Figure 1

Slice views of the 1.5-MHz and 3.2-MHz transducer models with and without hyperplasia. Slice views transverse to the graft at the center of the 1.5-MHz transducer model (a) without hyperplasia and (b) with hyperplasia; (c) and (d) show the same slices for the 3.2-MHz transducer model. The scale is not the same for each model; the 1.5-MHz model dimensions are 2 × 2 × 4 cm, while the 3.2-MHz model is 1.5 × 1.5 × 3 cm. In both models the graft is cylindrical with a 0.6-cm inner diameter and a 0.6-mm wall thickness. The skin surface is located at the left boundary of each figure.