Biomedical Engineering Reference
In-Depth Information
Integration of anatomical and functional images began to emerge during the
late 1980s using software-based registration techniques [117, 118], although it
was pointed out much earlier by Wagner [119] that this would be the trend for
clinical imaging. These software-based registration techniques are applied to
register images obtained with different imaging modalities or tracers (in case
of registering emission tomographic images), of the same subject at different
times. Registration techniques are successful for a rigid organ, such as the brain
but they have been found to be problematic for other parts of the body.
Recognizing the advantages of combining the information provided by ana-
tomic imaging and functional imaging, a prototype of an integrated scanner for
PET and CT was designed in the early 1990s and a commercial hybrid scanner,
named “PET/CT,” has been developed recently [120]. PET/CT is a completely
new imaging technique that will likely revolutionize the conventional habit of
acquiring and reading PET and CT data separately in the clinical environment.
PET/CT imaging will enhance the combined utilization rate of what used to
be PET-only or CT-only imaging as it provides, simultaneously, co-registered
(fusion) images of both functional and anatomical information in a single acqui-
sition. A potential advantage is the use of CT images for attenuation correction of
PET emission data, thereby the need for acquiring a separate, lengthy transmis-
sion scan can be completely eliminated. Figure 2.13 shows a combined PET/CT
Figure 2.13:
(Color slide) Combined PET/CT scan on a 72-year-old woman with
a primary pancreatic cancer. From left to right: FDG-PET image, CT image, and
fused PET and CT images. The scan shows abnormal FDG uptake in the pancreas
(arrow). The fused image shows good alignment of two modalities and enables
uptake to be localized to pancreas (arrow).
