Non-invasive quantification of psoriasis plaques-measurement of skin thickness with 15 mHz pulsed ultrasound

The skin thickness of 31 psoriatic plaques was found to be increased (by 55% as a mean) as compared to normal appearing skin. This increase in skin thickness was correlated to habitual skin thickness, i.e. the increase was larger in normally thin skin. Consequently, plaques located to the extremities were more thickened (by 72% as a mean) as compared to plaques located on the trunk (increased by 33% as a mean). Twenty plaques measured after successful treatment with tars did not differ in thickness from normal appearing skin. Ultrasound measurements had a good reproducibility on psoriasis skin (s.d. = 0.097 mm, coefficient of variation 4.9%), Ultrasound measurement of skin thickness was shown to be suited for quantification of skin affliction with psoriasis, and for assessment of the effect of therapy. Plaques located to the extremities are preferable for such assessments.