Board Review 3 – Case 7

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.

https://youtu.be/-48w10sGN_k

This case shows expansion of the sella on a noncontrast CT, suggesting a long-standing mass. The MRI shows an underlying mass which has areas of hypointensity on T2 and intrinsic hyperintensity on T1 weighted imaging. There is minimal if any enhancement on post-contrast imaging.

The diagnosis is: pituitary adenoma (with hemorrhage)

Pituitary adenomas are common masses of the sella, with about half being non-functional and half hormone secreting. The most common hormone secreted is prolactin, followed by growth hormone. Adenomas can hemorrhage, causing variable imaging appearance.

The primary differential consideration is Rathke cleft cyst, which is more commonly midline, less likely to have blood products and septations, and may have a characteristic peripheral nodule. You can read more about differentiating adenomas and Rathke cleft cysts here.

Board Review 3 – Case 6

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.

https://youtu.be/1iD4LGFCmck

This case shows a young adult who underwent precocious puberty. There is an expansile, non-enhancing mass in the region of the hypothalamus/tuber cinereum.

The diagnosis is: hypothalamic hamartoma

Hypothalamic hamartomas are disorderly (hamartomatous) collections of neurons in the hypothalamic/suprasellar region. They most commonly occur just behind the optic chiasm and pitutitary infundibulum. Many times, they will present with unusual symptoms like early puberty (most common) or seizure (even with uncommon seizures like laughing “gelastic” seizures or crying seizure).

The differential diagnosis for masses in this region include astrocytoma, craniopharyngioma, and germinoma. The most common overall mass in this region is craniopharygioma, but these commonly enhance avidly, have a mix of solid and cystic regions, and can calcify.

Board Review 3 – Case 5

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 multiple hemorrhagic and hyperdense masses on a CT. They are predominantly supratentorial, have some edema, and are numerous.

On MRI, the regions have areas of susceptibility (dark T2 signal on GRE), surrounding edema, and enhance avidly.

The diagnosis is: metastatic disease

Intracranial metastases are extremely common and should be considered any time there are multiple masses (although 50% may be solitary). They can have hemorrhage and almost always enhance on post-contrast imaging. The most common locations are supratentorial and at the gray white junction because of the high vascularity there.

Metastases are treated with surgery or radiation. If there is oligometastatic disease (less than 10-20 lesions), stereotactic radiosurgery may be performed. Numerous lesions or leptomeningeal disease can require whole brain radiotherapy.

Board Review 3 – Case 4

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 an expansile extra-axial mass along the left frontal and parietal calvarium. On CT, it is hyperdense to the adjacent brain and it is causing mass effect and edema in the surrounding brain.On MRI, it is relatively T2 homogenous, appears to be arising outside the brain, and enhances homogenously and avidly.

The diagnosis is: meningioma

Aggressive extra-axial lesions, particularly those causing cortical destruction, have a differential including metastasis, meningioma, lymphoma, and myeloma. You may not be able to differentiate these by imaging.

Meningiomas are the most common brain tumors and most common extra-axial masses. They range in aggressiveness from WHO grade 1 (typical), grade 2 (atypical), and grade 3 (anaplastic), which is determined primarily on histologic features and not imaging criteria. Grade 1 tumors are treated with resection while grades 2 and 3 receive resection followed by radiation therapy.

Board Review 3 – Case 3

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.

https://youtu.be/NYnPSkU7Rb4

This case shows a nodular mass along the right frontal calvarium in a patient with pain. It is T2 hyperintense, T1 hypointense, and enhances avidly.

The diagnosis is: skull metastasis

Any mass in the calvarium that has associated osseous destruction is concerning. Benign masses often contain fat (are T1 hyperintense and suppress on T2 fat-saturated imaging) and rarely destroy the cortex. Pain, as was experienced by the patient in this case, is also a concerning feature.

Any patient with a concerning calvarial mass but no history of malignancy should probably be evaluated for metastatic disease. While the evaluation may vary by institution, it will most commonly consist of a whole body PET/CT or CT of the chest, abdomen, and pelvis.

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 – 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.

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.