Biomedical Engineering Reference
In-Depth Information
12.4.4 Interventional MRI.................................................................... 269
12.5 Tissue Deformation Correction ............................................................. 269
12.6 Clinical Applications ............................................................................... 270
12.6.1 Clinical Accuracy Requirements ............................................. 272
12.6.2 Visualization .............................................................................. 272
12.7 Conclusions .............................................................................................. 273
References ............................................................................................. 274
12.1
Introduction
Just over two months after the discovery of x-rays, a bromide print was used
to aid in the surgical removal of a needle from a woman's In conven-
tional clinical practice today, the wide range of medical imaging modalities
available are largely used for diagnosis or monitoring the progression of dis-
ease. During an intervention, images showing the pathology and surrounding
anatomy may be displayed on a light box, but the correspondence between
image and patient is established entirely in the mind of the clinician, using
knowledge of anatomy and surgical appearance accrued over many years of
training. In many procedures it would be desirable if this correspondence
between image and patient could be achieved by some more accurate and
ergonomic method, providing the interventionist with aligned radiological
data showing the position of the target and surrounding critical structures.
The goal is to make procedures less invasive, faster, and safer.
Alignment of therapeutic equipment to the patient using radiological data
has long been a routine part of radiotherapy and frame-based stereotactic
neurosurgery. With the advent of 3D volume imaging techniques there has
been increasing interest in wider application of image guidance using more
flexible alignment processes and improved visualization to enhance the data
available to the interventionist. Here, rather than registering different imag-
ing modalities, the technical aim is to take preoperative images and align
them to the physical space of the patient.
The use of imaging during a procedure has created the discipline of inter-
ventional radiology. In this scenario both the target and the therapeutic
device are visible in the real-time images. Examples of this include fluoro-
scopic guidance of stent placement and ultrasound-guided breast biopsy.
Endoscopic procedures, such as laparoscopic surgery, also have the target
and the surgical tool visible in the same optical image. Though these inter-
ventions may be termed “image-guided,” there is no registration issue, and as
such we will not consider these procedures in this chapter. We are interested
in the incorporation of images taken before an intervention, which must be
aligned to the patient. Real-time imaging may have a role in this process,
however, with preoperative images enhancing the real-time view or the intra-
operative images aiding in the registration process.
hand.
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