The use of high-frequency ultrasound as a method of assessing the severity of a plaque of psoriasis

Background and Design: Ultrasound imaging, while initially developed to visualize internal organs, is now being applied to image the skin. In this preliminary study, we used a high-frequency, 40-MHz ultrasound imaging system to provide high-resolution images in psoriasis and examined the relationship between clinical and ultrasound ratings in plaque-type psoriasis. The ultrasound image of a psoriatic plaque demonstrates a superficial echogenic band (band A), followed by a nonchogenic band (band B), and a deeper echogenic band (band C). Results: In psoriatic plaques (N=145), the severity of the psoriasis as assessed according to the degree of scaling, erythema, and thickness (SET score) correlated best with the width of band B (P<.001, r=0.86) and less well with the width of bands A (P<.001, r=0.59) and C (P<.001, r=0.44). For the treated psoriatic plaques (n=64), for which paired readings were available before and after therapy, changes in the SET scores correlated best with the change in the width of band B (P<.001, r=0.96) and less well with the change in the width of bands A (P<.001, r=0.61) and C (P<.001, r=0.45). Ultrasound analyses and clinical evaluation were performed by independent raters. Conclusions: The data suggest that high-frequency ultrasound imaging may prove to be a noninvasive technique that can be used as an adjunct to the clinical evaluation of the lesional severity of psoriatic plaques.