Multiple sclerosis is a complex condition that affects the central nervous system, which is composed of the brain and spinal cord. The disease involves the immune system damaging the protective covering of nerves, known as myelin. This damage disrupts the flow of information between the brain and the body, leading to a wide range of neurological symptoms. Diagnosing the disease involves a combination of clinical evaluation and specialized scans to visualize its effects inside the body.
The Role of X-rays in Medical Imaging
X-ray imaging is a medical tool that uses electromagnetic radiation to create pictures of the body’s internal structures. The technology works by passing X-ray beams through the body, which are absorbed at different rates by different tissues. Dense materials, such as bone, absorb a significant amount of radiation and appear white on the resulting radiograph, making X-rays effective for visualizing the skeletal system.
Consequently, X-rays are used to diagnose conditions like bone fractures, joint dislocations, and dental issues. They are also effective for examining the chest to identify certain lung conditions. The procedure is fast, convenient, and widely available in most healthcare settings.
While effective for viewing hard, dense tissues, standard X-rays have limitations with soft tissues. Structures like muscles, ligaments, nerves, and organs have similar densities and do not absorb X-rays as effectively as bone. This results in images where these soft tissues are difficult to distinguish from one another.
Limitations of X-rays for Diagnosing Multiple Sclerosis
The defining characteristic of multiple sclerosis is the presence of lesions, which are areas of damage and inflammation, on the nerve fibers of the brain and spinal cord. This damage targets the myelin sheath, a fatty substance that insulates nerves. Myelin, along with the nerves and brain, are all considered soft tissues.
Because X-rays are not well-suited for creating detailed images of soft tissues, they cannot detect the subtle changes caused by MS. An X-ray image cannot differentiate the small areas of demyelination from the surrounding healthy brain or spinal cord tissue, as the technology lacks the necessary contrast.
Therefore, X-rays are not used to diagnose multiple sclerosis. While an X-ray can show the bones of the skull and spine with great clarity, it cannot reveal the state of the soft neural tissue housed within them.
Standard Imaging for Multiple Sclerosis Diagnosis and Monitoring
The primary imaging tool for diagnosing and monitoring multiple sclerosis is Magnetic Resonance Imaging (MRI). Unlike X-rays, MRI does not use ionizing radiation. It employs powerful magnets, radio waves, and a computer to generate highly detailed images of the body’s soft tissues, making it effective for visualizing the brain and spinal cord.
An MRI can clearly show the lesions or plaques associated with MS. These areas of damage appear as distinct spots on the scan, allowing neurologists to assess their size, number, and location. This information is important for diagnosis, as the McDonald criteria—the standard guidelines for diagnosing MS—rely on evidence of damage in different parts of the central nervous system at different points in time.
To gain more information, a contrast agent called gadolinium is often injected into the patient’s bloodstream before the MRI scan. This dye highlights areas of active inflammation by leaking through the blood-brain barrier, which becomes permeable during an MS relapse. Lesions that enhance with gadolinium are considered “active,” indicating new disease activity, which helps in diagnosis and monitoring.
When X-rays Are Used for Patients with Multiple Sclerosis
Although X-rays cannot diagnose MS, they play a role in managing the health of individuals with the condition. People with MS may experience secondary health issues for which an X-ray is the appropriate diagnostic tool. These tests are ordered to evaluate other parts of the body for unrelated or resultant problems.
Mobility and balance can be affected by MS, which may increase the risk of falls, and an X-ray is the standard procedure to check for suspected bone fractures. Difficulties with swallowing, known as dysphagia, can also occur in some individuals with MS. This can lead to aspiration pneumonia if food or liquid enters the lungs, and a chest X-ray is a common method to help diagnose this infection.
Monitoring bone density is also a concern for some people with MS. Reduced mobility and certain steroid treatments used to manage severe MS relapses can contribute to osteoporosis, a condition that weakens bones. A specific type of X-ray, a dual-energy X-ray absorptiometry (DEXA) scan, is used to measure bone mineral density.