Sonography of the skin and subcutaneous tissues.

Recent developments in US instrumentation, in particular the advent of 20-MHz transducers, have made B-mode US imaging of the skin feasible. Various pathologic conditions of the skin, mainly tumors and inflammatory diseases, can now be visualized, measured and monitored. The widely available 7.5- and 10-MHz transducers are adequate for the examination of subcutaneous tissues. The knowledge of the normal anatomy of skin and subcutaneous tissues helps diagnose such pathologic conditions as epidermoid and sebaceous cysts, benign and malignant tumors (nevi, hemangiomas, dermatofibromas, melanomas, lipomas, angiomas and angiosarcomas), inflammatory processes (inflammatory dermatoses, panniculites), traumas and foreign bodies. US was also used to measure subcutaneous fat thickness, especially in malnutrition, diabetes mellitus and acromegaly or in the patients treated with pentoine. Finally, US was employed to guide the needle into the veins of the patients with diffuse edema. Thanks to its excellent spatial resolution and cost-effectiveness, high-resolution US is expected to be used more extensively in the evaluation of skin and subcutaneous tissues.