Author: Michael Hoch, MD

Multiple sclerosis – white spots and red flags – part 2

Posted on by Michael Hoch, MD

Multiple sclerosis – white spots and red flags – part 2

Mimics and Variants

Demyelinating disease is a common situation we encounter in neuroradiology, and properly diagnosing and tracking it using MRI is a key skill for neuroradiologists. In this second part of the lecture, Dr. Michael Hoch gives us some tips about other causes of white matter lesion, and information we can use to make our imaging diagnosis of multiple sclerosis more specific.

Clinical history has an important role in determining how specific imaging findings are for multiple sclerosis. Some features may suggest that a patient does not have multiple sclerosis, such as if they are the wrong age (< 20 or > 50 years old), if they have abrupt swift progression, if they have systemic symptoms such as fever or weight loss, and if they have uncommon CNS symptoms such as a movement disorder or meningitis signs. MS lesions also usually occur in some specific locations, such as in the corpus callosum, temporal lobe, periventricular white matter, and juxtacortical white matter.

Mimics of Multiple sclerosis

So, what are some of the common mimics of MS?

Migraine – migraine is the most common cause of non-specific white matter abnormalities in young patients, occurring in more than 50% of patients with migraine

Chronic small vessel ischemia – more common with increasing age, and worsening with risk factors such as diabetes, hypertension, and smoking

CNS vasculitis – an inflammatory syndrome of the intracranial vessels. Be on the lookout if someone has a history of TIAs or thunderclap headache, or systemic symptoms.

Behcet’s disease – a vasculitis most common in young males, characterized by brainstem involvement and oral ulcers

Susac syndrome – an autoimmune microangiopathy overlapping MS in age distribution. However, patients more often have a triad of encephalopathy, hearing loss, and visual changes. Corpus callosum involvement is more likely to be central. 

CADASIL – an autosomal dominant syndrome characterized by frequent infarcts. Look out for the characteristic locations in the temporal poles, external capsules, and paramedian superior frontla lobes. It is also usually quite symmetric.

Other rarer mimics are Neuro-Sweets disease and Lyme disease, which can cause white matter abnormalities.

Key take home points of this lecture include:

  • Multiple sclerosis is a clinical diagnosis, not an MRI diagnosis
  • White spot lesion location matters
  • Juxtacortical lesions must touch the cortex
  • Aggressively window the spine to look for cord lesions
  • Leptomeningeal enhancement is possible in multiple sclerosis

Variants of demyelinating disease

There are several common variants that you should know about across the demyelinating spectrum:

ADEM – acute disseminated encephalomyelitis – an autoimmune mediated and often self limited fulminant demyelinating process. May be related to a viral illness or vaccination.

Marburg disease – a clinically fulminant demyelinating disease usually affecting younger patients with a febrile prodrome.

Balo concentric sclerosis – a rare and monophasic demyelinating disease characterized by large lesions with alternating zones of demyelination/myelination

Tumefactive demyelinating lesions (TDL) – large and often fulminant demyelinating lesions that have mass effect and can mimic tumors. Perfusion imaging with low blood volumes can help differentiate from masses.

Neuromyelitis optica (NMO) – a demyelinating syndrome characterized by post-chiasmatic optic neuritis and long segment spine lesions. This is mediated by an aquaporin-4 antibody.

Progressive multifocal leukoencepalopathy (PML) – a JC virus mediated demyelinating lesion that occurs in immune suppressed patients. Usually has little or no enhancement and favors a subcortical location.

Summary

In summary, there are a couple of key things to keep in mind when evaluating potential demyelinating lesions:

  • Read the chart for clinical red flags
  • Look at the MRI for imaging red flags, like strokes, hemorrhages, cysts, findings that are too symmetric, subcortical, or normal
  • Remember that white matter lesions from migraine and microvascular disease are far more common that multiple sclerosis
  • NMO has differentiating features
  • PML is a rare complication of immune suppressing medications in MS patients

 

The level of this lecture is appropriate for radiology residents, radiology fellows, and trainees in other specialties who have an interest in imaging or treating patients with potential demyelinating diseases.

