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Alzheimer's Disease is a condition marked by memory decline. Brain imaging studies have become more valuable in the diagnosis of this disease in recent decades and all come with a set of advantages and disadvantages during the course of a medical work-up.

When it comes to Alzheimer's Disease, there are a number of factors and symptoms that can help guide a doctor towards a diagnosis of this condition. As we have seen when investigating how Alzheimer's Disease affects your brain, there will be physiological changes to the structure of the brain that may not be evident at the start through a simple history and physical examination. At this point, the most important tool in the diagnosis could be the use of brain imaging studies. Here, I will explain some of the basic facts to know about each of the important brain imaging studies and what types of findings you will see with these investigations in patients with Alzheimer's Disease. 

The MRI: How can it be used in the diagnosis of Alzheimer's?

As medicine has improved in the last few decades, the role of these brain imaging studies has become more and more important in the diagnosis of the Alzheimer's Disease. One of the key studies is known as Magnetic resonance imaging; the MRI. In laymen's terms, this is an imaging study that relies on a magnetic field in order to get a good view of your internal organs. The magnetic field can actually influence the water molecules that are naturally found in your body in order to give a very refined picture of what is going on in your body. It is best to use this type of imaging for soft tissue; the exact type of tissue that you will be looking at when you are investigating the brain. 

This can be a rather long examination for patients to endure and patients will need to lie as still as possible in order to get an accurate picture of the structures being investigated. During just a simple head investigation, patients may be asked to lie still for at least 30 minutes. This may sound like a simple task but the tubing in the room is rather small so many patients may not enjoy the slight claustrophobia that may occur. It is one of the best studies to do though so it is worth the slight discomfort for the patient. 

Once you actually finish with this examination, doctors will be able to determine whether there is atrophy or not on the base of the brain. This is a fancy medical term used to describe the death of tissue.

In this case, it will be neurons and axons that work in the brain to send signals between different points. The more the atrophy, the more severe the disease will get. Numerous studies have shown that early detection of AD can improve the prognosis of patients. Because of how readily available this technology is in Europe and North America, patients can quickly get this study done to check for atrophy. Unfortunately, you are not able to sample the tissue of the brain at the same time to determine if there are any clear-cut histological changes that can confirm a diagnosis of AD without a doubt. Patients who also have metal implants, piercings or tattoos are also unable to have this test in some cases due to the risk of being in such a strong magnetic field.

How a Computed Tomography scan can help diagnose Alzheimer's

The next useful study that you can use in order to diagnose AD would be Computed Tomography, better known as the CT scan. This is an investigation that is more readily used in hospitals because of the speed and comfort for the patient and the doctor. Unlike the MRI scan, this type of investigation does not require the use of a magnetic field so patients with metal implants have no contraindications for this investigation. This is an investigation that makes use of the simple X-ray but on a much larger scale. Patients will be passed through a scanner that will take pictures using multiple X-rays and actually build a picture of what the internal structures appear to be. This is a much quicker examination for patients and can be completed in as little as 15 minutes in most cases. 

This is a test that will be used to help doctors rule in and rule out potential causes of dementia that are expected in patients with AD. This can help doctors look for the presence of tumors, strokes or hemorrhages that could also cause a similar decline in the functionality of the brain. The ventricular size of the brain can also be noted quite easily in patients having a CT scan. This allows doctors another chance to rule out other causes of dementia quickly in order to diagnose the disease quicker. This is a very safe investigation for patients to have but because of the sheer volume of X-rays that are being taken at one time, it is important for patients to not have this investigation too often in order to reduce their chances of radiation poisoning. 

PET imaging may also be used while diagnosing Alzheimer's

Positron-Emissions Tomography, or the PET scan, is the last type of investigation that we will spotlight in this article. There is no need to get into the complicated physics of what is happening to explain how this instrument works but the simple version may be helpful. This is a type of study that is used to determine how much glucose (or sugar) is being used by tissue. This can give a reasonable representation of how quickly the brain is metabolizing the sugar. The more active an area, the more glucose will be needed in order to maintain these functions. 

The application of this PET scan in the diagnosis of AD is apparent in modern medicine. There are numerous studies that have shown the PET scan to be a very good tool in diagnosing the early changes in the brain. It is also able to differentiate more precisely between normal aging and patterns likely seen only in AD patients. Another advantage of this type of investigation is that it can produce models that can predict the speed of memory decline. This can help doctors target specific treatments and identify symptoms that may become more pronounced depending on the region of the brain involved. 

All of these modalities are important in the diagnosis of AD. Patients can benefit from even a single brain imaging study in order to diagnose the disease but the best findings can occur when doctors combine different scans in order to get a more clear picture of what is occurring. The standard combination would typically be a CT and PET scan or MRI and PET scan. 

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