Biomedical Engineering Reference
In-Depth Information
FIGURE 11.1
An early example of coregistration of anatomical and functional data in nuclear medicine.
The scan shows the intracerebral ventricular system after an intrathecal injection of
131
I-HSA
superimposed on a lateral skull x-ray. Both imaging systems produced life-size images,
making alignment relatively straightforward. (Image courtesy of Professor Henry N. Wagner,
Jr., Johns Hopkins School of Hygiene and Public Health, Baltimore).
99m
Kuhl et al. reported using a chest x-ray and a [ ]-sulphur colloid liver
scan to detect pleural effusions. By overlaying the gamma camera image with
the x-ray and drawing the boundaries of the diaphragm they could identify
the fluid collections.
Tc
2
Similarly, Anger and McRae used chest x-rays in con-
junction with liver and lung scans to demonstrate discrepancies which would
indicate a subphrenic collection between the liver and the diaphragm. They
also detected pericardial effusions by overlaying a gamma camera transmis-
sion image (analogous to a low resolution x-ray) on the nuclear medicine
blood pool image.
3,4
These are some of the earliest uses of image registration
as a complement to the conventional nuclear medicine scan. An example is
shown in Figure 11.1. From the late 1960s, nuclear medicine devices have had
the ability to measure transmission as well as the emission distribution of the
radiotracer.
5-10
This is now standard, with sophisticated transmission systems
using scanning line sources
11
12,13
available on most
gamma cameras. More recently, dedicated purpose-built dual imaging
devices incorporating x-ray CT with either PET or SPECT detectors in a single
scanner have been developed and will be discussed later.
or stationary sources
14,15
11.3
Spatial Registration of Nuclear Medicine Images
Possibly the best known application of image registration in nuclear med-
icine today is that of spatially coregistering nuclear medicine emission
scans with other radionuclide scans or with anatomical images. This can