This video is part of a two part series on multiple sclerosis presented by Dr. Hoch.

If you haven’t seen it already, go back and check out part 1, in which Dr. Hoch discusses the key findings of demyelinating lesions.

Multiple Sclerosis: White Spots & Red Flags

Posted on by Michael Hoch, MD

Multiple sclerosis – white spots and red flags

Demyelinating disease is a common situation we encounter in neuroradiology, and properly diagnosing and tracking it using MRI is a key skill for neuroradiologists. In this two part lecture, Dr. Michael Hoch instructs us on how to approach white matter abnormalities in the brain and use them towards making a diagnosis of multiple sclerosis. The first part is focused on key tips on making a diagnosis of demyelinating disease while the second is focused on potential pitfalls.

Be sure to watch them both to get the complete overview of imaging findings of common autoimmune and inflammatory conditions.

Multiple sclerosis – white spots and red flags – part 1

Posted on by Michael Hoch, MD

Multiple sclerosis – white spots and red flags – part 1

Making the diagnosis

Demyelinating disease is a common situation we encounter in neuroradiology, and properly diagnosing and tracking it using MRI is a key skill for neuroradiologists. Today, Dr. Michael Hoch gives the first part of a two part lecture on how to approach white matter abnormalties in the brain and use them towards making a diagnosis of multiple sclerosis.

Multiple sclerosis is a clinical diagnosis that depends on several possible presenting signs (such as depression, fatigue, vertigo, numbness or other neurological symptoms, bladder dysfunction, visual changes, or other phenomena including L’Hermitte’s sign or Uhthoff’s phenomenon) and other clinical sign (including tremor, decreased perception, hyperreflexia, and ataxia).

The imaging diagnosis of multiple sclerosis is based on the McDonald criteria, most recently revised in 2017. This requires dissemination in space, dissemination in time, and lack of an alternate explanation. You should evaluate different spaces for white matter abnormality, including the cortex, juxtacortical, subcortical and deep white matter, corpus callosum, and deep white matter, periventricular white matter. 

The locations of the lesions can provide a clue as to whether white matter lesions are more likely to be caused by demyelinating disease or other nonspecific insults, such as chronic microvascular ischemia. For instance, central lesions in the pons or lesions in the deep white matter are more nonspecific, while cortical/juxtacortical, periventricular, and anterior temporal lesions are more specific for multiple sclerosis.

The enhancement pattern is also a clue to whether a lesion might be demyelinating. Demyelinating lesions typically have an incomplete rim of enhancement, where the post-contrast enhancement has a broken circle type of appearance. Leptomeningeal enhancement can often be seen in patients with MS, although it is an alarm bell if patients don’t have a known diagnosis, as it can represent other diseases such as leptomeningeal carcinomatosis.

Key take home points of this lecture include:

  • Multiple sclerosis is a clinical diagnosis, not an MRI diagnosis
  • White spot lesion location matters
  • Juxtacortical lesions must touch the cortex
  • Aggressively window the spine to look for cord lesions
  • Leptomeningeal enhancement is possible in multiple sclerosis

 

The level of this lecture is appropriate for radiology residents, radiology fellows, and trainees in other specialties who have an interest in imaging or treating patients with potential demyelinating diseases.

This video is part of a two part series on multiple sclerosis presented by Dr. Hoch.

For the next part of the lecture, check out part 2, in which Dr. Hoch discusses potential mimics and pitfalls when assessing for demyelinating disease.

Brain MRI – Seizure search pattern

Posted on by Michael Hoch, MD

Brain MRI – Seizure search pattern

Many times when patients have a history of seizures, they undergo a workup including a physical exam, detailed EEG analysis, and finally brain MRI to try to identify any potential structural causes of seizures. In this video, Dr. Michael Hoch walks us through his approach to a brain MRI to maximize your sensitivity for finding abnormalities.

