Sensitivity of near-infrared spectroscopy and diffuse correlation spectroscopy to brain hemodynamics: simulations and experimental findings during hypercapnia

• DOI: 10.1117/1.nph.1.1.015005
• Publication Date: 2014-08-07T19:31:46Z
• Authors: Juliette Selb; David A. Boas; Suk-Tak Chan; Karleyton C. Evans; Erin M. Buckley; Stefan A. Carp
• Keywords: Deoxygenated Hemoglobin; Haemodynamic response

Near-infrared spectroscopy (NIRS) and diffuse correlation (DCS) are two optical technologies for brain imaging that sensitive to changes in hemoglobin concentrations blood flow, respectively. Measurements both modalities acquired on the scalp, therefore hemodynamic processes extracerebral vasculature confound interpretation of cortical signals. The sensitivity NIRS versus tissue contrast-to-noise ratio (CNR) cerebral responses have been well characterized, but same has not evaluated DCS. This is important assess order understand their relative capabilities measuring physiological changes. We present Monte Carlo simulations a head model demonstrate brain-to-scalp about three times higher DCS (0.3 at 3 cm) than (0.1 cm). However, because levels noise due photon-counting detection, CNR similar response physiologically realistic simulation activation. Even so, we also observed during graded hypercapnia adult subjects with NIRS.