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Spectral analysis of mechanical and respiratory influences on width of subarachnoid space assessed with non-invasive method of near-infrared transillumination/back scattering sounding

Frydrychowski A. F., Rojewski M., Gumiński W.

Opto-Electronics Review

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2002

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Vol. 10, No. 2

151-157

EN

The authors present observations on influences of hesd movements and forced respiration on the magnitudes of signals acquired with the new, non-invasive technique of near-infrared transillumination/back scattering sounding NIR-T/BSS which signals depend upon and reflect the instantaneous width of the subarachnoid space and the amplitude of its pulsation of cerebrovascular origin. For elimination of influence of the changing volume of blood in superficial vessels of skin in the frontal region, each experiment was performed twice- without and with simultaneous non-invasive exclusion of blood flow in that region through skin compression. It was observed that the recorded changes in the NIR-T/BSS signals reflecting those in the instantaneous width of the subarachnoid space and its cerebrovascular pulsation follow the time-pattern of the evoking factor, i. e. either the rhythm of the head movements or the forced respiration, which can be demonstrated on the basis of spectral analysis of the acquired transillumination signals.

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Monitoring of subarachnoid space and cerebrovascular pulsation with near-infrared transillumination/back scattering : new aspects of the method

Frydrychowski A. F., Rojewski M., Gumiński W.

Opto-Electronics Review

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2002

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Vol. 10, No. 3

175-183

EN

Authors present new aspects of recently published non-invasive method of near-infrared transillumination/back scattering (NIR-T/BS) in its application for recording of changes in instantaneous width of the subarachnoid space (SAS) , as source of information on the amplitude of cerebrovascular pulsation in subsequent phases of the cardiac cycle. For confirmation of the crebidility of the recording as carrying information on the changes within the SAS, recordings were also performed after non- invasive elimination of skin circulation in the sensor area with skin compression. It was proved that the pulsation recorded with this technique is really of intracranial origin, regardless of the blood flow in the skin of the frontal region.

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Near infrared transillumination-back scattering (NIRT-BS) : a new method for non-invasive monitoring of changes in width of subarachnoid space and magnitude of cerebrovascular pulsation

Frydrychowski A. F., Rojewski M., Gumiński W., Kaczmarek J., Juzwa W.

Opto-Electronics Review

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2001

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Vol. 9, No. 4

397-402

EN

The authors present the medical, physical, and technical background for the new method of near infrared transillumination - back scatetering. The method, for the first time ever, allows for almost complete elimination of the influence of the alterations in skin circulation on the optical signal iDS(t) subtly modulated by the changes in the width of the subarachnoid space (SAS). This has been accomplished through division of the distal or deep optical signal iDS(t) subtly modulated by the changes in the width of the subarachnoid space (SAS). This has been accomplished through division of the distal or deep optical signal iDS(t) over the optical reference signal iPS(t) which is independent of the width of SAS, but depends on the other tissue layers in the same manner as iDS(t). From the obtained quotient, a weak component was extracted that depends on the cerebrovascular pulsation. Described in this paper is the mathematical method of reducing the influence of the changes in skin blood flow on the transillumination signals. A tilt test was used as an example to show the capacity of the method to determine the cerebro-spinal reserve volume.

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Application of transillumination quotient for monitoring of the instantaneous width of the subarachnoid space

Frydrychowski A. F., Rojewski M., Gumiński W., Kaczmarek J., Juzwa W.

Opto-Electronics Review

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2001

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Vol. 9, No. 4

403-411

EN

The authors describe the application of the newly designed method of near-infrared transillumination-back scattering in monitoring of the instantaneous width of the subarachnoid space. Description is provided with the method of elimination of influence of blood circulation in the scalp on the signals recorder from individual sensors. This influence has been eliminated through application of two sensors located at different distances from the source of radiation. The quotient of the intensities of radiation received by the sensors-distal over proximal-referred to as the transillumination quotient, contains information on propagation of infrared radiation within the subarachnoid space. Mathematical background of this solution has been given. The method of near-infrared transillumination-back scattering allows for continuous non-invasive assessment of cerebrovascular pulsation through its direct effect-pulsatile changes in the width of the subarachnoid space. The authors present examples of recordings obtained in healthy volunteers.

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Verification with numeric modelling of optical measurement of changes in the width of the subarachnoid space

Pluciński J., Frydrychowski A.F.

