Conventional ultrasonography and sonoelastography in the assessment of plaque psoriasis under topical corticosteroid treatment - work in progress.

AIMS: The objective of the study was to compare the efficiency of 20 MHz skin ultrasonography and 40 MHz conventional ultrasonography in the assessment of plaque psoriasis and to assess the efficiency of 40 MHz real-time sonoelastography in the early detection of steroid-induced skin atrophy in psoriatic plaques. PATIENTS AND METHODS: Ultrasonographic blinded evaluation was performed on 16 plaques in three consecutive patients, at baseline and after hydrocortisone acetate 1% ointment six-week application. The parameters were epidermal and dermal thicknesses for gray-scale ultrasonography and strain ratio for sonoelastography. Strain ratio was computed between the dermis and the adjacent hypodermis. Student's t-test for paired samples was performed. A confidence level of p<.05 was considered significant.
RESULTS: At follow-up, epidermal thickness was significantly reduced with 20 MHz (p = .002) and 40 MHz sonography (p = .032), while dermal thickness varied insignifcantly with 20 MHz (p = .35) and 40 MHz sonography (p = .33). Measurements at 40 MHz were significantly higher than their 20 MHz counterparts at baseline (epidermis: p < .001; dermis: p = .003) and at follow-up (epidermis: p < .001; dermis: p = .001). Strain ratio revealed no significant change of dermal elasticity (p = .96).
CONCLUSIONS: Although epidermal and dermal measurements varied significantly with 20 MHz and 40 MHz ultrasonography, both techniques efficiently quantified treatment response by measuring the reduction of epidermal thickness. Sonoelastographic findings were consistent with the expected outcome of short-term use of low-potency corticosteroid. Further studies are recommended.