Biomedical Engineering Reference
In-Depth Information
Figure 1.
Cardiac MRI images (a,b) show the original MR images with weak boundary
artifacts. (c,d) Results with the Roberts operator. See attached CD for color version.
physically motivated and model-based methods for describing region boundaries.
They are described as closed parametric curves or surfaces that deform under the
influence of internal and external forces. This term, “deformable model,” first ap-
peared in the work by Terzopoulos [6], where the generalized spline models with
continuity constraints were applied. Similar work was proposed by Grenander
et al. [7] and Miller et al. [8]. The most popular deformable model is the
snakes
model introduced by Kass et al. [2, 3]. Snake-driven approaches involve solving
the energy-based active contours minimization problem by computing geodesics
or minimal distance curves [9, 10, 11]. These approaches have been success-
fully applied to segment medical images that cannot be well segmented with other
techniques. Along with the advances of front propagation modeling methods, a
considerable number of specific modifications for various applications have been
proposed. Various terms — such as snakes, active contours, balloons, and de-
formable contours — have been used in the literature to refer to this deformable
model technique. Active contour models may incorporate a wide range of driving
forces [12, 13]. Many of them are based on minimization of combined energy
