Abstract
The utility and performance of optical studies of tissue depends upon the contrast and the changes of contrast in health and disease and in functional activity. The contrast is determined both by the optical properties of extrinsic chromophores and scatterers but especially upon the changes evoked by physiological activity and pathological states. Here, we have focused upon absorption changes of the intrinsic probe, blood absorbance changes due to cortical hypoxia and to haematomas, giving, for particular conditions, absorbance changes of 0.15 and over 0.4 delta OD, respectively. Functional activity may give changes of blood volume of over 0.05 delta OD with some variability due to individual responses that is best expressed as histogram displays of the distribution of response among a significant population. Responses have been observed in prefrontal parietal and occipital functions (242 tests). Extrinsic probes afford signals dependent upon the dose tolerance of the subject and can readily equal or exceed the blood volume and oxygenation signals, and currently afford vascular volume and flow indications. However, contrast agents for the functional activity of cellular function are ultimately to be expected. Finally, light-scattering changes afford osmolyte-related responses and are here shown to indicate a larger signal attributed to cortical depolarization and K+ release in hypoxia/ischaemia. Thus, the optical method affords imaging of manifold contrasts that greatly enhance its specificity and sensitivity for diagnostic procedures.
Full Text
The Full Text of this article is available as a PDF (734.8 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- BRYANT S. H., TOBIAS J. M. Changes in light scattering accompanying activity in nerve. J Cell Physiol. 1952 Oct;40(2):199–219. doi: 10.1002/jcp.1030400204. [DOI] [PubMed] [Google Scholar]
- BUTLER W. L., NORRIS K. H. The spectrophotometry of dense light-scattering material. Arch Biochem Biophys. 1960 Mar;87:31–40. doi: 10.1016/0003-9861(60)90119-3. [DOI] [PubMed] [Google Scholar]
- Chance B., Dait M. T., Zhang C., Hamaoka T., Hagerman F. Recovery from exercise-induced desaturation in the quadriceps muscles of elite competitive rowers. Am J Physiol. 1992 Mar;262(3 Pt 1):C766–C775. doi: 10.1152/ajpcell.1992.262.3.C766. [DOI] [PubMed] [Google Scholar]
- Gopinath S. P., Robertson C. S., Contant C. F., Narayan R. K., Grossman R. G., Chance B. Early detection of delayed traumatic intracranial hematomas using near-infrared spectroscopy. J Neurosurg. 1995 Sep;83(3):438–444. doi: 10.3171/jns.1995.83.3.0438. [DOI] [PubMed] [Google Scholar]
- Hill D. K., Keynes R. D. Opacity changes in stimulated nerve. J Physiol. 1949 May 15;108(3):278–281. [PMC free article] [PubMed] [Google Scholar]
- Jöbsis F. F. Noninvasive, infrared monitoring of cerebral and myocardial oxygen sufficiency and circulatory parameters. Science. 1977 Dec 23;198(4323):1264–1267. doi: 10.1126/science.929199. [DOI] [PubMed] [Google Scholar]
- KRAMER K., ELAM J. O., SAXTON G. A., ELAM W. N., Jr Influence of oxygen saturation, erythrocyte concentration and optical depth upon the red and near-infrared light transmittance of whole blood. Am J Physiol. 1951 Apr 1;165(1):229–246. doi: 10.1152/ajplegacy.1951.165.1.229. [DOI] [PubMed] [Google Scholar]
- LUBBERS D., NIESEL W. Der Kurzzeit-Spektralanalysator; ein schnellarbeitendes Spectralphotometer zur laufenden Messung von Absorptions-bzw. Extinktionsspektren. Pflugers Arch. 1959;268(4):286–295. doi: 10.1007/BF00380730. [DOI] [PubMed] [Google Scholar]
- Matcher S. J., Elwell C. E., Cooper C. E., Cope M., Delpy D. T. Performance comparison of several published tissue near-infrared spectroscopy algorithms. Anal Biochem. 1995 May 1;227(1):54–68. doi: 10.1006/abio.1995.1252. [DOI] [PubMed] [Google Scholar]
- Robertson C. S., Gopinath S. P., Chance B. A new application for near-infrared spectroscopy: detection of delayed intracranial hematomas after head injury. J Neurotrauma. 1995 Aug;12(4):591–600. doi: 10.1089/neu.1995.12.591. [DOI] [PubMed] [Google Scholar]
- Salzberg B. M., Obaid A. L., Gainer H. Large and rapid changes in light scattering accompany secretion by nerve terminals in the mammalian neurohypophysis. J Gen Physiol. 1985 Sep;86(3):395–411. doi: 10.1085/jgp.86.3.395. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Wray S., Cope M., Delpy D. T., Wyatt J. S., Reynolds E. O. Characterization of the near infrared absorption spectra of cytochrome aa3 and haemoglobin for the non-invasive monitoring of cerebral oxygenation. Biochim Biophys Acta. 1988 Mar 30;933(1):184–192. doi: 10.1016/0005-2728(88)90069-2. [DOI] [PubMed] [Google Scholar]