Quantification of cerebral blood flow in adults by contrast-enhanced near-infrared spectroscopy: Validation against MRI

Abstract

The purpose of this study was to assess the accuracy of absolute cerebral blood flow (CBF) measurements obtained by dynamic contrast-enhanced (DCE) near-infrared spectroscopy (NIRS) using indocyanine green as a perfusion contrast agent. For validation, CBF was measured independently using the MRI perfusion method arterial spin labeling (ASL). Data were acquired at two sites and under two flow conditions (normocapnia and hypercapnia). Depth sensitivity was enhanced using time-resolved detection, which was demonstrated in a separate set of experiments using a tourniquet to temporally impede scalp blood flow. A strong correlation between CBF measurements from ASL and DCE-NIRS was observed (slope = 0.99 ± 0.08, y-intercept = −1.7 ± 7.4 mL/100 g/min, and R2 = 0.88). Mean difference between the two techniques was 1.9 mL/100 g/min (95% confidence interval ranged from −15 to 19 mL/100g/min and the mean ASL CBF was 75.4 mL/100 g/min). Error analysis showed that structural information and baseline absorption coefficient were needed for optimal CBF reconstruction with DCE-NIRS. This study demonstrated that DCE-NIRS is sensitive to blood flow in the adult brain and can provide accurate CBF measurements with the appropriate modeling techniques.

Direct assessment of extracerebral signal contamination on optical measurements of cerebral blood flow, oxygenation, and metabolism

“…, whereas average thicknesses of the scalp (5 mm) and skull (7 mm) layers were obtained from a previous study. 31 It should be noted that the assumed optical properties were similar to reconstructed values presented in Sec. 3 and from previous studies.…”

“…The fitting parameters were the absorption coefficient (μ a ), the reduced scattering coefficient (μ 0 s ), and an amplitude factor. Next, the time series for each of the three moments was converted into the corresponding absorption changes Δμ a;i ðλÞ by sensitivity analysis: 31,54 E Q -T A R G E T ; t e m p : i n t r a l i n k -; e 0 0 1 ; 1 1 6 ; 2 4 2…”

“…3 and from previous studies. 31 For each subject, β was calculated as the average maximum value of the g 2 curves measured at baseline. It should be noted that no change in the β value was observed following tourniquet inflation.…”

Real-Time Non-invasive Assessment of Cerebral Hemodynamics With Diffuse Optical Spectroscopies in a Neuro Intensive Care Unit: An Observational Case Study

“…Last, the opticalderived CBF has physical units (i.e., cm 2 /s) rather than the more usual clinical units (i.e., ml/100 g of tissue/min). Some authors have proposed the use of an indocyanine-green (ICG) bolus to recover absolute CBF from the optical signal, which may be used to convert the continuous CBF index from DCS to the absolute clinical units (72)(73)(74).…”

Study protocol of validating a numerical model to assess the blood flow in the circle of Willis

“…However, MR demands that subjects are immobile for a longer period and has several contra-indications, such as metal implants. Recently, it was reported that dynamic contrast-enhanced near-infrared spectroscopy could assess CBF at the bedside, 5 which compensates for the disadvantages of MR, but this technique still needs to be validated.…”