Biomedical Engineering Reference
In-Depth Information
13.3.1
Intrasubject Registration
The goal of intrasubject registration is the matching and fusion of images of
the same subject acquired at different times and
or with different imaging
modalities. The need for nonrigid registration arises from the fact that most
tissues are far from rigid and can deform considerably. This tissue deforma-
tion may be caused by patient motion, cardiac motion, or respiratory
motion. For example, nonrigid registration plays an important role for con-
trast enhanced MR imaging of the breast. Here, the difference between the
rate of uptake of contrast agent in healthy and cancerous tissue can be used
to identify cancerous lesions. The rate of uptake of contrast agent is esti-
mated as the difference between pre- and postcontrast images, and any
motion between both images complicates its estimation. Due to the highly
deformable nature of the breast tissue, Rueckert et al.
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have developed a
nonrigid registration technique to correct for this motion. An example of
this is shown in Figures 13.3 and 13.4. A clinical evaluation in comparison
FIGURE 13.3
A contrast-enhanced MR mammography: (a) precontrast, (b) postcontrast and after subtrac-
tion (c) without registration, and (d) with nonrigid registration.
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