBF) changes within a volume of size 60×50×40 mm3, therefore we recommend using the Rytov approximation above this threshold. We have shown that our defined blood flow index (BFi) measured in SCOT is linearly related to local CBF variations, thus the forward and inverse problems can be solved linearly using the sensitivity matrix approach. We have then demonstrated image reconstruction experimentally showing human brain activations using our recently developed high-density SCOS system. Our method guides experimental system design and data analysis for SCOT.

Congratulations to Tom and Kenny for publishing their latest work of characterizing cameras for SCOS measurements!

By Xiaojun Cheng June 4th, 2024

More details:

https://www.nature.com/articles/s41598-024-62106-y

Cheng, Tom Y., Byungchan Kim, Bernhard B. Zimmermann, Mitchell B. Robinson, Marco Renna, Stefan A. Carp, Maria Angela Franceschini, David A. Boas, and Xiaojun Cheng. "Choosing a camera and optimizing system parameters for speckle contrast optical spectroscopy." Scientific Reports 14, no. 1 (2024): 11915.

New publication from Bingxue Liu

By Xiaojun Cheng January 4th, 2024

Congratulations to Bingxue Liu for publishing the first paper of the Speckle group in Year 2024! This work summarizes the mathematics behind the theory of dynamic light scattering (DLS) and laser speckle contrast imaging (LSCI). It serves as a valuable resource for experimentalists to choose the correct model and for students to follow through with the details of calculations.

Dynamic light scattering and laser speckle contrast imaging of the brain: theory of the spatial and temporal statistics of speckle pattern evolution

Bingxue Liu, Dmitry Postnov, David A. Boas, and Xiaojun Cheng

Biomed. Opt. Express 15(2), 579-593 (2024) 

https://opg.optica.org/boe/fulltext.cfm?uri=boe-15-2-579https://lnkd.in/gmN8pmga

 

We are recruiting!

By Xiaojun Cheng October 26th, 2023

Title: A transformative method for functional brain imaging with speckle contrast optical spectroscopy (SCOS) and functional near infrared spectroscopy (fNIRS)
Faculty: David A. Boas (dboas@bu.edu), Xiaojun Cheng (xcheng17@bu.edu)
Description: We are looking for a PhD student to work on the project of developing a multi-channel SCOS-fNIRS optical system to achieve high quality measurements of human brain blood flow, oxygenation, and function. Please contact us if you want to rotate with us and/or want to learn more about this project.