Dual wavelength (532 and 633 nm) laser Doppler imaging of plaque psoriasis
School of Physics and Astronomy, The University of Manchester, Manchester, England, United Kingdom British Journal of Dermatology
(Impact Factor: 4.28).
07/2005; 152(6):1182-6. DOI: 10.1111/j.1365-2133.2005.06479.x
Increased blood flow occurs in plaques of psoriasis, and an increase in blood flow has been shown to occur in uninvolved skin adjacent to the active edge.
In order to gain more insight into the pathophysiology of the active edges of plaques of psoriasis, we investigated different components of the microcirculation in the lesional and nonlesional skin of patients with psoriasis, using dual wavelength laser Doppler imaging (LDI).
The cutaneous blood flow in 23 plaques on the forearms of 20 patients with chronic plaque psoriasis was recorded using dual wavelength LDI. Perfusion was determined within the plaque (P), in uninvolved skin adjacent to the plaque (A) and in nonadjacent skin (U).
Perfusion in plaques was increased as imaged by either 633 nm (red wavelength) or 532 nm (green wavelength) compared with both adjacent and nonadjacent uninvolved skin: median (interquartile range) P/A(RED) = 3.7 (2.5-4.9), P/A(GREEN) = 1.3 (1.2-1.6), P/U(RED) = 4.2 (2.7-6.1), P/U(GREEN) = 1.5 (1.3-1.9).
Vascular perfusion is increased within plaques of psoriasis compared with adjacent and nonadjacent uninvolved skin. The results suggest an area of increased perfusion in skin adjacent to plaques, when compared with nonadjacent skin, for both deeper (large) and superficial (small) vessels (imaged by 633 and 532 nm, respectively). We believe that this dual wavelength tool may be a suitable and useful way of assessing pathophysiology and treatment response in psoriasis.
Available from: Graham Dinsdale
- "These are areas of excessive skin growth fuelled by increased blood flow. Although previously studied with laser Doppler imaging (LDI) , DOCT would provide blood flow information at the level of individual vessels. DOCT is ideally suited to monitoring both the current status of the disease, and the effect of various treatments upon it. "
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ABSTRACT: Doppler optical coherence tomography (DOCT) combines the imaging capabilities of OCT with functional velocity imaging and is used routinely to study skin in-vivo. The skin provides a window to monitor diseases; it has been shown that changes in skin blood flow and structure are indicative of systemic disease change and representative of disease status. This study aims to aid understanding and interpretation of DOCT images of skin with respect to vessel diameter, depth and blood flow. We have constructed a tissue model using glass capillary tubes suspended at an angle of 20° to the horizontal in an Intralipid-filled tank. The Intralipid was diluted to levels which represented optimal tissue and blood flow scattering parameters. Intralipid was then pumped through the tubes to represent blood flow. The angled nature of the tubes allowed flow imaging at various depths. DOCT images were recorded using a swept-source OCT system with 1300 nm central wavelength and 6 mum axial resolution (OCMP1300SS, Thorlabs, Inc.). Data parameters extracted from images include velocity, penetration depth and their dependence on tube diameter, depth and flow. We have successfully demonstrated a tissue model that allows DOCT imaging of vessel diameter, depth and blood flow to be investigated.
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ABSTRACT: Videocapillaroscopy (VCP) can be used to explore microcirculatory modifications in skin diseases. Psoriasis shows specific capillary alterations reflecting typical histopathological changes.
To compare capillary morphology, distribution and density in psoriasis and seborrheic dermatitis of the scalp for differential diagnosis.
VCP was performed on histology-confirmed scalp lesions of 30 patients with chronic plaque psoriasis, 30 age- and sex-matched patients with seborrheic dermatitis and 30 healthy subjects. The morphology, mean density per mm(2) and mean diameter of capillary loops was measured.
Scalp psoriasis exhibited homogeneously tortuous and dilated capillaries (bushy pattern), with a 73 +/- 17 mum (mean +/- standard deviation) diameter of capillary bushes. In contrast, scalp seborrheic dermatitis presented a multiform pattern, with mildly tortuous capillary loops and isolated dilated capillaries, but a substantial preservation of local microangioarchitecture. Mean diameter of capillary bush was significantly lower (27 +/- 4 microm; p < 0.001) and similar to that of the scalp of healthy subjects (21 +/- 5 microm). Capillary loop density was similar in patients with psoriasis (23 +/- 5/mm(2)) seborrheic dermatitis (24 +/- 2/mm(2)) and healthy scalp skin (24 +/- 3/mm(2)).
VCP could be a useful noninvasive approach for differentiating between psoriasis and seborrheic dermatitis, especially when the scalp is the only affected site.
Available from: scholar.lib.vt.edu
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