Thickness measurements of melanocytic skin lesions: method comparison between histology and high-frequency ultrasound using 20MHz and 100MHz ultrasound transducers

Problemstellung: The aim of this pilot study was to evaluate the accuracy of 100MHz-ultrasound (US) for the determination of mean vertical tumor thickness (TT) of melanocytic nevi (MN), compared with 20MHz-US and histological findings, by applying appropriate statistical methods. Patienten und Methode: In this prospective study 21 patients with pigmented skin tumors were referred to the Department of Dermatology, Ruhr-University Bochum (Germany) for further evaluation and management. The study was conducted in the light of the declaration of Helsinki. All patients who participated in the investigation signed an informed consent. After clinical inspection and dermoscopic evaluation, the patients' skin lesions were subjected to 100MHz-US and 20MHz- US measurements. Following excisional biopsy, the relationship between sonometric and histologic findings was established. Ergebnisse: The 21 patients had in total 37 MN. TT measurements, demonstrated a significant (P<0.0001) correlation between histology and highfrequent-US as expressed in r values of 0.99, both for 20MHz-US and 100MHz-US. Repeatability coefficient was similar for the three methods. Mountain plot demonstrated that both 20MHz-US and 100MHz-US resulted in bias which was greater for 20MHz-US. Bland and Altman plots bias (14.7 um), confirmed that 20MHz-US usually generates considerably greater values for TT than histology. By comparison, histology vs. 100MHz-US showed a smaller bias of 10 um and more narrow 95% limits of agreement (1.8 um to 15.8 um). Schlussfolgerungen: Due to its higher resolution 100MHz-US may be a more accurate tool in TT assessment than conventional 20MHz. A large scale study is now warranted to investigate TT by means of 100MHz. Picture of a naevus with 100MHZ Ultrasound.