Biocybernetics and Biomedical Engineering

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1999

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Vol. 19, no. 4

111-126

EN

Authors use numeric modelling to describe propagation of optical radiation in the tissues of the head in all directions from a single source placed on the surface of the skin. Of special interest is the propagation of radiation within the layer of cerebro-spinal fluid contained in the subarachnoid space (SAS), which is the only medium of fast-variable width and whose changes may be related with an intracranial pathology. Changes in the width of this fluid layer result in alterations in the intensity of radiation reaching a photo-detector located at a certain distance from the source. The numeric model and a specific method of numeric analysis confirmed feasibility of assessment of changes in the width of SAS with the use of optical radiation. Presented in this study are numeric simulation of propagation of radiation in the tissues of human head and results of such simulation in the function of the width of SAS. Calculations were made for different distances between the source and photo-detector and for a few selected values of bone thickness.

PL

Autorzy zastosowali modelowanie numeryczne dla opisania propagacji promieniowania świetlnego w tkankach głowy człowieka we wszystkich kierunkach od pojedynczego źródła zlokalizowanego na powierzchni skóry. Szczególnie interesujące jest rozchodzenie się promieniowania w przejrzystej warstwie o niskiej absorbancji, utworzonej przez płyn mózgowo-rdzeniowy wypełniający przestrzeń podpajęczynówkową. Ta warstwa płynowa jest jedynym wewnątrzczaszkowym ośrodkiem optycznym, którego wymiary ulegają szybkim okresowym zmianom. Ponadto, zmiany geometrii tego ośrodka mogą być powiązane i stanowią odbicie zmian chorobowych wewnątrzczaszkowych. Zmiany szerokości tej warstwy płynowej powodują zmiany natężenia promieniowania docierającego do fotodetektora zlokalizowanego w pewnej odległości od źródła. Model numeryczny oraz szczególna metoda analizy numerycznej potwierdzają możliwość oceny zmian szerokości przestrzeni podpajęczynówkowej przy użyciu promieniowania optycznego. W niniejszej pracy przedstawiono symulację numeryczną propagacji promieniowania w tkankach głowy człowieka i wyniki tej symulacji w funkcji szerokości przestrzeni podpajęczynówkowej. Obliczenia przeprowadzono dla różnych odległości detektora od źródła oraz dla kilku wybranych grubości kości czaszki.

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Near-InfraRed Transillumination (NIR- TI) a new non-invasive tool for exploration of intracranial homeostasis and monitoring of its impairments

Frydrychowski A. F., Kaczmarek J. W., Juzwa W., Rojewski M., Pluciński J., Gumiński W., Kwiatkowski C., Lass P., Bandurski T.

Biocybernetics and Biomedical Engineering

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1999

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Vol. 19, no. 2

99-108

EN

Recent research by multidisciplinary team of physiologists and experts on telecommunications and signal processing resulted in the invention of a new opto-electronic technique ofNear-InfraRed Transillumination (NIR-TI) which enables non-invasive on-line assessment of alterations in the width of the subarachnoid space (SAS). Analysis of the constant and fast-variable components of the Transillumination Quotient (cc- TQ and fvc- TQ) provides information on long-period, e.g. respiratory and positional changes in the width of SAS, and on the short-period fluctuations of that width of cardiovascular origin. The qualities of NIR- TI make it suitable for both incidental assessment of the width of the subarachnoid space (SAS) and amplitude of cerebrovascular pulsation (ACVP) as well as for prolonged monitoring of variations in these two parameters.

PL

Najnowsze badania prowadzone przez multidyscyplinarny zespół fizjologów i ekspertów w dziedzinie telekomunikacji i przetwarzania sygnałów zaowocowały opracowaniem nowej opto-elektronicznej metody transiluminacji w bliskiej podczerwieni (NIR- TI), która umożliwia bieżącą nieinwazyjną ocenę kierunku i wielkości zmian szerokości przestrzeni podpajęczynówkowej (SAS). Analiza składowych stałej i szybkozmiennej ilorazu transiluminacji (TQ) dostarcza informacji o długookresowych, tj. oddechowych i pozycyjnych zmianach szerokości SAS, a także krótkookresowych fluktuacjach szerokości SAS, zależnych od funkcji serca i naczyń krwionośnych. Zalety NIR- TI czynią tę metodę przydatną zarówno do przygodnej oceny szerokości SAS i wielkości tętnienia naczyń wewnątrzczaszkowych (ACVP), jak i do długotrwałego monitorowania zmian tych dwóch parametrów.