 

Dr. Hoch suggests a 4-step approach using the mnemonic “3-2-1 go to the hippocampus”. In this way, he divides his search into more digestible parts.

“3” indicates the 3 planes that you have in a non-contrast T1 weighted MP-RAGE MRI. On this you should focus on the cortex, particularly at the 3 poles, the frontal, temporal, and occipital poles.

“2” indicates the 2 planes of FLAIR and 2 window settings you should use. You should review FLAIR images in both the coronal and axial planes. You should also use a window that is normal and a window that is narrow, or aggressive, to highlight lesions, particularly in the cortex, which are hard to see.

“1” indicates the single plane of blood sensitive imaging, either GRE or SWI, which can often see areas of prior hemorrhage or cavernou

“Go” to the hippocampus last to look for signs of mesial temporal sclerosis, which is manifested as a small hippocampus with loss of internal architecture and abnormal T2/FLAIR hyperintensity. This can be either from primary epilepsy or secondary to another lesion.

See this and other videos on our Youtube channel .

Neuroradiology physics review – 1 – Computed Tomography

Posted on by Michael Hoch, MD

Neuroradiology physics review – 1 – Computed Tomography

It’s important for the neuroradiologist to have a basic grasp of physics, particularly in the ways that it may affect image quality. In this video, Dr. Michael Hoch goes through a series of 12 CT cases on physics. Each case is followed by multiple choice questions about that physics principle.

There are a number of ways that physics principles affect images, causing various types of suboptimal images, such as:

  • partial volume averaging – when an object only takes up part of a voxel and the resulting output
  • patient motion – when patient moves during imaging, degrading image quality and causing image blurring
  • streak artifact – when high density material adversely affects CT reconstruction, causing lines across an image
  • ring artifact – when a detector fails and causes rings through the image
  • contrast staining – when breakdown of the blood brain barrier allows leakage of contrast into the brain

Other key principles discussed include:

  • pitch
  • computed tomography dose index (CTDI)
  • dose length product (DLP)
  • pre- and post-patient collimation
  • image filtration

The level of this lecture is appropriate for radiology residents, radiology fellows, and trainees in other specialties who would like to review radiology physics. This may be particularly useful when preparing for the American Board of Radiology (ABR) core and certifying exams.

Youtube Playlist 

Advanced MRI imaging of the brain

Posted on by Michael Hoch, MD

Advanced MRI imaging of the brain

There are several advanced MRI techniques for more sophisticated imaging of brain structure and function. The most common advanced imaging techniques include spectroscopy, perfusion, diffusion tensor imaging (DTI), and functional MRI (fMRI). This playlist shows some of the details of using advanced imaging techniques for brain imaging and surgical planning.

This playlist includes some of the details about using advanced MRI for surgical planning and determining additional details about brain MRI.

Functional MRI (fMRI) language localization – conjunction display

Posted on by Michael Hoch, MD

Functional MRI (fMRI) language localization – conjunction display

Blood oxygen level dependent functional MRI, or BOLD fMRI, is an advanced MRI technique in which level of oxygen present in an area of the brain is used to map out what parts of the brain are activated in specific tasks. In this method, repeated imaging of the brain can be performed while the patient performs a task, and the level of oxygenation changes, showing which parts of the brain are most activated.

A key application of fMRI is mapping of language areas, or language localization, for surgical planning. The patient will perform more than 1 language task while in the scanner, and the activation data is overlaid on anatomic imaging (like conventional T1 or T1 postcontrast imaging). This is used to determine which side of the brain is language dominant as well as where exactly important language areas, including Broca’s and Wernicke’s areas, are located. This way they can be avoided in complex surgical procedures. However, sometimes results can be difficult to interpret because of the high number of images and high amounts of noise.

