MRI Scans and Diagnosing ALS

Magnetic resonance imaging (MRI) is used to identify and diagnose a wide range of health conditions. Taking images of the internal body structure using a series of magnets and radio waves, it is often used in the diagnosis of ALS to help medical professionals exclude the possibility of other potential conditions. However, research has suggested that MRI scans may well be used as a more focused diagnostic tool in the near future.

Diagnosing a disease such as ALS is generally not just a simple case of listing the symptoms. This may well be a starting point for doctors, but further investigation will be needed before a full and accurate diagnosis is made.

If a physician suspects a condition such as ALS, the first thing that needs to be done is to have the individual assessed by a neurologist. They will start with a physical exam, which will look at any symptoms that are present. They will also examine the patient’s personal and family medical history.

Initial symptoms of ALS might include slurred speech, muscle twitching, muscle weakness and issues such as difficulty walking or problems with balance. During the diagnosis, a number of tests can be carried out. Many of these are used to exclude other potential conditions and are not signifiers of ALS being present in itself.

One test that is routinely carried out in the diagnostic process for ALS is an MRI scan. Here we take a closer look at this particular process, what it involves and how MRI scans may have a greater role to play in the future.

What is an MRI Scan?

Magnetic resonance imaging uses a combination of radio waves and a magnetic field to produce detailed pictures of the internal body.

MRI scans are used to exclude the possibility of other conditions being the cause of the patient’s symptoms.

However, there are studies that suggest it can be used to diagnose ALS by identifying specific biomarkers that are related to the disease.

The evidence so far is limited and more research is needed, but the initial findings offer the potential for an exciting new development in the process of diagnosing ALS.

Types of MRI Scan

There are a number of different types of MRI scan that may be used to help with the detection and diagnosis of ALS. The main ones used include:

• Structural MRI: This can detect changes in gray and white matter in the central nervous system and is a useful tool in ruling out other conditions.
• Voxel-based morphometry or VBM: This is actually a statistical tool that compares differences between subjects in brain anatomy and is sensitive to spotting changes in neuronal structure.
• Diffusion tensor imaging or DTI: This is one area that may prove potentially vital in the direct detection of changes caused by ALS. It works by monitoring changes in water movement and it enables us to detect the causes and effects of a particular disease.
• Functional MRI or fMRI: This method can monitor activity in the brain when someone performs a specific task and may be able to detect ALS related differences such as when an individual is compensating for weakness in a specific muscle group.
• Magnet resonance spectroscopy or MRS: This is related to MRI but identifies chemical changes. It has increasing potential to help the diagnosis of ALS as more is understood about the mechanism of the disease.

What Happens During an MRI Scan?

Whilst MRI equipment can look quite frightening, it’s a non-invasive technique that is performed safely on individuals every day in hospitals or radiology centers across the USA and throughout the world. .

• The patient is asked to lie down on a table which is then moved into a large tubular scanner.
• Typically the individual will be asked to avoid eating or drinking anything for a specific period of time prior to the scan taking place.
• A contrast dye may be injected into a vein to show up certain areas of the body more clearly.
• The scan normally takes about an hour but this may vary depending on what the patient is being tested for.

The Future of MRI Scans in Diagnosing ALS

MRI scans are useful for excluding the potential of other diseases but cannot be used to definitively diagnose ALS. Not yet anyway.

There have been few studies undertaken in this area and more research needs to be done, but the presence of certain biomarkers may allow physicians in the future to make a quicker and more authoritative diagnosis.  

In the research that has been carried out to date, the low number of subjects and differences in presentation of the disease for individuals has led to variable results.

Larger numbers of participants and more longitudinal studies are needed if we are to fully understand what MRI scans are detecting and whether they can be used to more directly diagnose amyotrophic lateral sclerosis.