SSMs of Breast Ultrasound Images
Few studies have focused on SSMs of breast ultrasound images, because of the paucity of landmarks, the deformability of the tissue, and operator dependence. To overcome such problems, several automated whole breast ultrasound scanners have been developed [275, 307]. Figure 3.60 shows an example of a volumetric whole breast image, where a 16 x 16 cm2 area is scanned automatically. It is assumed that whole breast scanning techniques will enable the construction of an SSM for the
Fig. 3.59 The B-mode (a) and Nakagami (b) images of a benign breast tumor 
Fig. 3.60 An example of volumetric whole breast image (a) volumetric data in a 16 x 16 cm2 area. (b) A whole breast section view 
Fig. 3.61 Bilateral breast images are registered with reference to the nipple positions and skin lines. (a) Fusion image before registration. (b) Fusion image after registration 
purpose of assessing symmetry, looking at lesions over time, and fusing ultrasound images with mammograms and MR images.
Ikedo et al.  have reported bilateral breast comparison and registration methods for reduction of false positives in a detection system for masses. Normal left and right breasts in the same subject are usually architecturally symmetrical. A mass-like area in a region is classified as normal tissue if the same position in the other breast has a similar feature. Example sections after implementation of the registration are shown in Fig. 3.61.