Adrenoleukodystrophy is an inherited neurodegenerative disease caused by a mutation in the ABCD1 gene. This mutation leads to the accumulation of compounds called very long-chain fatty acids (VLCFA) inside cells. This accumulation causes the protective myelin sheath surrounding nerve fibers to be destroyed. This destruction or demyelination leads to the appearance of lesions in the brain, which can be visualized using magnetic resonance imaging (MRI).
MRI is a powerful imaging technique used to visualize organs and tissues. It can generate clear and detailed images of different sections of the brain.
It uses magnets and radio waves to create high-resolution images instead of the harmful radiations used in other medical scanning techniques such X-rays and CT. Radio waves do not generally pose any risk to the body, making MRI a safe procedure.
The body contains a significant amount of water, which is made up of hydrogen and oxygen, and its concentration varies by tissue type. The MRI scanner generates a magnetic field that is strong enough to align the protons present in the hydrogen atom.
Bursts of external radio-frequency signals are then used to perturb the aligned protons. When the protons release energy between each burst, they emit radio signals that are detected by sensors within the scanner.
Because protons from different tissue types take different times to return to the aligned state, the scanner can distinguish among the different tissue types.
MRI and ALD
Brain abnormalities in ALD can develop before any neurological or behavioral symptoms appear. Detailed brain MRI scans can identify signs of the damage, locate lesions, and help in disease diagnosis.
MRI scans are usually recommended following diagnosis using genetic testing. The first MRI scan provides a baseline image of the level of damage at diagnosis. Follow-up scans are normally performed every six to 12 months. Once symptoms appear, frequent MRI becomes critical to monitor disease progression.
The doctors grade the brain scans from zero to 34 based on the severity of the abnormality. A score of 14 or more is considered severe. The next course of action is determined based on the scoring.
Things to know
MRI is the preferred imaging technique for soft tissues such as muscles, nerves, and blood vessels, and can image their difference in detail. Thus, MRI scans are highly sensitive and specific in highlighting abnormalities.
MRI scanners are fitted with large magnets. Therefore, scanning is not performed on patients with metal implants, pacemakers, shrapnel, and some tattoos. Although MRI is a relatively safe procedure, it is avoided in pregnant women unless absolutely necessary.
The scanners are large machines. The patient has to lie still on a flatbed that is moved into a tube-like opening in the scanner for imaging. This narrow, confined space within the scanner may cause discomfort to people with claustrophobia. For such patients, radiologists and technicians can provide mild medication or virtual reality (VR) aids for relaxation, if available. Such VR aids are also available for children who may find it difficult to lie still for the duration of the scan.
On average, the procedure takes about 45 minutes to an hour. During imaging, it can get loud within the scanner because of noises from the machine. This is normal, but may be uncomfortable for some patients. Most centers provide earplugs to block out the noise.
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