Near-infrared light scattering and water diffusion in newborn brains.

Objective: MRI provides useful information regarding brain maturation and injury in newborn infants. However, MRI studies are generally restricted during acute phase, resulting in uncertainty around upstream clinical events responsible for subtle cerebral injuries. Time-resolved near-infrared spectroscopy non-invasively provides the reduced scattering coefficient ( ), which theoretically reflects tissue structural complexity.

Foetal growth, birth transition, enteral nutrition and brain light scattering.

If the brain structure is assessed at neonatal intensive care units, covert clinical events related with subtle brain injury might be identified. The reduced scattering coefficient of near-infrared light (μ') obtained using time-resolved near-infrared spectroscopy from the forehead of infants is associated with gestational age, body weight and Apgar scores, presumably reflecting subtle changes of the brain related to foetal growth and birth transition. One hundred twenty-eight preterm and term infants were studied to test whether μ' obtained from the head at term-equivalent age is associated with foetal growth, birth transition and nutritional status after birth, which are key independent variables of developmental outcomes.

Physiological and pathological clinical conditions and light scattering in brain.

MRI of preterm infants at term commonly reveals subtle brain lesions such as diffuse white matter injury, which are linked with later cognitive impairments. The timing and mechanism of such injury remains unclear. The reduced scattering coefficient of near-infrared light (μs') has been shown to correlate linearly with gestational age in neonates.

Hemodynamic Measurements of the Human Adult Head in Transmittance Mode by Near-Infrared Time-Resolved Spectroscopy.

Using a near-infrared time-resolved spectroscopy (TRS) system, we measured the human head in transmittance mode to obtain the optical properties and the hemodynamic changes of deep brain tissues in seven healthy adult volunteers during hyperventilation. For six out of seven volunteers, we obtained the optical signals with sufficient intensity within 10 sec. of sampling.

Measurement of maternal cerebral tissue hemoglobin on near-infrared time-resolved spectroscopy in the peripartum period.

Aim: To measure cerebral tissue hemoglobin in uncomplicated and complicated pregnant women during the peripartum period.

Methods: Time-resolved spectroscopy (TRS-20) can measure absolute concentration of oxygenated, deoxygenated, and total tissue hemoglobin based on the transit time of individual photons. Therefore, we used TRS-20 to measured tissue hemoglobin in the hemi-prefrontal lobes of normotensive pregnant women with (n = 51) or without (n = 19) epidural anesthesia, hypertensive pregnant women with pre-eclampsia (n = 10), a pregnant woman with acute onset of hypertension soon after delivery, and a hypertensive woman after hemorrhagic stroke in delivery.

Sensitivity correction for the influence of the fat layer on muscle oxygenation and estimation of fat thickness by time-resolved spectroscopy.

Near-infrared spectroscopy (NIRS) has been used for noninvasive assessment of oxygenation in living tissue. For muscle measurements by NIRS, the measurement sensitivity to muscle (S(M)) is strongly influenced by fat thickness (FT). In this study, we investigated the influence of FT and developed a correction curve for S(M) with an optode distance (3 cm) sufficiently large to probe the muscle.

Optical imaging for monitoring tumor oxygenation response after initiation of single-agent bevacizumab followed by cytotoxic chemotherapy in breast cancer patients.

Purpose: Optical imaging techniques for measuring tissue hemoglobin concentration have been recently accepted as a way to assess tumor vascularity and oxygenation. We investigated the correlation between early optical response to single-agent bevacizumab and treatment outcome.

Methods: Seven patients with advanced or metastatic breast cancer were treated with single-agent bevacizumab followed by addition of weekly paclitaxel.

Clinicopathological and prognostic impact of imaging of breast cancer angiogenesis and hypoxia using diffuse optical spectroscopy.

