A magnetic resonance imaging (MRI) scan provides detailed images of the brain’s soft tissues, helping doctors assess its structure and identify abnormalities. When reading the scan, radiologists look for deviations from normal tissue appearance. The term “plaque” is often used by patients to describe an abnormal spot or lesion seen on the scan, representing an area of tissue change or damage. This article clarifies what these spots represent and how doctors interpret these technical findings.
Decoding the MRI Terminology
The term “plaque” is a non-medical word referring to what clinicians call a “lesion” or “hyperintensity” in the brain’s white matter. These areas appear bright white on specific MRI sequences, such as the T2-weighted and the Fluid-Attenuated Inversion Recovery (FLAIR) sequences.
These bright spots indicate a local increase in water content within the tissue, often signaling inflammation, fluid buildup, or demyelination. The FLAIR sequence is particularly useful because it suppresses the bright signal from the cerebrospinal fluid, making abnormal spots stand out clearly. A plaque is not a solid physical buildup, but a visual representation of tissue abnormality holding more water than surrounding healthy tissue.
Vascular and Age-Related Causes
The most common reason for finding these hyperintensities is cerebral small vessel disease, also called microvascular ischemic disease. These findings are common, especially in older adults, and represent damage to the brain’s smallest blood vessels. The spots are sometimes called leukoaraiosis, a descriptive term meaning “rarefaction of the white matter.”
This damage results from long-term problems with blood flow, where small vessels become narrowed or blocked, leading to minor ischemic injury in the white matter. High blood pressure (hypertension), diabetes, and high cholesterol are primary drivers of this small vessel damage. Leukoaraiosis often appears as diffuse, sometimes patchy, white matter hyperintensities located deep within the brain or surrounding the ventricles.
While mild leukoaraiosis may be an incidental finding with no noticeable symptoms, a greater burden of these lesions is associated with an increased risk of cognitive impairment and stroke. These lesions are considered a chronic change, reflecting cumulative minor damage over many years. Their severity is graded to help manage underlying vascular risk factors.
Plaques as Markers for Specific Diseases
Specific patterns of plaques can be the hallmark of more serious neurological conditions beyond age-related vascular changes. Multiple Sclerosis (MS) is a demyelinating disease where the immune system attacks the protective myelin sheath around nerve fibers, creating characteristic lesions. MS plaques are distinguished from vascular lesions by their typical size, shape, and distribution.
These lesions are frequently ovoid (egg-shaped) and are found in specific locations, including the white matter near the ventricles (periventricular), beneath the cortex (juxtacortical), and in the brainstem or cerebellum (infratentorial). Active MS plaques may show enhancement with a contrast agent, indicating active inflammation and a breakdown of the blood-brain barrier. The precise location and shape of these spots are crucial in differentiating MS from other causes of white matter hyperintensities.
Plaques related to amyloid protein are associated with conditions like Cerebral Amyloid Angiopathy (CAA), a common feature in Alzheimer’s disease. In CAA, beta-amyloid protein deposits in the walls of small and medium-sized blood vessels. While CAA can present with white matter hyperintensities, its distinguishing feature on MRI is the presence of cerebral microbleeds. These microbleeds appear as small dark spots, particularly in the outer layers of the brain. The microbleeds indicate a fragile vessel wall prone to rupture, suggesting the white matter changes are related to amyloid pathology rather than simple hypertension.
Evaluation and Interpretation of Findings
An MRI finding is never interpreted in isolation and requires a comprehensive approach to diagnosis. The radiologist’s report describes the imaging findings, but the final diagnosis rests with the treating physician, such as a neurologist. They must correlate the location, number, and appearance of the plaques with the patient’s physical examination, medical history, and specific symptoms.
A few small, non-specific hyperintensities in an older patient with no symptoms are often considered incidental and may simply be monitored. Conversely, new, enhancing lesions in a young patient presenting with acute neurological symptoms prompt aggressive investigation for an inflammatory disease like MS. The clinical context determines the significance of the spots, directing whether further testing or specific treatment is necessary.