Neuroradiology Board Review – Brain Tumors – Case 18

Neuroradiology brain tumor 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 starts with 2 axial images from a CT through the posterior fossa followed by MRI images through the same region. There is a heterogeneous lesion to the left of the midline along the left foramen of Lushka. On postcontrast images, it is pretty avidly enhancing. The enhancing margins are pretty well defined and it looks like it is wholly in the ventricle.

The diagnosis is: ependymoma

Ependymomas are enhancing intraventricular tumors arising from the ependymal lining. They are commonly enhancing and conform to the ventricles and the ventricular outflow tract, which results in their description of “toothpaste” like lesions. In adults, they most commonly occur in the 4th ventricle although in pediatric patients they can occur elsewhere.

When in the posterior fossa, your main differential is choroid plexus papilloma/tumor. If you can’t tell that it’s an intraventricular lesion it can be harder because the differential diagnosis also include metastatic disease and possibly medulloblastoma. If you see a lesion that looks similar but doesn’t enhance very much, think about it’s sister lesion subependymoma.

Neuroradiology Board Review – Brain Tumors – Case 17

Neuroradiology brain tumor 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.

In this case, we have an MRI showing a FLAIR and T2 hyperintense mass in the left insula with relatively ill-defined margins. On SWI, there are some areas of susceptibility that probably represent calcification, although blood products could look similar. Postcontrast images demonstrate little or no contrast enhancement.

1:33 The diagnosis is: oligodendroglioma

Oligodendrogliomas are gliomas which are now defined by the characteristic genetic features of IDH mutation and 1p19q codeletion (loss of portions of both chromosomes 1 and 19). They can be WHO grade 2 (as in this case) or grade 3 (anaplastic oligodendroglioma). Theoretically, these lesions never degrade into WHO grade 4 lesions although the grade 3 lesions can be quite aggressive. In general, oligodendrogliomas have a better prognosis than their sister gliomas, astrocytomas. They respond better to radiation and have better overall survival.

Oligodendrogliomas are treated with a combination of resection and chemoradiotherapy.

The susceptibility seen within the tumor on this case represents areas of calcification. Oligodendrogliomas are one of the main considerations if you see an expansile tumor with calcification.

 

Neuroradiology Board Review – Brain Tumors – Case 16

Neuroradiology brain tumor 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 20 year-old with seizures. MRI shows a lesion in the medial temporal lobe along the tentorium. It is relatively well circumscribed with a cystic portion as well as an enhancing nodule. There is not much mass effect.

The diagnosis is: ganglioglioma

Gangliogliomas are low grade tumors often found in the temporal lobes of patients with seizures. They are mixed in their cell origin, containing both components of glial and neuronal cells. Along with pilocytic astroctyoma, PXA, and hemangioblastoma, they are one of the tumors in the differential for a tumor with a cyst and a nodule. They can be impossible to differentiate from DNET, but if you see enhancement it is more likely to be a ganglioglioma. Gangliogliomas are the most common neoplastic cause of epilepsy.

When you see a minimally enhancing cortical tumor, you should have a relatively short differential which includes:

First consider whether they are ill-defined or well-marginated. If ill-defined, the differential includes astrocytoma or oligodendroglioma. If well-marginated, then consider whether there is enhancement. If no enhancement, DNET is most likely. If there is a small amount of nodular enhancement, favor ganglioglioma, as in this case.

 

In a testing situation, if a small and minimally enhancing cortical tumor enhances a little bit, choose ganglioglioma. If you don’t seen enhancement, choose DNET. PXAs tend to be much more heterogeneous and irregular.

If you use a structured approach to these tumors, you can fall back on it if you aren’t really sure what you are looking at. With these relatively simple rules, you can be sure to get the most points on your exams AND give the most meaningful differential diagnosis.

Full Brain Tumor Board Review Playlist on Youtube

Neuroradiology Board Review – Brain Tumors – Case 15

Neuroradiology brain tumor 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.

As we start this case, we see a brain and a bone window from a CT through the posterior fossa. It is a little bit hard to see because it is a midline abnormality. The sagittal and coronal reformats are helpful in identifying where the lesion is located.

MRI is a little bit easier to see the lesion, but only a little. There is a well-demarcated lesion along the inferior aspect of the 4th ventricle. There is calfication, which you could see both on CT and GRE sequences from MRI. On post-contrast imaging, there is little, if any enhancement.

