Neuroradiology Board Review – Brain Tumors – Case 4
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 images from an MRI through the level of the pons. There is a mass in the left cerebellopontine angle (CP angle). It is causing mass effect on the pons. On postcontrast imaging, you can see that it is avidly enhancing with a few central areas of non-enhancement. A key to this case is identifying where the mass is centered. Does it look like it’s outside the IAC or centered in and expanding the IAC?
The diagnosis is: vestibular schwannoma
Vestibular schwannomas are extraaxial masses arising from the vestibular nerve (8th cranial nerve) either as they pass through the cerebellopontine cistern or in the internal auditory canal. They were previously called acoustic neuromas, but it is preferable to call them vestibular schwannomas given our current understanding of them. A key imaging feature is that they expand the internal auditory canal (IAC).
When approaching a cerebellopontine angle mass, it is useful to take a two step approach. First, determine if you think it is mostly solid and has enhancing components. If so, then think about schwannoma or meningioma as your top two differential considerations. If it is centered in the IAC and causes IAC enhancement, it’s probably a schwannoma. Meningiomas in this location occur but are more likely to have only minimal extension into the IAC without expansion.
This patient also had hydrocephalus from compression of the 4th ventricular outflow. Remember that masses in the posterior fossa can cause hydrocephalus due to mass effect.
Neuroradiology Board Review – Brain Tumors – Case 3
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 single image from a head CT as well as some MRI images at the same level. There is a dominant mass in the left parietal lobe which has some internal blood products. There is surrounding edema, but not much enhancement as most of the T1 hyperintensity is intrinsic (present on the pre-contrast exam) from blood products/methemoglobin. Upon closer inspection, there is also a smaller enhancing nodule in the adjacent cerebral hemisphere.
The diagnosis is: metastatic disease
Metastases to the brain are common manifestations of malignancies elsewhere in the body. The most common diseases to cause brain metastases are the same as the most common systemic cancers, including lung cancer, breast cancer, and melanoma. When brain metastases have hemorrhage, you might think about melanoma, renal cancer, and thyroid cancer (among others).
The most common locations for brain metastases are in the cerebral hemispheres and cerebellum. About 50% of brain metastases are solitary, so don’t be fooled if you see only a single lesion. It can still be a metastasis.
The differential diagnosis for most metastatic lesions includes infection and high grade glioma. Demyelinating disease can also sometimes have a similar appearance.
Neuroradiology Board Review – Brain Tumors – Case 2
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 of the brain with a pretty well-defined, expansile mass in the inferior aspects of the right parietal lobe with some extension into the adjacent frontal and temporal lobes. It is markedly T2 hyperintense, but somewhat less intense centrally on FLAIR. On pre- and post-contrast imaging, this shows that the tumor is predominantly non-enhancing, although there is a thin rim of enhancement around the anterior margin.
The diagnosis is: anaplastic astrocytoma (grade 3)
Anaplastic astrocytomas are grade 3 astrocytomas that are most commonly IDH mutated. They tend to have slightly more mass effect and enhancement than grade 2 tumors but do not have the necrosis and avid enhancement of grade 4 tumors most of the time. 1p19q codeletion is absent in these tumors because if present these would be oligodendrogliomas.
The T2 mismatch sign is a relatively recently described imaging finding of IDH mutated astrocytomas. When a portion of the tumor is very bright on T2 but suppresses on FLAIR, this is a pretty specific sign for IDH-mutation. This fact could appear on an ABR exam, especially the CAQ exam.
Neuroradiology Board Review – Brain Tumors – Case 1
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 of the brain with a highly heterogeneous, expansile mass in the right frontal lobe extending into the corpus callosum. There is a large degree of mass effect. On postcontrast imaging, there is a rim of avid enhancement with central necrosis.
The diagnosis is: glioblastoma
Glioblastomas, or GBMs, are high grade primary glial tumors and the most common primary brain tumor. The definition has recently been changed to only include IDH-wild type tumors, with IDH-mutated tumors now called grade 4 astrocytomas. These tumors have a very poor prognosis despite maximal therapy. They are characterized by avidly enhancing, necrotic masses with surrounding T2 hyperintensity that is a mix of tumor and edema.
