[Front cover]

The front cover shows results of measurements with a high frequency ultrasound based strain imaging system. A stepwise decreased pressure was applied to the skin surface in order to cause suction. Consecutive frames of radio frequency echo signals were acquired after each pressure change utilizing ultrasound in the 20 MHz range. The presented B-mode image is the envelope of the first acquired frame of echo signals. A hypoechoic nevus inside the hyperechoic dermis and the subjacent subcutaneous fat are visible. Furthermore, the segmented skin surface contours, which were segmented in each signal frame, are shown. Axial displacements between echo signals in consecutive frames were estimated applying a phase sensitive correlation approach, and axial strains were calculated as the spatial derivative of estimated displacements. The color coded strain image shows that large elongational strains occur in the subcutaneous fat, whereas compressional strains are given in the nevus. Images courtesy of Michael Vogt and Helmut Ermert, Institute of High Frequency Engineering, Dept. of Electrical Engineering and Information Technology, Ruhr-University, Bochum, Germany. See article on page 375.