In this video, Dr. Michael Hoch demonstrates how use a conjunction technique to increase sensitivity for mapping language areas. In this method, all the language paradigms are overlaid on a single set of images using different colors. This increases the visibility of otherwise hard to see areas, increasing reader confidence.

The level of this lecture is appropriate for radiology residents, radiology fellows, and trainees in other specialties who have an interest in advanced MRI techniques such as diffusion tensor imaging (DTI) tractography, functional MRI (fMRI), and surgical planning.

For more information, see the whole video playlist on Advanced MRI.

 

Functional MRI (fMRI) Brainlab Processing Guide

Posted on by Michael Hoch, MD

Functional MRI (fMRI) Brainlab Processing Guide

Blood oxygen level dependent functional MRI, or BOLD fMRI, is an advanced MRI technique in which level of oxygen present in an area of the brain is used to map out what parts of the brain are activated in specific tasks. In this method, repeated imaging of the brain can be performed while the patient performs a task, and the level of oxygenation changes, showing which parts of the brain are most activated.

A key application of fMRI is mapping of language areas, or language localization, for surgical planning. The patient will perform more than 1 language task while in the scanner, and the activation data is overlaid on anatomic imaging (like conventional T1 or T1 postcontrast imaging). This is used to determine which side of the brain is language dominant as well as where exactly important language areas, including Broca’s and Wernicke’s areas, are located. This way they can be avoided in complex surgical procedures. However, sometimes results can be difficult to interpret because of the high number of images and high amounts of noise.

There are a number of processing suites that you can use to process fMRI data, including Brainlab and Dynasuite. The processing can be slightly different depending on which software package you are using, but the general principles are the same. To begin, you take each functional paradigm and overlay it on anatomical imaging, selecting statistical parameters and colormapping as you go.

In this video, Dr. Michael Hoch demonstrates the use of Brainlab to process fMRI data for language processing. He goes through the step-by-step process of generating each set of overlay imaging and how to interpret the results. In the second part of the video, he demonstrates conjunction overlay technique to increase sensitivity for mapping language areas by showing only the areas which have overlapping results on multiple paradigms, increasing reader confidence.

The level of this lecture is appropriate for radiology residents, radiology fellows, and trainees in other specialties who have an interest in advanced MRI techniques such as diffusion tensor imaging (DTI) tractography, functional MRI (fMRI), and surgical planning.

For more information, see the whole video playlist on Advanced MRI.

MRI Diffusion Tensor Imaging (DTI) interpretation – locating the corticospinal tract (CST)

Posted on by Michael Hoch, MD

MRI Diffusion Tensor Imaging (DTI) interpretation:
Locating the corticospinal tract (CST)

Diffusion tensor imaging, or DTI, is an advanced MRI technique in which the asymmetric motion of water is used to map out specific properties in the brain. One application of DTI is called tractography, or identifying the specific tracts of neurons which pass through the brain.

One of the most important fiber tracts in the brain is the corticospinal tract, or CST. This tract connects the motor cortex with the spinal cord, passing through the cerebral peduncles. This fiber tract is important because it is the tract most responsible for voluntary movement. It can be affected by a number of pathologies, such as tumors, cortical malformation, and stroke. For some conditions, such as tumors, it can be critically important to locate the CST before performing surgery, so that the surgeons can properly plan their surgery. That’s where DTI comes in.

In this video, Dr. Michael Hoch demonstrates how to use a two region of interest method to identify the corticospinal tract, first placing a region of interest in the cerebral peduncle and a second in the motor cortex. He also talks about some of the pitfalls of diffusion tensor imaging and what kind of problems to look out for.

The level of this lecture is appropriate for radiology residents, radiology fellows, and trainees in other specialties who have an interest in advanced MRI techniques such as diffusion tensor imaging (DTI) tractography, functional MRI (fMRI), and surgical planning.

For more information, see the whole video playlist on Advanced MRI.