Non-invasive optical imaging of stroke

Abstract

The acute onset of a neurological deficit is the key clinical feature of stroke. In most cases, however, pathophysiological changes in the cerebral vasculature precede the event, often by many years. Persisting neurological deficits may also require long-term rehabilitation. Hence, stroke may be considered a chronic disease, and diagnostic and therapeutic efforts must include identification of specific risk factors, and the monitoring of and interventions in the acute and subacute stages, and should aim at a pathophysiologically based approach to optimize the rehabilitative effort. Non-invasive optical techniques have been experimentally used in all three stages of the disease and may complement the established diagnostic and monitoring tools. Here, we provide an overview of studies using the methodology in the context of stroke, and we sketch perspectives of how they may be integrated into the assessment of the highly dynamic pathophysiological processes during the acute and subacute stages of the disease and also during rehabilitation and (secondary) prevention of stroke.

Modified Beer-Lambert law for blood flow

“…Diffuse optical techniques, such as near-infrared or diffuse optical spectroscopy (DOS, NIRS) and diffuse correlation spectroscopy (DCS), have been employed with remarkable success over the last two decades to probe hemodynamic processes in highly scattering tissues such as human brain, muscle and breast [1][2][3][4][5][6][7][8][9][10][11]. In total, this research has discovered new indicators of tissue function and health that are proving to be clinically relevant [6][7][8][9][10][11][12][13][14].…”

“…In total, this research has discovered new indicators of tissue function and health that are proving to be clinically relevant [6][7][8][9][10][11][12][13][14]. The most basic DOS/NIRS instrument measures diffuse reflectance from tissue as a function of input wavelength, and thereby derives the concentration of tissue chromophores and contrast agents, including oxyand deoxy-hemoglobin (HbO 2 , Hb), and changes thereof.…”

Neurotoxic effects of indocyanine green -cerebellar granule cell culture viability study

“…These two contrast based techniques may provide complementary information on structure of the lesion (MRI) and temporal fluctuation of perfusion in the area with limited blood flow. The possible application of ICG in brain ischeamia monitoring was recently presented by Obrig et al [29,30].…”

Assessment of a multi-layered diffuse correlation spectroscopy method for monitoring cerebral blood flow in adults

“…Near-infrared spectroscopy (NIRS) is a portable, non-invasive technology that can be used to monitor cerebral oxygenation at the bedside of critical-care patients [9,10]. Cerebral blood flow can be measured directly using the optical dye indocyanine green as an intravascular contrast agent [11][12][13].…”