The diagnosis is: subependymoma

Subependymomas are relatively benign tumors arising from the walls of the ventricles. In contrast to most other intraventricular tumors, they often do not have much enhancement. The most common locations are in the 4th ventricle and lateral ventricles. Many times they are incidental but they can cause symptoms related to hydrocephalus.

Your differential diagnosis for intraventricular lesions includes meningioma, ependymoma (more enhancing), choroid plexus tumors (also more enhancing), and other tumors such as subependymal giant cell tumors (SEGT, often seen in patients with tuberous sclerosi).

Some tumor types have characteristic histologies that you should be familiar with for the test. Ependymomas are associated with perivascular pseudorosettes, while other tumors such as glioblastoma have their own histologic keywords (pseudopallisading necrosis, microvascular proliferation). These are pretty low yield to study but if you see them it’s good to be familiar with them.

Neuroradiology Board Review – Brain Tumors – Case 14

Neuroradiology brain tumor 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 MRI with a mass in the left parietal region near the midline. It is pretty well circumscribed and is probably extra-axial. It is homogeneously enhancing on postcontrast, and both T2 and T1 images demonstrate significant vascular flow voids suggesting that this is a very vascular lesion.

The diagnosis is: solitary fibrous tumor

Solitary fibrous tumors of the CNS (previously known as hemangiopericytomas) are similar in histology to fibrous tumors elsewhere in the body, such as the pleura. These were originally thought to be related to meningiomas, but their genetics has proven this to be false. However, the imaging features are similar to aggressive meningiomas. They are most often extra-axial, have avid enhancement, and broad dural attachments. It is common to have flow voids showing a high degree of vascularity.

Like meningiomas, these can be highly vascular lesions with much of their blood supply coming from external carotid branches. This angiogram shows the high degree of vascularity. It can be favorable to embolize as many of these vessels as possible prior to surgical resection to minimize bleeding.

Remember that the nomenclature has changed but you still may run into the term hemangiopericytoma. It’s something that should be on your differential if you see something that looks like an aggressive meningioma.

Neuroradiology Board Review – Brain Tumors – Case 13

Neuroradiology brain tumor 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 presents an MRI in a patient with symptoms that sound like partial seizures. There is a pretty subtle abnormality in the medial right temporal lobe. The abnormality is a little bit hard to see, but there is some FLAIR and T2 hyperintensity in the right medial temporal lobe and amygdala. You see it best on the coronal images.

The diagnosis is: dysembryoplastic neuroepithelial tumor, or DNET

DNETs are benign and relatively slow growing tumors often in the gray matter of the medial temporal lobe. They rarely have much enhancement or hemorrhage. They are often described as “bubbly” or “soap bubble” lesions. They are often associated with seizures. Resection or ablation can be curative.

When you see a minimally enhancing cortical tumor, you should have a relatively short differential which includes:

First consider whether they are ill-defined or well-marginated. If ill-defined, the differential includes astrocytoma or oligodendroglioma. If well-marginated, then consider whether there is enhancement. If no enhancement, DNET is most likely. If there is a small amount of nodular enhancement, favor ganglioglioma. As in this case, PXAs tend to have more enhancement in a more irregular pattern.

 

In a testing situation, if a small and minimally enhancing cortical tumor enhances a little bit, choose ganglioglioma. If you don’t seen enhancement, choose DNET. PXAs tend to be much more heterogeneous and irregular.

If you use a structured approach to these tumors, you can fall back on it if you aren’t really sure what you are looking at. With these relatively simple rules, you can be sure to get the most points on your exams AND give the most meaningful differential diagnosis.

Full Brain Tumor Board Review Playlist on Youtube

Neuroradiology Board Review – Brain Tumors – Case 12

Neuroradiology brain tumor 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.

In this case, you first see a CT with a hyperdense mass anterior to the frontal horn of the left lateral ventricle. On MRI, you see a somewhat nodular appearing mass with a rim of hypointensity on T2. Centrally, there are areas of T1 and T2 hyperintensity. On postcontrast, there is minimal if any enhancement, best seen on the 3D postcontrast images.

The diagnosis is: cavernous malformation

Cavernous malformations are benign collections of disorganized blood vessels. They have previous names, including cavernoma and cavernous hemangioma, but these have fallen out of favor because these lesions do not have a proliferative component.

On imaging, these are characterized as “popcorn” like masses with a rim of hemosiderin. They usually have areas of T1 and T2 hyperintensity centrally. Classically they are described as non-enhancing, but in my experience it is relatively common (maybe 25-30% of the time), probably because of the increase in thin-slice 3D imaging. Cavernous malformations can be isolated (about 2/3 of cases) or familial (the remaining 1/3). Familial cavernous malformation are associated with mutations in the KRIT or CCM genes. There is a relatively low annual risk of hemorrhage from these lesions (about 0.25-0.75% per year for single lesions or 1% per year per lesion for familial cavernous malformations).

