Diffuse correlation spectroscopy: current status and future outlook

Abstract

. 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 variety of approaches to improve measurement performance and reduce cost are being explored; these include interferometric methods, camera-based multispeckle detection, and long path photon selection for improved depth sensitivity. We review here the current status of DCS technology and summarize future development directions and the challenges that remain on the path to widespread adoption.

Advances in Dynamic Light Scattering Imaging of Blood Flow

“…[26][27][28]31,93] Thus, extended for use in turbid dynamic media, such as biological tissues, where a diffusive regime of light scattering is assumed, DLS, known as DWS and/or DSC (see Figure 2a), applied extensively for blood flow diagnosis. [34,37,38]…”

“…Subsequent developments of the DWS approach employing near-infrared light for non-invasive measurement, with a focus on directly measuring local microvascular cerebral blood flow (CBF), are also collectively known as diffuse correlation spectroscopy (DCS). [37,38] Among the DLS, LDF, and DWS, there is also a full-field method known as speckle imaging or laser speckle contrast imaging (LSCI). [39,40] Introduced in 1981 [39] the LSCI utilizes a coherent laser source (e.g., a laser diode) for illumination of object of interest and a digital camera (CCD or CMOS) for raw speckle image acquisition and is extensively used in various pre-clinical examinations for monitoring of blood microcirculation in the superficial layers of biological tissues, for example, for screening blood flow in tumors.…”

Special Section Guest Editorial: Thirty Years of Functional Near-Infrared Spectroscopy

“…A range of optical techniques have been used for fNIRS, including continuous wave, frequency domain, time domain, and broadband spectroscopy. Recent advances also allow measuring cerebral blood flow using diffuse correlation spectroscopy and interferometric techniques 8 , 9 . Interferometric techniques offer some hardware advantages over diffuse correlation spectroscopy, and both have progressed to multichannel systems that can reconstruct brain blood flow maps.…”

Using depth-enhanced diffuse correlation spectroscopy and near-infrared spectroscopy to isolate cerebral hemodynamics during transient hypotension

“… – 23 More advanced technologies, i.e., time-resolved and frequency-domain methods, have proven effective for enhancing the depth sensitivity of NIRS 24 – 27 Time-resolved detection has also been applied to DCS 28 ; however, this approach is challenging due to the poorer signal-to-noise ratio of current DCS technology 29 . Consequently, multi-distance continuous-wave DCS remains the most commonly used approach in neuromonitoring applications.…”