Board Review 3 – Part 20 – Multiple choice review

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.

This final video of board review 3 is a rapid review multiple choice practice where we cover some of the non-imaging portions of the exam through 10 quick practice multiple choice questions.

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 .

Board Review 3 – Case 19

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 neck with a centrally necrotic mass in the left deep soft tissues, most likely associated with necrotic lymphadenopathy. CT images of the upper chest show tree-in-bud nodules within the upper lungs which are suspicious for infection.

The diagnosis is: mycobacterial lymphadenitis

Mycobacterial infection in the neck is most often manifested by multiple abnormal lymph nodes, often with a necrotic core. The degree of adjacent soft tissue swelling and edema is less than is typically seen with a purulent adenitis such as staphylococcus. Mycobacterium tuberculosis is the most common although there are a number of others which can cause infection, such as m. avium and m. kansasii (as in this case). The lung images are a nice clue here that the patient has a systemic infection.

Biopsy may be required to exclude malignancy, as a top differential is squamous cell carcinoma of the neck. Treatment is anti-mycobacterial drugs.

Arterial dissection is associated with a variety of conditions, including trauma, fibromuscular dysplasia, vasculitis, and connective tissue disorders.

Board Review 3 – Case 18

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 patient with Horner’s syndrome who has subtle narrowing of the extracranial internal carotid artery on the left. On T1 fat-saturated imaging, there is a crescent of methemoglobin within the medial aspect of the vessel wall.

The diagnosis is: internal carotid artery dissection

Anytime a patient, particularly a young patient, has acute onset of neurologic symptoms, arterial dissection has to be on the differential. When it is accompanied by a Horner’s syndrome, internal carotid dissection is high on the differential because the sympathetic fibers for they eye travel alongside the carotid artery.

Arterial dissection is injury to the walls of the vessel. Most often the innermost layer, the intima, is separated from the deeper layers, the media and adventitia. It can be associated with a visible flap of lifted intima in the vessel and a portion of the vessel which is not carrying blood, a false lumen. When the vessel is disrupted enough to have visible dilation, this is a pseudoaneurysm.

In this case, the MR angiogram findings are quite subtle, but the key is the T1 fat-saturated images, which show a crescent of methemoglobin in the vessel wall. Fat saturation is required to differentiate this hyperintensity from the adjacent fat in the neck, which is also hyperintense.

Arterial dissection is associated with a variety of conditions, including trauma, fibromuscular dysplasia, vasculitis, and connective tissue disorders.

Board Review 3 – Case 17

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/nJLmYJalT8s

This case shows a CT with a soft tissue density mass extending from the frontal sinus through the outer table to the prefrontal scalp soft tissues.

The diagnosis is: frontal sinus osteomyelitis/Pott’s puffy tumor

Sometimes acute sinusitis can be complicated by adjacent osteomyelitis and bone destruction, such as in this case. The most likely location for this to happen is in the frontal sinus, when the diagnosis has the moniker “Pott’s puffy tumor”.

It is important when this happens to do an MRI of the brain to check for intracranial complications, such as meningitis, dural sinus invasion, and epidural abscess. The differential diagnosis includes malignancy (metastatic disease, lymphoma, and primary sinus malignancy), mucocele, and inflammatory diseases such as granolumatosis with polyangiitis.

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.

Board Review 3 – Case 15

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 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.

Board Review 3 – Case 14

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
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.

Board Review 3 – Case 13

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 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.

Board Review 3 – Case 12

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 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.