A CT scan combines X-ray images taken from different angles
and uses computer processing to create cross-sectional images of bones, organs,
and soft tissues inside the body. They are relatively quick and widely
available, making them a common choice in clinical settings.
A computerized tomography (CT) scan can help diagnose
Alzheimer's disease by showing structural changes in the brain, or some other critical
signs:
1.
Brain shrinkage: CT scans can show atrophy, or
shrinkage, in the brain's temporal and parietal lobes, which are important for
memory and cognitive function.
2.
Blood vessel changes: CT scans can show signs of
stroke or small vessel disease, which can be associated with vascular dementia.
3.
CT scans can also show other signs of disease,
such as infections, blood clots, brain tumors, or fluid or blood build-up in
the brain.
To help determine if someone has dementia, a doctor may
compare the size of certain brain regions to previous scans or to what would be
expected for someone of the same age and size. However, these signs are
not exclusive to dementia and can also be present in normal aging or other
neurological conditions. As a result, CT scans should be interpreted in
conjunction with other clinical information.
CT scans are the most common type of brain scan used to
diagnose dementia. They can also be useful for ruling out other conditions
that cause similar symptoms to dementia. For example, sometimes a CT scan is
used when a person isn't eligible for an MRI due to metal in their body, such
as a pacemaker.
Head CT scan: the first step in understanding
Alzheimer’s disease
Head CT scans give a detailed look inside the brain.
During a CT scan, a technologist uses special equipment to collect multiple
images of an area of the brain from different angles.
The goal of a head CT scan for Alzheimer’s disease is
twofold. First, the scan helps your doctor rule out conditions that mimic
Alzheimer’s disease. These include tumors, hemorrhages and strokes.
CT scans also help detect the loss of brain mass linked
to Alzheimer’s disease. In an affected brain, there are typically abnormal
levels of a protein called amyloid, which causes amyloid plaques to form. Along
with plaques in the brain, Alzheimer’s disease destroys important neurons,
causing the brain to shrink. Your doctor will notice shrinkage on a CT scan.
Limitations
1.
Not Diagnostic: CT scans alone cannot diagnose
Alzheimer's disease. A comprehensive evaluation typically includes a clinical
assessment, cognitive testing, and possibly other imaging techniques like MRI
or PET scans.
2.
Subtle Changes: Early stages of Alzheimer's may
not show significant changes on a CT scan, making it less useful in detecting
the disease in its initial phases.
3.
Lack of Specificity: While CT can show atrophy,
it cannot definitively diagnose Alzheimer's since atrophy can occur in various
neurological conditions.
Advances in CT Technology
·
Low-Dose CT: Newer techniques aim to reduce
radiation exposure while maintaining image quality, making CT safer for
repeated use.
·
AI Integration: Emerging technologies are
incorporating artificial intelligence to enhance image analysis, potentially
improving the detection of atrophy patterns associated with Alzheimer’s.
Conclusion
While CT technology is a valuable tool in the assessment
of Alzheimer's disease, particularly for ruling out other conditions, it is
typically used in conjunction with other diagnostic methods. A comprehensive
approach, including clinical evaluation and potentially MRI or PET scans, is
essential for an accurate diagnosis.
