Board Review 3 – Case 16

Posted on August 25, 2020September 3, 2020 by Brent Weinberg, MD

Board Review 3 – Case 16

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 CT of the head with scattered areas of hemorrhage centered at the gray-white matter junctions and along the corpus callosum. MRI confirms these findings, with areas of edema and susceptibility from blood products in those locations.

The diagnosis is: traumatic shear injury

In high energy traumas, areas of brain at interfaces, such as the gray-white junction, corpus callosum, and brain stem. These can be seen on CT and MRI, although MRI is more sensitive for small areas of injury. This can sometimes be referred to as diffuse axonal injury, or DAI.

Susceptibility weighted imaging (SWI) is a specialized MRI sequence tailored to detecting small areas of distortion of the magnetic field, which can be related to calcium or hemosiderin. It is a nice tool to see subtle areas of brain injury.

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Board Review 3 – Case 15

Posted on August 21, 2020 by Brent Weinberg, MD

Board Review 3 – Case 15

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

This case shows an avidly enhancing mass in the left neck which has the appearance of a tangle of vessels. These images are from a CT angiogram and the enhancement is very similar to the vascular structures, so you are likely looking at a vascular abnormality.

The diagnosis is: soft tissue arteriovenous malformation (AVM)

In this case, the abnormality has a lot of arterial enhancing components and there are associated abnormal veins, so there is a shunt between the arterial and venous structures, making this an AVM.

When looking at soft tissue vascular malformations, there is a relatively simple algorithm you can go through. If a mass has a soft tissue component, then it is a hemangioma because it has a proliferative mass component. If it has high flow components (like in this case), it is an arteriovenous malformation or AVM. If it has multiple cystic regions with fluid levels, it is a lymphatic malformation. The remaining abnormalities with slow flow vessels are venous malformations. There is a lot of overlap, with many vascular malformations having multiple components.

The treatment of these lesions is most commonly surgery, often with embolization before to reduce the amount of bleeding during resection. Sclerotherapy (or injection of a sclerotic agent through the skin) is usually not an option because these are high flow lesions and the agent will disperse to other areas in the body.

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Board Review 3 – Case 14

Posted on July 16, 2020July 14, 2020 by Brent Weinberg, MD

Board Review 3 – Case 14

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

This case shows
bilateral hippocampal and medial temporal T2/FLAIR hyperintensity with relatively little enhancement. The abnormal signal extends superiorly into the insula and subinsular white matter bilaterally.

The diagnosis is: limbic encephalitis

There is a differential diagnosis for this case which includes:

herpes encephalitis
other viral encephalitis
limbic encephalitis
infiltrative astroctyoma

Limbic encephalitis is an autoimmune condition often as part of a paraneoplastic syndrome. Patients have bilateral temporal lobe abnormalities that can be symmetric or asymmetric, and presence of enhancement is possible. Patients often have circulating antibodies, such as anti-GAD.

Herpes encephalitis usually has more enhancement and diffusion abnormality, but this is not reliable. Any patient suspected of having herpes encephalitis should be treated with antivirals (acyclovir) until herpes is ruled out to minimize the high morbidity and mortality. Other viral encephalitis can have this appearance as well, but the bilateral symmetry is highly suggestive of autoimmune limbic encephalitis.

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Board Review 3 – Case 13

Posted on July 14, 2020July 14, 2020 by Brent Weinberg, MD

Board Review 3 – Case 13

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

This case shows a left frontal hyperdense collection on a CT. The patient is on anticoagulation.

The diagnosis is: subdural hematoma

Subdural hematomas are extra-axial hemorrhages that are common in the elderly, particularly those who are on anticoagulation. They have the highest mortality of intracranial hemorrhages. Key features are an extra-axial hemorrhage that has a crescent shape that crosses sutures and tracks along dural reflections such as the falx and tentorium.

Epidural hematomas do not cross sutures because the outer layers of the dura are adherent to the bone and continuous with the periosteum. Most epidural hematomas are associated with skull fractures.

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Board Review 3 – Case 12

Posted on July 7, 2020July 7, 2020 by Brent Weinberg, MD

Board Review 3 – Case 12

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

This case is a patient who has a remote history of “meningitis”. Her imaging shows marked edema in the frontal lobes on CT, with a follow up MRI confirming significant leptomeningeal and parenchymal nodular enhancement worst in the frontal lobes. There is involvement of the right optic nerve.

