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Abstract Back pain resulting from degenerative disease of the
spine is one of the most common causes of disability in working-
age adults. Between 60% to 80% of adults suffer from low-back
pain at some time in their life. Spondylolisthesis is reported
recently in 4 percent of the general adult population, and in
more than 2 percent of asymptomatic patients. Many diseases,
such as decrease in the height of the intervertebral disc,
degenerative changes in the facet joints and hypertrophic
changes of the ligamentum flavum or protrusion of the annulus
fibrosus, resulted in narrowing of one or both neural foramena.
Total of seventeen subjects were included, six subjects with a
diagnosis of degenerative spondylolisthesis and eleven subjects
with a diagnosis of induced spondylolisthesis. The fourth and
fifth lumbar (L4-L5) was the portion on vertebrae studied in
this research. Computer tomography (CT) has good resolution on
bone, so does MRI on soft tissue. In discussing the relationship
between the neural foramen and neural root, MRI has become the
modality of choice in the evaluation of the spinal degenerative
disease. The only major disadvantage is lack of the bone detail.
To improve the diagnosis performance of the image, we used CT
image of the bone to replace and enhance the image in MRI. The
reference points (the external landmarks) were applied to fusion
CT and MRI image, and then to deal with image by way of the
rotation and translation matrix. The better image (Voxel data)
was obtained after linear interpolation and scaling at image
processing. We reconstructed the sagittal plane image and
measured the dimension of the neural foramen, neural root and
intervertebral disc.The fusion image shows the better result of
the neural foramen and neural root. The external landmarks
become the reference points that can provide locations for
fusion image. MRI has a good soft tissue resolution, the
reconstruction of the sagittal plane image had blurred image
after image processing. Although we are unable to get the best
reconstruction MRI image, but the fusion image could improve the
defects of CT image. No statistical significances (p>0.05) were
found at a both sides of the induced spondylolisthesis, but
significant differences (p<0.05) at a both sides of the
degenerative spondylolisthesis. A seriously degeneration
happened sometimes at single side which decreased the heights of
the intervertebral disc. These changes might influence the
dimensions of the intervertebral foramina. The variation of the
cross-sectional areas of the nerve roots was not statistically
significant (p>0.05), but is significant (p<0.05) for that of
the foramina in the induced and degenerative spondylolisthesis.
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