New aspects in assessment of changes in width of subarachnoid space with near-infrared transillumination-backscattering sounding, part 2: clinical verification in the patient.

The study presents comparison of near-infrared light propagation and near-infrared backscattered radiation power, as simulated with numerical modeling and measured live in a patient in clinical conditions with the use of the near-infrared transillumination-backscattering sounding (NIR-TBSS) technique. A unique chance for such precise comparative analysis was available to us in a clinical case of a female patient with scalp removed from one half of the head due to injury. The analysis performed indicates that the difference between the intensity of the signals in numerical modeling and live measurements is less than 4 dB. Analysis of the theoretical model also provides hints on the positioning of the two detectors relative to the source of radiation. Correctness of these predicted values is confirmed in practical application, when changes of signals received by the detectors are recorded, along with changes of the width of the subarachnoid space. What is more, the power distribution of the spectrum of near-infrared backscattered radiation returning to the detectors is confirmed in the real recording in the patient. An abridged description of the new method of NIR-TBSS is presented.