ULTRASOUND STRUCTURE AND DIGITAL IMAGE-ANALYSIS OF THE SUBEPIDERMAL LOW ECHOGENIC BAND IN AGED HUMAN SKIN - DIURNAL CHANGES AND INTERINDIVIDUAL VARIABILITY

Subepidermal low-echogenic band is a consistent echostructural finding in aged and photodamaged skin. The thickness of subepidermal low-echo genic band is considered to closely reflect the degree of cutaneous ag ing and its use for the monitoring of the severity of photoaging and t he efficacy of drugs is rapidly expanding. We investigated subepiderma l low-echogenic band structure in 23 old healthy volunteers (ages 75-1 00) with a high-frequency ultrasound scanner (B-mode, 20 MHz). Images were collected from the volar forearm twice daily: in the morning befo re getting up and 12 h later. To assess the severity of subepidermal l ow-echogenic band, echogenicity of the subepidermal region was determi ned by the image analysis and compared with visual scoring and subepid ermal low-echogenic band thickness. All three methods gave consistent results, image analysis being the most sensitive, reliable, and bias-f ree. Significant interindividual variability of subepidermal low-echog enic band echostructure was revealed. Moreover, circadian variability of subepidermal low-echogenic band echogenicity was observed. These ma jor interindividual and diurnal variations of subepidermal low-echogen ic band suggest that this band does not only represent an irreversible structural change but also a redistribution of fluid in the aged derm is. Diurnal variations in the subepidermal low-echogenic band would li mit the use of this parameter in studies of skin aging, photoaging, an d efficiency of medication.