The open-ring enhancement pattern with low signal T2 ring and low CBF are all indicative of demyelination. Balo's Concentric Sclerosis is an uncommon demyelinating disease. It is characterized by alternative bands of demyelination and myelin preservation, often in whorl-like configurations. Here T2 and postcontrast T1W images showing a large lesion in the left hemisphere with alternating T2-hyperintense and isointense bands. On the T1W images after gadolinium there is alternating linear enhancement.
There is a smaller, similar lesion on the right. A very important differential to keep in mind, especially in patients with a bilateral optic neuritis, is Neuromyelitis Optica NMO or Devic's Disease.
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This is a demyelinating disease in which the optic nerves and spinal cord are usually involved. Often there are few T2-lesions in the brain. Think of NMO when there are extensive spinal cord lesions more than 3 vertebral segments with low T1-signalintensity and swelling of the cord. On axial images the lesions often involve most of the cord.
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This is unlike MS, in which the lesions are usually smaller and peripherally located. Here we see a sagittal T2-weighted image of the spinal cord in a patient with NMO showing a longitudinally extensive cord lesion with marked swelling. Read more on NMO in the spinal cord This is a monophasic, immune-mediated demyelinating disease which often presents in children following an infection or vaccination. On MRI there are often diffuse and relatively symmetrical lesions in the supra-and infratentorial white matter which may enhance simultaneously.
There almost always is preferential involvement of the cortical gray matter and the deep gray matter of the basal ganglia and thalami. The diagnosis of MS requires elimination of more likely diagnoses and demonstration of dissemination of lesions in space and time. The McDonald criteria for MS were recommended in by an international panel and revised in and Excludes pseudoattacks, single paroxysmal symptoms multiple episodes of paroxysmal symptoms occurring over 24 hours or more are acceptable as evidence. The McDonald criteria make use of the clinical presentation and the advances of MR imaging.
When a patient presents with 2 or more attacks with clinical evidence of 2 or more neurological deficits, there is no need for additional requirements to make the diagnosis of MS, because there is dissemination in place and time. In all other cases less than 2 attacks or less than 2 clinical lesions there is a role for MRI to fulfill the diagnostic criteria by demonstrating dissemination in space, in time or both.
You do not want a patient to start treatment daily if there is any doubt about the diagnosis. Gadolinium is administered at the start of the examination because the longer you wait the more enhancement you will see on the T1W images MS lesions are not spontaneously bright on T1-weighted images without contrast administration. A scout with additional mid-sagittal T1WI is made for optimal and constant positioning. The sagittal FLAIR is ideal for detection of lesions in the corpus callosum and the 3D sequence allows for better detection of smaller and juxtacortical lesions.
Finally the axial T1W-images are made after about 15 minutes to provide optimal contrast enhancement. Coronal and midsagittal scout views are needed for reproducible positioning of the slices, so you are able to compare follow-up studies. Use the coronal scout to plan the true midsagittal image parallel to the falx and other midline structures. On a true midsagittal image a line is drawn through the pituitary gland and the roof of the fourth ventricle fastigium. This is called the HYFA: hypophysis-fastigium line. Subsequently the slices are positioned with the middle slice at the lower border of the splenium of the corpus callosum.
Gadolinium is not necessary when only the spinal cord is examined. Contrary to the brain there will only rarely be enhancement in the cord.
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Only when other diagnoses are considered e. When we look at the prevalence of the white matter diseases, you will notice that there are enormous differences. Hereditary diseases are extremely uncommon as individual diseases, but as a group they are not that uncommon, but still far more uncommon than MS.
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If we look at the prevalence of Lyme disease, which is a rather popular disease at the moment, then we will notice that it still is a very uncommon disease despite of all the serological tests that are being performed nowadays. They are more common in older people and in patients with vascular risk factors like atherosclerosis, high blood pressure, high cholesterol, diabetes, amyloid angiopathy, hyperhomocysteinemia, atrial fibrillation etc. If a patient is clinically suspected of having MS and the MR-images support that diagnosis, than you should not consider the possibility of Lyme's disease and neuro-SLE in the differential diagnosis, because they have such a low prevalence.
There must be other ways to impress your colleagues. These diagnoses are only worth mentioning if there are clinical findings that support these diagnoses. Consequently, it is not wise to put MS in the differential diagnosis if the clinician does not suspect the patient of having MS and on the MR incidental WMLs are found. On the other hand if a patient is clinically suspected of having MS and multiple WMLs are found, our major concern is the differential diagnosis MS versus vascular disease and we have to follow the McDonald criteria. The differential diagnosis of white matter lesions is extremely long.
The most common inflammatory disease is Multiple Sclerosis. Inherited diseases usually will have symmetrical abnormalities, so they have to be differentiated from intoxications.
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On the left a collection of images with multiple punctate and patchy lesions in the WM. Some will be discussed in more detail. There is no complete overlap between the images on the left and the text on the right. Borderzone infarction Key finding : typically these lesions are located in only one hemisphere, either in deep watershed area or peripheral watershed area.
In the case on the left the infarction is in the deep watershed area.
Different from MS is that the lesions are often large and in a younger age group. The disease is monophasic. Lyme mm lesions simulating MS in a patient with skin rash and influenza-like illness. Other findings are high signal in spinal cord and enhancement of CN7 root entry zone. Sarcoid Sarcoid is the great mimicker. The distribution of lesions is quite similar to MS.
PML may be unilateral, but more often it is bilateral and asymmetrical. Click here for more information.
Small vessel disease WMLs in the deep white matter. Not located in corpus callosum, juxtaventricular or juxtacortical. In many cases there are also. On the left a collection of images with multiple enhancing lesions in the WM. Vasculitis Most diseases with vasculitis are characterized by punctiform enhancement. Behcet Behcet is more commonly seen in Turkish patients. Typical findings are brainstem lesions with nodular enhancement in the acute phase.
Borderzone infarction Peripheral border zone infarctions may enhance in the early phase. On the T2W image there are multiple high intensity lesions in the basal ganglia. This signal intensity in combination with the location is typical for VR spaces.
Virchow Robin spaces are CSF spaces around penetrating leptomeningeal vessels. They are typically located in basal ganglia, around atria, near the anterior commissure and in the middle of the brainstem. Usually they are small except around the anterior commissure, where perivascular spaces can be larger. On this image we see both very wide VR spaces as well as confluent hyperintense lesions in the WM.