Molecular markers are increasingly important in determining the prognosis of brain tumors. IDH-mutated tumors have a better prognosis, as do tumors with MGMT methylation. 1p19q codeletion is the characteristic mutation associated with oligodendrogliomas. These facts are fair game on ABR exams.
Welcome to this new board review series for 2022. In this series, we are going to focus on all things brain tumors that you might need to know as you prepare for the American Board of Radiology exams. While these videos are geared towards those taking the ABR core exam, they would also be useful for people taking the certifying or certificate of added qualification (CAQ) in neuroradiology exam.
There are going to be a total of 20 cases covering the most common brain tumors you might encounter in neuroradiology practice. Each one will have a series of images followed by 1 or 2 questions you can answer on your own as you follow along. Then there will be an explanation of the answers before you can move on.
By doing this series, hopefully you can quickly cover everything you need to know about brain tumors.
If you have not yet seen the other board review videos, I recommend you check out the categorized board review page.
A few lesions within the spinal canal are predominantly cystic or nonenhancing. They are almost always intradural extramedullary. The three most common entities are arachnoid cysts, dermoid cysts, and neuroenteric cysts. A contrast enhanced myelogram can often give you a little bit more information about what the entity is by determining if it fills with contrast.
Case 1. Arachnoid cyst. Arachnoid cysts in the spine are somewhat uncommon but will have the same characteristics as CSF on all images. They may often be identified only by their deflection of the spinal cord and mass effect. Their main differential is arachnoid webs or adhesions which cause similar mass effect on the spinal cord. On myelography, they often fill with contrast but more slowly than the surrounding CSF.
Case 2. Dermoid. Dermal inclusion cysts, or dermoids, are complex lesions made out of tissue from more than one embryonal layer. Their characteristic feature is internal fat contents. Like intracranial dermoids, they can rupture and cause a chemical meningitis. Their appearance overlap with lipomas but they are more likely to have complex features
Case 3. Neuroenteric cysts. Neuroenteric cysts are relatively simple cystic lesions which often occur ventral to the brainstem or spinal cord. They often are similar to but not exactly like CSF, and can be T1 hyperintense. They are indolent lesions but can cause mass effect. They do not fill on myelography.
Cyst summary. These are three of the most common cystic lesions. They are best differentiated by whether they communicate with the thecal sac (arachoid cysts), have complex or fatty features (dermoids), or are ventral to the cord and slightly differ from CSF (neuroenteric cysts).
Summary of spine tumors by location. Overall, when thinking about spine tumor, you should take a location-based approach. If you haven’t seen the introduction video yet, then definitely check it out. When divided by intramedullary, intradural extramedullary, and extradural, this can help you decide what type of lesion you are dealing with. Overall, always remember that the spine is an extension of the central nervous system, and consider imaging the brain because that may help you hone your differential diagnosis.
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 spine tumors.
Lesions outside the thecal sac are categorized as extradural lesions. Remember that everything that isn’t in the thecal sac is extradural, including discs, bones, meninges, nerves, and blood vessels. Anything that can occur in the surrounding areas can have extradural components. Look for lesions that have mass effect on the dura and deflect both the dura and the thecal sac to the side. Many of these lesions will require a biopsy as they have a differential diagnosis on imaging. CT and diffusion weighted imaging are useful adjunct tools that can help you refine your diagnosis.
The rest of this lecture consists of a mix of case presentations of different extradural lesions with tips on how to refine your differential diagnosis.
Case 1 – Disc extrusion. These are one of the most common extradural pathologies, particularly in patients with a history of degenerative disc disease. They tend to be contiguous with the disc and follow the disc in signal. Don’t be alarmed if they have enhancement, particularly if the enhancement pattern is peripheral. These can be confused with schwannomas and meningiomas.
Case 2 – Lymphoma. Lymphoma can involve the bones at any spinal level and can result in pathologic fracture. Anytime you see involvement of the pedicles and posterior elements you should worry about pathologic fracture, particularly if there is soft tissue or epidural involvement and enhancement. When the bone is involved, think about performing a CT to see the pattern and extent of bone destruction. This lesion has a mixed lytic and sclerotic appearance with bone destruction and was ultimately proven to be lymphoma.
CT pattern of different bone lesions. When you have a bone lesion, the trabecular pattern and pattern of bone destruction can be helpful. Lesions such as benign vascular malformations (hemangiomas) have a classic trabecular or corduroy pattern, while Paget’s disease is characterized by cortical thickening.
