Biomedical Engineering Reference
In-Depth Information
6.5
Chapter 6.5
Registration for image-guided
surgery
Eric Grimsom and Ron Kikinis
6.5.1 Introduction
Shorter procedures through increased visualization
of the surgical field.
Reduced risk of sensitive tissue damage.
More accurate and complete tissue resection,
ablation, or biopsy.
The key stages of an accurate, reliable, image-guided
surgery system are as follows:
Creating accurate, detailed, patient-specific models
of relevant anatomy for the surgical procedure.
Registering the models, and the corresponding
imagery, to the patient.
Maintaining the registration throughout the surgical
procedure.
Tracking medical instruments in the surgical field
in order to visualize them in the context of the
MR/CT imagery and the reconstructed models.
In this chapter, we describe the registration process used
to align preoperative imagery with the actual patient
position, and the process by which a surgeon visualizes
and navigates through the patient using that information.
We do this using an example of a neurosurgical image-
guidance system, although the same issues arise in other
areas as well.
Many surgical procedures require highly precise locali-
zation, often of deeply buried structures, in order for the
surgeon to extract targeted tissue with minimal damage
to nearby structures. Although methods such as MRI and
CT are invaluable in imaging and displaying the internal
3D structure of the body, the surgeon still faces a key
problem in applying that information to the actual pro-
cedure. Since he is limited to seeing exposed surfaces
within the surgical opening, he cannot easily visualize
paths to targets or positions of nearby, but hidden, critical
structures. In addition, the lack of visible landmarks
within the surgical opening may inhibit his ability to
determine his current position, and thus to navigate safe
trajectories to other structures.
Because traditional clinical practice often only utilizes
2D slices of MR or CT imagery, the surgeon must men-
tally transform critical image information to the actual
patient. Thus, there is a need for techniques to register
a 3D reconstruction of internal anatomy with the surgical
field. Such registered information would support image-
guided surgery, by allowing the surgeon to directly visu-
alize important structures, and plan and act accordingly.
Visualization methods include ''enhanced reality visuali-
zation''
[14]
, in which rendered internal structures are
overlaid on the surgeon's field-of-view, and instrument
tracking, in which medical instruments acting on the
patient are localized and visualized in the 3D MR or CT
imagery. The benefits of image-guided surgical methods
include the following:
Accelerated migration to minimally invasive
surgeries via improved hand-eye coordination and
better transfer of a
priori
plans to the patient.
6.5.2 Image-guided neurosurgery
system
Neurosurgery is an ideal application for image-guided
techniques, by virtue of the high precision it requires,
the need to visualize nearby tissue, the need for planning
of optimal trajectories to target tissue, and the need
to localize visually indistinguishable, but functionally
