Board Review 3 – Case 2

Neuroradiology board review. This lecture is geared towards the ABR core exam for residents, but it would be useful for review for the ABR certifying exam or certificate of added qualification (CAQ) exam for neuroradiology.

More description and the answer (spoiler!) are seen below the video.

This case shows a nodular multifocal mass along the walls of the ventricles. It is relatively low intensity on T2, hyperintense on DWI, and enhances avidly with a nodular solid pattern.

The diagnosis is: CNS lymphoma

Primary CNS lymphoma is a B-cell malignancy with relatively low incidence but overall poor outcomes. It is more common in immunocompromised or HIV patients. The most common locations are in periventricular white matter, the basal ganglia, and the corpus callosum. Solid nodular enhancement, T2 hypointensity, and low ADC values are characteristic. In fact, lower ADC values are associated with a poorer prognosis.

HIV and immunocompromised patients are more likely to have variable enhancement patterns, such as rim enhancement with central necrosis.

Board Review 3 – Full lecture

This lecture is a board review lecture geared towards preparation for the radiology resident ABR core exam, although similar material is used for the ABR certifying exam general and neuroradiology sections.

The format of this lecture is case-based. Each case consists of a series of images followed by 1 or 2 questions. The first question is usually to name the diagnosis, while the second is a multiple choice question to test deeper understanding of the specific condition. Try to get the diagnosis before you see the second questions.

The first 10 cases cover brain tumors and the remaining 9 cover general neuroradiology. The final case will be a high speed multiple choice review.

Board Review 3 – Case 1

Neuroradiology board review. This lecture is geared towards the ABR core exam for residents, but it would be useful for review for the ABR certifying exam or certificate of added qualification (CAQ) exam for neuroradiology.

More description and the answer (spoiler!) are seen below the video.

This case shows a minimally enhancing mass along the anterior part of the septum pellucidum. This patient also has hydrocephalus which may be contributing to the symptoms.

The diagnosis is: subependymoma

Masses in the ventricles and along the septum pellucidum have a broad differential diagnosis, but in this case subependymoma is the best fit because it is a relatively indolent appearing, minimally enhancing mass.

The other possibilities include:

  • ependymoma – usually has more avid enhancement
  • central neurocytoma – also usually has more enhancement
  • subependymal giant cell tumor (SEGT) – possible, but more likely in a patient with tuberous sclerosis
  • choroid plexus tumor – more commonly enhances avidly
  • hemangioblastoma – often will have flow voids
  • metastatic disease – also more avid enhancement

If you see a minimally enhancing ependymal/subependymal tumor, think about subependymoma.

Noncontrast MRI cervical spine search pattern

Magnetic resonance imaging (MRI) of the cervical spine is a very commonly encountered test which can be performed for a variety of indications, including degenerative disease, trauma, demyelinating disease, and metastatic disease. Most of these cases will be done without contrast, as most of the information is there on a non-contrast exam.

This video will walk you through a step-by-step approach to evaluating an MRI of the cervical spine. The optimal approach is to use select sequences to evaluate each part of the study in the following order:

Alignment
Vertebral bodies
Marrow signal
Intervertebral discs
Spinal cord/canal
Soft tissues
Individual levels

Each sequence in the study has strengths at looking at one or more of these things. As we walk through, we’ll take a look at how to use each one.

The level of this lecture is appropriate for medical students, junior residents, and trainees in other specialties who have an interest in neuroradiology or may see patients with spine diseases.

See this and other videos on our Youtube channel.

Neuroradiology physics review – 2 – Magnetic Resonance Imaging

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 13 MRI cases on physics. Each case is followed by one or more multiple choice questions about that physics principle.

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

  • metallic artifacts – areas of signal loss around susceptibility created by metal
  • fat suppression artifacts – areas where fat is incompletely saturated, particularly at the edge of images or adjacent to metal
  • aliasing – where one part of the image is incorrectly mapped to another area due to improper field of view
  • staircase – motion between slices leading to step offs in reconstructed images
  • chemical shift artifact – when a substance such as fat has a different resonance frequency and maps elsewhere into an image
  • zipper/spike artifact – when an external source of frequency noise is mapped into the image domain

Other key principles discussed include:

  • how artifacts may help you make a diagnosis
  • differences in how artifacts may appear on different types of images
  • how to change sequences to mitigate artifact

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.

Check out this video and additional content on https://www.learnneuroradiology.com

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.

https://youtu.be/OeP88BJ5Ec4

Intracranial infections – 5 – Other

There are a few other infectious considerations which have special imaging appearances and which you should keep in mind. This includes neurocysticercosis and Creutzfeldt-Jakob disease (CJD).

This lecture is the final in a series of 5 about imaging intracranial infection and covers diffuse brain infections. The series of videos will cover:
1) General considerations
2) Diffuse infections
3) Focal infection
4) Immunocompromised patients
5) Other considerations

Neurocysticercosis is a brain infection caused by the pork tapeworm. It is a common infection in Latin America and is a common acquired cause of seizure. While the imaging appearance varies with stage, it most commonly has a cystic lesion in the brain parenchyma with peripheral enhancement and surrounding edema. Racemose cysticercosis can involve the CSF spaces, including the ventricles or sylvian fissures. Chronic cysticercosis commonly has punctate peripheral calcification, which can be a clue in patients with this infection.

Creutzfeldt-Jakob disease (CJD) is a prion disease which is commonly thought of as infection because of its association with contaminated beef (bovine spongiform encephalopathy), but most cases (approximately 85%) are spontaneous, with the remainder familial/inherited. Image findings include bilateral symmetric abnormalities of the basal ganglia and thalamus, including signs such as the pulvinar sign or hockey stick (describing thalamic involvement). Cortical linear involvement, or cortical ribboning, is also common.

