RSOM assessment of vasodilation.

Analysis of skin morphology and microvasculature is of paramount interest in dermatology. The ability to non-invasively monitor changes in these endpoints, particularly after a stimulus such as heating or pharmacological treatment, may reveal dysfunction or therapeutic responses.

Schematic of RSOM system and experimental protocol

(a) Custom-built handheld RSOM system featuring a precise temperature control system for focal heating. The ultrasound transducer (1) and fiber bundles (2) are raster-scanned together over the ROI on the skin surface. The interface unit (3) contains coupling medium and is in direct contact with the forearm (4). Water (5) in a thermostated bath (6) is pumped (7) via silicon tubes (8) through the interface unit.
(b) Schematic of the timing of RSOM measurements during rapid heating experiments. The red line indicates a water temperature of 44 °C in direct contact with the skin surface.
(c) Schematic of the timing of RSOM measurements during gradual heating experiment

Imaging of a healthy volunteer

The forearm of a healthy volunteer was imaged before and after heating at 44 °C.
(a-d) Sagittal views of the dorsal aspect of the forearm before and after heating. In panel (a), horizontal lines demarcate the epidermis (1) and dermis (2).
(e-h) Sagittal views of the volar aspect of the forearm before and after heating.
(i-j) Sagittal view of the dorsal aspect of the forearm showing the dilation of a single vessel (boxed) before and after heating. Inset, close-up view of the vessel, with the vertical line indicating the cross-section displayed in panel (k)
(k) Amplitude profile of the vessel in panels (i) and (j), before (blue) and after (red) heating
Scale bars, 500 μm.

Quantification of heat-induced vasodilation

(a-b) The volar and dorsal aspects of the forearms of six healthy volunteers were imaged using RSOM before and after heating at 44 °C. Partial blood volume was measured in dermis of the (a) volar aspect and (b) dorsal aspect.
(c) Blood vessel diameter was measured in 12 arbitrarily selected vessels in the dermal upper plexus of the volar forearm of multiple volunteers. Solid black lines connect diameters of the same vessel before and after heating.
(d) Partial blood volume was measured in dermis while the temperature of the coupling medium at the skin surface of three volunteers was gradually heated from 25 °C to 44 °C over 9 min. p values indicate the differences between selected samples.

Berezhnoi A et al., Assessing hyperthermia-induced vasodilation in human skin in vivo using optoacoustic mesoscopy, J Biophotonics. 2018 Mar 23:e201700359. DOI: 10.1002/jbio.201700359.

  • Berezhnoi A et al.,
    Assessing hyperthermia-induced vasodilation in human skin in vivo using optoacoustic mesoscopy,
    J Biophotonics. 2018 Mar 23:e201700359. DOI: 10.1002/jbio.201700359.
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