Related Experiment Video
Updated: Jan 21, 2026
16:49
Multifocal Electroretinograms
Published on: December 4, 2011
18.8K
Cortical hypointensity in T2-weighted gradient-echo sequences in patients with progressive multifocal
P López Sala1, N Alberdi Aldasoro1, M V Zelaya Huerta2
1Servicio de Radiodiagnóstico, Complejo Hospitalario de Navarra, Pamplona, Navarra, España.
Radiologia
|August 4, 2019
Summary
Cortical hypointensity on T2-weighted gradient-echo MRI is a useful diagnostic sign for progressive multifocal leukoencephalopathy (PML). This finding supports PML diagnosis across various immunosuppression types, aiding early detection in at-risk patients.
Area of Science:
- Neurology
- Radiology
- Infectious Diseases
Background:
- Progressive multifocal leukoencephalopathy (PML) is a demyelinating CNS disease caused by JC virus reactivation.
- It primarily affects immunocompromised individuals, including those with advanced HIV or on immunosuppressive therapies like natalizumab.
- Magnetic Resonance Imaging (MRI) is crucial for diagnosing and monitoring PML.
Observation:
- Recent studies suggest cortical hypointensities on specific MRI sequences (T2-weighted gradient-echo, susceptibility-weighted imaging) may indicate PML.
- This study investigated the presence and diagnostic utility of cortical hypointensity on T2-weighted gradient-echo sequences.
- Three cases of PML in patients with diverse immunosuppression (HIV, natalizumab, rituximab) were analyzed.
Findings:
- All three cases demonstrated cortical hypointensity adjacent to white matter lesions on T2-weighted gradient-echo MRI.
- In one case (multiple sclerosis treated with natalizumab), this sign preceded white matter abnormalities.
- Postmortem pathological findings confirmed MRI correlations in the rituximab-treated patient.
Implications:
- Cortical hypointensity on T2-weighted gradient-echo MRI appears to be a reliable indicator for diagnosing PML.
- This finding is valuable irrespective of the underlying cause of immunosuppression.
- Routine assessment of cortical hypointensity is recommended for patients suspected of having PML.
Related Concept Videos
01:06Echo
911
The human ear cannot distinguish between two sources of sound if they happen to reach within a specific time interval, typically 0.1 seconds apart. More than this, and they are perceived as separate sources.
Imagine the sound is reflected back to the ears. Assuming that the source is very close to the human, the difference between hearing the two sounds—the emitted sound and the reflected sound—may be more than the minimum time for perceiving distinct sounds. If this is the case,...
Imagine the sound is reflected back to the ears. Assuming that the source is very close to the human, the difference between hearing the two sounds—the emitted sound and the reflected sound—may be more than the minimum time for perceiving distinct sounds. If this is the case,...
911
01:26What is an Electrochemical Gradient?
127.4K
Adenosine triphosphate, or ATP, is considered the primary energy source in cells. However, energy can also be stored in the electrochemical gradient of an ion across the plasma membrane, which is determined by two factors: its chemical and electrical gradients.
The chemical gradient relies on differences in the abundance of a substance on the outside versus the inside of a cell and flows from areas of high to low ion concentration. In contrast, the electrical gradient revolves around an...
The chemical gradient relies on differences in the abundance of a substance on the outside versus the inside of a cell and flows from areas of high to low ion concentration. In contrast, the electrical gradient revolves around an...
127.4K
00:57Weighted Mean
6.2K
While taking the arithmetic, geometric, or harmonic mean of a sample data set, equal importance is assigned to all the data points. However, all the values may not always be equally important in some data sets. An intrinsic bias might make it more important to give more weightage to specific values over others.
For example, consider the number of goals scored in the matches of a tournament. While computing the average number of goals scored in the tournament, it may be more important to...
For example, consider the number of goals scored in the matches of a tournament. While computing the average number of goals scored in the tournament, it may be more important to...
6.2K
01:19Mass and Weight
15.1K
Mass and weight are often used interchangeably in everyday conversation. For example, medical records often show our weight in kilograms, but never in the correct units of newtons. In physics, however, there is an important distinction. Weight is the pull of the Earth on an object. It depends on the distance from the center of the Earth. Weight dramatically varies if we leave the Earth's surface, unlike mass, which does not vary with location. On the Moon, for example, the...
15.1K
01:25Atomic Weight
11.7K
Protons and neutrons have approximately the same mass, about 1.67 × 10-24 grams. Scientists arbitrarily define this amount of mass as one atomic mass unit (amu) or one Dalton. Electrons are much smaller in mass than protons, weighing only 9.11 × 10-28 grams, or about 1/1800 of an atomic mass unit. As a result, they do not contribute much to an element's overall atomic mass. This means that, when considering atomic mass, it is customary to ignore the mass of any electrons and...
11.7K
01:09Apparent Weight
9.8K
True weight is the measure of the gravitational force acting on an object. However, if the object accelerates, its measured weight is different from its true weight. Similar observations can be made when the object is submerged in water. An object's weight in water is its apparent weight, which is equal to the difference between its true weight and the buoyant forces.
Consider a person standing on a bathroom scale inside an elevator. If the scale is accurate at rest, its reading equals the...
Consider a person standing on a bathroom scale inside an elevator. If the scale is accurate at rest, its reading equals the...
9.8K