In summary, there are a variety of infections in the brain ranging from meningitis/encephalitis through focal infections such as abscess and PML. Awareness of these infections is necessary to make an appropriate diagnosis in these patients.

The level of this lecture is appropriate for radiology residents, radiology fellows, and trainees in other specialties who have an interest in neuroradiology or may see patients with CNS infections.

Other videos on the intracranial infection playlist are found here.

 

Intracranial infections – 4 – Immunocompromise

Immunocompromised patients have special considerations for infection of the brain, including HIV encephalopathy, toxoplasmosis, cryptococcus, and progressive multifocal leukoencephalopathy (PML).

This lecture is the fourth in a series of 5 about imaging intracranial infection and covers special considerations in immunocompromised patients. The series of videos will cover:
1) General considerations
2) Diffuse infections
3) Focal infection
4) Immunocompromised patients
5) Other considerations

HIV encephalopathy is a result of direct infection of the white matter in the brain by the HIV virus. It is bilateral, symmetric, and tends to progress over time. There is usually no enhancement.

Toxoplasmosis is the most common opportunistic infection of the brain in HIV patients. Common imaging findings include multifocal masses and enhancement, often involving the basal ganglia. The “target sign”, or bullseye like appearance of the enhancing lesions, is common. The imaging appearance of toxoplasmosis overlaps a great deal with lymphoma, which tends to be more solidly enhancing and involves the periventricular white matter more. Often a treatment trial for toxoplasmosis is begun with short term follow-up imaging to see if the patient improves.

Cryptococcus is also a common brain infection in immunocompromised patients. It’s most common manifestation is enlargement of the perivascular spaces of the basal ganglia, or gelatinous pseudocysts. This typically does not have much, if any, postcontrast enhancement.

Finally, progressive multifocal leukoencephalopathy (PML) is an infection caused by reactivation of a virus (JC virus) in the brain parenchyma in the setting of immune suppression, either because of HIV or immunosuppressive medications. It is manifested by bilateral, subcortical, asymmetric white matter abnormalities without enhancement. Treatment is restoration of the immune system, but outcomes are poor.

The level of this lecture is appropriate for radiology residents, radiology fellows, and trainees in other specialties who have an interest in neuroradiology or may see patients with CNS infections.

Other videos on the intracranial infection playlist are found here.

 

Intracranial infections – 3 – Focal Infections

Focal infections are those infections of the brain which are walled off either within the brain parenchyma or in the extra-axial space, such as subdural or epidural abscess.

This lecture is the third in a series of 5 about imaging intracranial infection and covers focal brain infections. The series of videos will cover:
1) General considerations
2) Diffuse infections
3) Focal infection
4) Immunocompromised patients
5) Other considerations

Abscess in the brain, regardless of location, is characterized by hyperintensity on diffusion weighted imaging. There is often mass effect, surrounding edema, and a peripherally enhancing fluid collection. Abscess can arise from local infection, such as a surgery or sinusitis, or can occur from hematogenous spread.

Ventriculitis is a highly morbid complication of intracranial abscess, as can be found when pus spills into the ventricle. Sinus thrombosis is also a potential complication of intracranial abscess.

One key feature which separates the diffusion restriction of abscess from lymphoma is that the abnormal DWI is in the center of a peripherally enhancing collection, whereas in lymphoma it is the enhancing portion itself which is restricted.

The level of this lecture is appropriate for radiology residents, radiology fellows, and trainees in other specialties who have an interest in neuroradiology or may see patients with CNS infections.

Other videos on the intracranial infection playlist are found here.

 

Intracranial infections – 2 – Diffuse infections

Diffuse infections are those infections of the brain which affect large regions of the brain or affect the brain diffusely. This includes meningitis, encephalitis, and ventriculitis.

This lecture is the second in a series of 5 about imaging intracranial infection and covers diffuse brain infections. The series of videos will cover:
1) General considerations
2) Diffuse infections
3) Focal infection
4) Immunocompromised patients
5) Other considerations

Meningitis is infection centered in the surfaces of the brain, particularly the pia and subarachnoid space. This can be caused by bacteria, viruses, or other unusual pathogens like tuberculosis or fungi. Imaging findings include incomplete FLAIR suppression and leptomeningeal enhancement. Basilar meningitis is a special subset of meningitis affecting the spaces around the brainstem and skull base. It is special because it is more likely to be an unusual pathogen. Sarcoidosis and leptomeningeal metastases can also mimic an infectious meningitis.

Encephalitis is similar to meningitis, although it is centered in the brain parenchyma. There is a great deal of overlap between these conditions and they can often be seen together (meningoencephalitis). Compared to meningitis, encephalitis is even more likely to be viral. The medial temporal lobes are commonly involved, and when they are a diagnosis of herpes encephalitis should be considered. This encephalitis caused by HSV can be rapidly debilitating or fatal. Encephalitis can also be autoimmune or inflammatory, mimicking infection.

Finally, ventriculitis is infection within the CSF of the ventricles themselves. This is often seen by abnormal FLAIR or diffusion in the ventricles, sometimes with periventricular enhancement. This can be from a primary pathogen with sparing of the parenchyma or as a complication of meningitis or abscess. Ventriculitis also has somewhat poor prognosis.

The level of this lecture is appropriate for radiology residents, radiology fellows, and trainees in other specialties who have an interest in neuroradiology or may see patients with CNS infections.

Other videos on the intracranial infection playlist are found here.