[Progress in NIRS monitoring of cerebral blood flow].

Various studies have demonstrated the usefulness of near infrared spectroscopy (NIRS) for detecting cerebral ischemia during a carotid endarterectomy; however, it is difficult to apply NIRS to the diagnosis of ischemic stroke, since commercially available NIRS, which uses continuous-wave light, does not provide quantitative values of baseline hemoglobin (Hb) concentrations. In contrast, time-resolved near-infrared spectroscopy (TRS) permits quantitative measurement of Hb concentrations. We applied TRS to detection of cerebra vasospasm after subarachnoid hemorrhage (SAH).

[Case of skull metastasis from hepatocellular carcinoma at the site of skull fracture].

It has occasionally been reported that mechanical trauma and posttraumatic inflammation may promote metastasis from a primary tumor to the site of the trauma. However, the etiologies that contribute to the metastasis formation at the trauma site remain unknown. We describe here the first case of skull metastasis from hepatocellular carcinoma (HCC) revealing a growing subcutaneous mass at the site of skull fracture.

Theoretical and experimental investigation of the influence of frontal sinus on the sensitivity of the NIRS signal in the adult head.

The sensitivity of the near-infrared spectroscopy signal to the brain activation depends on the thickness and structure of the superficial tissues. The influence of the frontal sinus, which is void region in the skull, on the sensitivity to the brain activation is investigated by the time-resolved experiments and the theoretical modelling of the light propagation in the head. In the time-resolved experiments, the mean-time of flight for the forehead scarcely depends upon the existence of the frontal sinus when probe spacing was shorter than 30 mm.

Mapping of optical pathlength of human adult head at multi-wavelengths in near infrared spectroscopy.

Measurement of multichannel continuous-wave near-infrared spectroscopy (CW-NIRS) is dependent on the modified Beer-Lambert law, which includes optical pathlength (PL) as an essential parameter. PLs are known to differ across different head regions and different individuals, but the distribution of PLs for the whole head has not been evaluated so far. Thus, using time-resolved near-infrared spectroscopy (TR-NIRS), we measured the optical characteristics including PL, scattering coefficients (mu'(s)), and absorption coefficients (mu(a)) at three wavelengths (760, 800, 830 nm).