HISTORY OF HIGH-FREQUENCY SONOGRAPHY

The development of high frequency sonography (<20MHz) has gained incre asing importance since the last decade. In this field A-mode-scanner w ere used firstly in the measurement of skin thickness. 1987 the first commercial available 20 MHz B-scanning system was introduced. These sy stems provided the possibility of correlating the ultrasound images wi th the micromorphological findings in histology. With these correlatio ns we were able to interpret ultrasound phenomena and in conclusion we were able to measure tumour thicknesses with direct impact on the the rapeutic regimen. In inflammatory skin diseases the role of high frequ ency ultrasound in follow up investigations of morphea and systemic sc lerosis must be underlined. We believe that in this field the techniqu e is the ''golden standard''. In other inflammatory diseases (e.g. pso riasis) or wound healing ultrasound is mainly used for scientific purp oses. The investigation of intraepidermal structures and differential diagnosis is only possible with higher frequencies than 20 MHz. Theref ore we developed 50 and 100 MHz in vivo scanning systems. With resolut ion up to 11 mu m (100 MHz) we hope to answer open questions in the fu ture. Ultrasound microscopy is widely used for scientific evaluation o f tissue morphology in vitro (resolution < 1 mu m). Computer-based thr ee-dimensional reconstructions provide additional information (e.g. tu mour volume or tumour surface). These parameters are well suited to fo llow up the effect of systemic or local therapies on skin metastases o f different cancers. However, also the tumour volume of the primary tu mour (in vivo) might be of great interest as a prognostic parameter in future. Image analysis is important for the quantification (and diffe rential diagnosis) of ultrasound images; however this is at present in a very early stage and should not be overrated.