| 41. |
- Andersson-Engels, Stefan, et al.
(författare)
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Preliminary evaluation of two fluorescence imaging methods for the detection and the delineation of basal cell carcinomas of the skin
- 2000
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Ingår i: Lasers in Surgery and Medicine. - 0196-8092. ; 26:1, s. 76-82
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Tidskriftsartikel (refereegranskat)abstract
- Abstract Background and ObjectiveFluorescence techniques can provide powerful noninvasive means for medical diagnosis, based on the detection of either endogenous or exogenous fluorophores. The fluorescence of δ-aminolevulinic acid (ALA)-induced protoporphyrin IX (PpIX) has already shown promise for the diagnosis of tumors. The aim of the study was to investigate the localization of skin tumors after the topical application of ALA, by detecting the PpIX fluorescence either in the spectral or in the time domain.Study Design/Materials and MethodsTwo fluorescence imaging systems were used to identify basal cell carcinomas of the skin in humans, after topical application of 20% ALA ointment. Both systems rely on the comparison between the exogenous and the endogenous fluorescence, performed either in the spectral domain or in the time domain. The first system works by using three images acquired through different spectral filters, whereas the second one measures the spatial map of the average fluorescence lifetime of the sample.ResultsA clear demarcation of skin malignancies was successfully performed in vivo noninvasively with both fluorescence imaging systems.ConclusionThe two complementary approaches considered in the present study show promise for skin tumor detection and delineation based on specific fluorescence features. Lasers Surg. Med. 26:76–82, 2000. © 2000 Wiley-Liss, Inc.
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| 43. |
- Andersson-Engels, Stefan, et al.
(författare)
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Tumour marking properties of different haematoporphyrins and tetrasulfonated phthalocyanine - A comparison
- 1989
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Ingår i: Lasers in Medical Science. - 0268-8921. ; 4:2, s. 115-123
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Tidskriftsartikel (refereegranskat)abstract
- Several photosensitizers were screened for their tumour-marking ability using laserinduced fluorescence in Wistar/Furth rats bearing subcutaneous adenocarcinomas inoculated in muscle. Of the studied photosensitizers, dihaematoporphyrin ether appeared to exhibit the best tumour-demarcation properties. Polyhaematoporphyrin ester and tetrasulfonated phthalocyanine were almost as good although the fluorescence yield was much lower. Monomeric haematoporphyrin also showed some tumour-marking qualities. By forming fluorescence intensity ratios, information from both the blue and the red spectral regions were used to provide the highest tumour-to-muscle contrast. Two excitation wavelengths were used, of which 337 nm rather than 405 nm excitation light seemed to yield a better tumour demarcation, due to a greater difference in the superimposing autofluorescence between tumour and surrounding tissue. The study included measurements on many inner organs in an attempt to gain a better understanding of the interaction between the drugs and various kinds of tissue.
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| 44. |
- Andersson, Mats, et al.
(författare)
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Laser spectroscopy of gas in scattering media at scales ranging from kilometers to millimeters
- 2007
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Ingår i: Laser Physics. - 1054-660X. ; 17:7, s. 893-902
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Tidskriftsartikel (refereegranskat)abstract
- Free gases are characterized by their narrow line width, and they can conveniently be studied by laser spectroscopy. The present paper discusses the monitoring of such ambient pressure gases, which are dispersed in scattering media such as aerosol-laden atmospheres, solids, or liquids. Atmospheric work basically constitutes the well-known field of differential absorption lidar (DIAL), while the study of free gas in solids and liquids was initiated more recently under the name of GASMAS (GAs in Scattering Media Absorption Spectroscopy). We discuss the connections between the two techniques, which are extensively used in our labortory. Thus, we span the field from trace-gas mapping of gases in the lower atmosphere to gas studies in construction materials, food products, and the human body. We show that the basic ideas are very similar, while the spatial and temporal scales vary greatly.
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| 45. |
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| 48. |
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| 49. |
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| 50. |
- Andersson, S., et al.
(författare)
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Tumour Localization by Means of Laser-Induced Fluorescence in Hematoporphyrin Derivative (HPD) — Bearing Tissue
- 1985
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Ingår i: Laser Spectroscopy VII : Proceedings of the Seventh International Conference, Hawaii, June 24-28, 1985 - Proceedings of the Seventh International Conference, Hawaii, June 24-28, 1985. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 9783662152539 - 9783540396642 ; , s. 401-406
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Konferensbidrag (refereegranskat)abstract
- Following systemic injection, hematoporphyrin derivative (HPD) is known to be selectively retained in malignant tissue. This property can be used in a two-fold way: a) for localizing tumours by observing the characteristic dual-peaked laser-induced fluorescence from HPD, and b) for photodynamic therapy (HPD-PDT) using a localized HPD-assisted singlet oxygen release induced by irradiation of 630 nm laser light. This rapidly developing field has recently been reviewed by DOUGHERTY.
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