With severe leptomeningeal enhancement such as this, there is a differential diagnosis which includes:

leptomeningeal carcinomatosis
unusual infections (fungi, tuberculosis, or other unusual pathogens)
sarcoidosis

The diagnosis is: neurosarcoidosis

The most common findings of sarcoidosis are leptomeningeal enhancement centered in the basal cisterns, sometimes with parenchymal nodular or perivascular enhancement. The diagnosis of neurosarcoid consists of checking a serum ACE level, performing an LP (particularly to rule out other causes), and chest imaging (including x-ray or CT). Often the easiest tissue diagnosis is through biopsy of hilar nodes.

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Board Review 3 – Case 11

Posted on May 22, 2020 by Brent Weinberg, MD

Board Review 3 – Case 11

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

This case shows a nodular lesion with calcification in the right frontal lobe. There is surrounding vasogenic edema with sparing of the cortex. CT images from higher in the brain show other areas of calcification at the gray-white junction thoughout the brain.

MR confirms these findings. There is an area of right frontal edema with a rounded enhancing structure at the gray-white junction. There is a differential diagnosis for this finding which includes infection and metastatic disease.

The diagnosis is: neurocysticercosis

Neurocysticercosis is a parasitic infection with a dual life cycle that goes through pigs and humans. When eggs excreted in human feces are ingested, it can affect the CNS. It is the most common cause of acquired seizure in endemic areas.

The treatment is anti-parasitic agents, specifically albendazole.

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Board Review 3 – Case 10

Posted on April 10, 2020April 5, 2020 by Brent Weinberg, MD

Board Review 3 – Case 10

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

This case shows a right posterior frontal tumor. There is mild mass effect with infiltrative T2 hyperintensity. On gradient imaging, there is some evidence of internal blood products or hemorrhage. Post-contrast imaging shows a multilobular and enhancing mass with irregular margins and central necrosis.

The diagnosis is: glioblastoma (GBM)

Glioblastoma, formerly known as glioblastoma multiforme, is a grade 4 primary astrocytoma and the most common primary glioma. They have extremely poor prognosis and are characterized by irregular and necrotic enhancing masses. The surrounding T2 abnormality is a result of vasogenic edema and infiltrative tumor.

With any solitary enhancing parenchymal mass, there is a differential diagnosis that should be considered, including:

glioblastoma
metastasis
lymphoma
abscess (should have bright internal DWI)
other infections

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Board Review 3 – Case 9

Posted on April 8, 2020April 5, 2020 by Brent Weinberg, MD

Board Review 3 – Case 9

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

This case shows a mass in the left cerebellopontine angle (CP angle). It is predominantly outside of the internal auditory canal (IAC), although there is extension into the canal. It is relatively homogeneous with avid post-contrast enhancement.

The diagnosis is: meningioma

Meningiomas are the most common brain tumors (although they are extra-axial). They often have a cerebrospinal fluid (CSF) cleft around them which allow you to determine that they are extra-axial. They can calcify and cause adjacent hyperostosis of the bone.

A useful approach to CP angle masses is to first consider whether it is cystic or solid. Solid masses enhance on post-contrast imaging. If they are centered in the IAC and cause expansion, it is most likely a schwannoma. If it does not cause expansion or looks centered outside the IAC, think about meningioma.

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Board Review 3 – Case 8

Posted on April 6, 2020April 5, 2020 by Brent Weinberg, MD

Board Review 3 – Case 8

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

This case shows a teenager with T2 hyperintense mass in the left posterior fossa resulting in mass effect on the 4th ventricle. On post-contrast imaging there is scattered hazy enhancement throughout portions of the mass.

The diagnosis is: pilocytic astrocytoma

Pilocytic astrocytomas are the most common brain tumors in children. They most commonly occur in the posterior fossa and are often characterized by a cystic mass with a nodular enhancing area. They are relatively benign tumors with a good 10 year survival.

When you encounter a cyst with a nodule, there is a relatively short differential diagnosis which includes:

Pilocytic astrocytoma
Ganglioglioma
Hemangioblastoma (has blood vessels/flow voids)
Plemomorphic xanthoastrocytoma – PXA

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Board Review 3 – Case 7

Posted on April 4, 2020April 5, 2020 by Brent Weinberg, MD

Board Review 3 – Case 7

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

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.

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