Cavernous malformations can mimic hemorrhage, particularly if the history is trauma. CT sometimes has calcification, which can be a nice clue. Otherwise, the lack of symptoms and lack of edema can help you. Sometimes, you may need an MRI or a delayed CT follow-up (24-48 hours later) to show that it is stable and prove it is not a hemorrhage.

Often cavernous malformations have an associated developmental venous anomaly adjacent to them. This is a venous structure which has a tree-like branching pattern and otherwise resembles a normal vein. These can sometimes be large and confuse people into thinking it is an arteriovenous malformation, but there is no shunting.

 

Full Brain Tumor Board Review Playlist on Youtube

Neuroradiology Board Review – Brain Tumors – Case 11

Neuroradiology brain tumor 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 MRI with mass along the left cerebral convexity. The mass is pretty homogeneous on all sequences. On pre- and post-contrast T1, there is pretty avid enhancement.

Anytime you are looking at a brain mass, you should try to decide if it is arising within the brain parenchyma (intraaxial) or outside the brain parenchyma (extraaxial). The main clue that a mass is extra-axial is if it displaces the adjacent brain and you can see a cleft of CSF between the tumor and the adjacent brain. The differential diagnosis for an extra-axial mass (meningioma, lymphoma, metastatic disease) is very different from the differential diagnosis for an intra-axial mass (glioma, metastasis, demyelinating disease, infection).

The diagnosis is: meningioma

Meningiomas are the most common brain tumors overall and the most common extra-axial tumors. They are usually homogeneous and can have avid enhancement. Nice clues are if you see a cleft of CSF between the mass and the brain and if you have dural tails (small enhancing components extending along the dura adjacent to the mass). Sometimes meningiomas have a radiating spoke pattern extending out from the calvarium.

Meningiomas can be WHO grade 1, 2, or 3. All grades are treated with resection. Since Grade 2 and 3 have a higher risk of recurrence, they are often treated with radiation after resection.

The ABR loves to add anatomy questions as a follow-up. In this video, I’ve shown you the hand knob, which is an “inverted omega” shaped gyrus in the precentral gyrus. This is a good clue that you are in front of the central sulcus and is a reliable way to identify the central sulcus.

Full Brain Tumor Board Review Playlist on Youtube

Board Review Cases – All topics

This playlist is a collection of all the board review style cases on the site. All the board review style cases on the site in one place! These cases are geared towards preparation for the radiology resident ABR core exam, although similar material is used for the ABR certifying exam general and neuroradiology sections as well as neuroradiology CAQ.

The format of this playlist 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.

If you prefer, check out the full “Neuroradiology board review cases – All” playlist on YouTube.

 

Neuroradiology Board Review – Brain Tumors – Case 10

Neuroradiology brain tumor 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 you a posterior fossa mass in a child. It his relatively homogeneously T2 hyperintense with relatively avid central enhancement on post-contrast imaging. On ADC, it is relatively dark centrally. A sagittal FLAIR image looks like it confirms that the mass is arising from the cerebellar wall of the ventricle and is displacing the ventricle anteriorly.

Anytime you have a posterior fossa mass in a child, you should be able to list a differential diagnosis, which includes:

  • pilocytic astroctyoma
  • ependymoma
  • medulloblastoma
  • atypical teratoid/rhabdoid tumor (ATRT)

These are listed in order of decreasing ADC values, because the tumors at the bottom are more cellular and have more tightly packed cells that will be bright on DWI and dark on ADC.

The diagnosis is: medulloblastoma

Medulloblastomas are aggressive tumors in children most commonly found in the posterior fossa. They can be differentiated from other tumors in these age groups by their aggressive appearance and lower ADC values. They arise from the walls of the 4th ventricle or cerebellar hemispheres. There are 4 types (WNT, SHH, group 3, and group 4), but for most radiologists this is beyond the expected knowledge. Genetic features will ultimately guide the prognosis and treatment.

The main differential diagnosis in a child with a lesion such as this is ATRT. I recommend an age based approach to making your differential diagnosis. Because ATRT patients usually are around 6 months old, if a patient is less than 2 years old, choose ATRT. If older, choose medulloblastoma. This will not always be true but is probably true > 95% of the time.

Full Brain Tumor Board Review Playlist on Youtube