Near-infrared diffuse optical spectroscopy (DOS) imaging can non-invasively measure tumor hemoglobin concentration using high contrast to normal tissue, thus providing vascularity and oxygenation status. We assessed the clinical usefulness of DOS imaging in primary breast cancer. In all, 118 women with a histologically confirmed diagnosis of primary malignant tumor were enrolled.

Optical imaging of tumor vascularity associated with proliferation and glucose metabolism in early breast cancer: clinical application of total hemoglobin measurements in the breast.

Background: Near-infrared optical imaging targeting the intrinsic contrast of tissue hemoglobin has emerged as a promising approach for visualization of vascularity in cancer research. We evaluated the usefulness of diffuse optical spectroscopy using time-resolved spectroscopic (TRS) measurements for functional imaging of primary breast cancer.

Methods: Fifty-five consecutive TNM stage I/II patients with histologically proven invasive ductal carcinoma and operable breast tumors (<5 cm) who underwent TRS measurements were enrolled.

Bedside assessment of cerebral vasospasms after subarachnoid hemorrhage by near infrared time-resolved spectroscopy.

We examined the usefulness of near infrared time-resolved spectroscopy (TRS) for detection of vasospasm in subarachnoid hemorrhage (SAH). We investigated seven aneurysmal SAH patients with poor clinical conditions (WFNS grade V) who underwent endovascular coil embolization. Employing TRS, we measured the oxygen saturation (SO(2)) and baseline hemoglobin concentrations in the cortices.

Changes of evoked cerebral blood oxygenation and optical pathlength in the frontal lobe during language tasks: a study by multi-channel, time-resolved near-infrared spectroscopy and functional MRI.

To determine the alterations in optical characteristics and cerebral blood oxygenation (CBO) in the frontal lobe during language tasks, we evaluated the changes in mean optical pathlength (MOP) and CBO induced by a verbal fluency task (VFT) in the right and left frontal lobes in normal adults (n = 9, mean age = 29.6 +/- 4.8 years).

Clinical evaluation of time-resolved spectroscopy by measuring cerebral hemodynamics during cardiopulmonary bypass surgery.

We developed a three-wavelength time-resolved spectroscopy (TRS) system, which allows quantitative measurement of hemodynamics within relatively large living tissue. We clinically evaluated this TRS system by monitoring cerebral circulation during cardiopulmonary bypass surgery. Oxyhemoglobin, deoxyhemoglobin, total hemoglobin and oxygen saturation (SO(2)) were determined by TRS on the left forehead attached with an optode spacing of 4 cm.

Changes of cerebral blood oxygenation and optical pathlength during activation and deactivation in the prefrontal cortex measured by time-resolved near infrared spectroscopy.

To determine the alterations in optical characteristics and cerebral blood oxygenation (CBO) during activation and deactivation, we evaluated the changes in mean optical pathlength (MOP) and CBO induced by a verbal fluency task (VFT) and driving simulation in the right and left prefrontal cortex (PFC), employing a newly developed time-resolved near infrared spectroscopy, which allows quantitative measurements of the evoked-CBO changes by determining the MOP with a sampling time of 1 s. The results demonstrated differences in MOP in the foreheads with the subjects and wavelength; however, there was no significant difference between the right and left foreheads (p > 0.05).

Cerebral hemodynamics evaluation by near-infrared time-resolved spectroscopy: correlation with simultaneous positron emission tomography measurements.

We compared pharmacologically-perturbed hemodynamic parameters (cerebral blood volume; CBV, and flow; CBF) by acetazolamide administration in six healthy human subjects studied with positron emission tomography (PET) and near-infrared (NIR) time-resolved spectroscopy (TRS) simultaneously to investigate whether NIR-TRS could measure in vivo hemodynamics in the brain tissue quantitatively. Simultaneously with the PET measurements, TRS measurements were performed at the forehead with four different optode spacing from 2 cm to 5 cm. Total hemoglobin and oxygen saturation (SO2) measured by TRS significantly increased after administration of acetazolamide at any optode spacing in all subjects.