Epidermal changes during UVB phototherapy assessed by multiphoton laser tomography

Area of Science:

• Dermatology
• Medical Imaging
• Photobiology

Background:

• Multiphoton laser tomography (MPT) offers high-resolution, non-invasive in vivo skin imaging.
• Previous studies confirmed MPT's ability to detect morphological changes from erythematogenic ultraviolet B (UVB) irradiation.
• This study explored MPT's utility in observing skin alterations during standard phototherapy using sub-erythematogenic narrow band UVB doses.

Purpose of the Study:

• To investigate if Multiphoton laser tomography (MPT) can detect morphological skin changes induced by sub-erythematogenic narrow band UVB phototherapy.
• To assess cellular damage and adaptive responses in the skin during a standard phototherapy regimen.

Main Methods:

• Sixteen patients with psoriasis vulgaris undergoing narrow band UVB phototherapy were enrolled.
• Skin measurements were taken using the DermaInspect® multiphoton tomograph at baseline, and at 1 day, 3 days, and the final day of exposure.
• A test field and a light-protected control field were analyzed.

Main Results:

• No significant changes in spongiosis or pleomorphy (indicators of inflammation and cellular damage) were observed during UVB phototherapy.
• Significant adaptive skin reactions were detected, characterized by changes in keratosis and pigmentation.
• MPT successfully visualized these photoadaptive changes.

Conclusions:

• Multiphoton laser tomography (MPT) is a valuable tool for assessing qualitative and quantitative skin changes following UVB irradiation.
• Sub-erythematogenic UVB exposure, as used in standard phototherapy, induces observable photoadaptive skin changes but not significant cellular damage detectable by MPT.