Case 3 – Osteosarcoma. Bone sarcomas are aggressive lesions that have bone destruction and can have soft tissue components. Their characteristic finding is matrix deposition which is best seen on CT. Osteosarcomas tend to have fluffy cloudlike matrix (osteoid) while chondrosarcomas have arcs and rings with interrupted calcification (chondroid). This was a case of osteosarcoma.
Benign versus pathologic fractures. It can be challenging to differentiate fractures from bone insufficiency or trauma from those with an underlying lesion (pathologic fracture). Pathologic fractures are more likely to have bowing of the posterior cortex, a surrounding soft tissue mass, and abnormality on DWI. Looking for lesions elsewhere in the body can be a clue that it is metastatic disease, lymphoma, or myeloma. Sometimes these diseases can also have diffuse involvement of all of the marrow which can manifest as low T1 intensity throughout all the vertebral bodies.
Epidural tumor. Ventral epidural tumor can form a curtain or drape appearance because the dorsal dura is tacked down to the vertebral body at the midline. When it becomes more circumferential, it can extent completely around the thecal sac and extent both cranially and caudally.
Case 4 – Chordoma. Chordoma’s are aggressive tumors arising from notochordal remnant cells that can occur anywhere along the spinal axis. They are most common in the sacrum > clivus > remaining spine. Their characteristic appearance is a lytic lesion with bone destruction and marked T2 hyperintensity.
Enhancement pattern of extradural lesions. The enhancement pattern can help differentiate extradural lesions which may look similar. Tumors tend to have solid enhancement, abscess has peripheral enhancement, and a hematoma may have little or no enhancement.
Case 5 – Spinal dural arteriovenous fistula (dural AVF). These lesions have a classic presentation in older gentlemen with progressive myelopathy and are often missed. On MRI, they usually have edema and possibly enhancement in the cord, but the key finding is squiggly vascular enhancement along the margins of the cord. The pathology is from an abnormal connection between a vein and artery in the nerve root sleeve and can be treated endovascularly or with surgery.
Case 6 – Angiolipoma. These are fat containing lesions most common in the thoracic spine along the dorsal epidural space. They will have fat density on CT and can slowly increase in size, causing myelopathy.
Summary. There are a lot of things that can cause extradural masses, but they most commonly arise from the surrounding structures like discs and bones. Hopefully this video will help you refine your differential in the future.
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 spine tumors.
Lesions that occur within the thecal sac are categorized as intradural extramedullary lesions. The vast majority of these lesions are tumors. The most common are schwannomas (and other nerve sheath tumors) and meningiomas, but there are others that include ependymoma, metastatic disease, and lymphoma. Also remember that the intradural extramedullary space contains cerebrospinal fluid (CSF), so any process that diffusely affects CSF can affect this space.
Peripheral nerve sheath tumors are a group of benign and malignant nerve tumors including schwannomas and neurofibromas. These can expand the neural foramen and usually have well defined margins. Schwannomas tend to enhance a lot while neurofibromas enhance less. Sarcoidosis is another common granulomatous disease that can affect the cord. The most common appearance is T2 abnormality within the cord with some enhancement. Enhancement is often along the surface of the cord.
Neurofibromatosis is a genetic syndrome with two types, type 1 and type 2. NF type 1 is characterized by multiple plexiform (involving more than one adjacent nerve root) neurofibromas. If neurofibromas increase in size rapidly, have necrosis, or cause pain, that can be a sign of malignant degeneration. NF type 2 is characterized by multiple masses including schwannomas, meningiomas, or ependymomas. NF type 2 is sometimes called MISME syndrome.
Schwannomas are probably the most common intradural extramedullary lesions. They are well defined lesions with avid enhancement. They often have central non-enhancement or cystic degeneration, but calcification or hemorrhage are less common.
Case 1 – Meningioma. Meningiomas are well demarcated intradural lesions which occur along the dura and deflect the spinal cord. They enhance avidly and usually don’t have necrosis. They frequently calcify, which you may appreciate more on CT. If they are more elongated and plaquelike they may be referred to as “en plaque” menigiomas. They can cross the dura and have components outside the dura as well.
Case 2 – Myxopapillary ependymoma. Myxopapillary ependymomas are relatively common tumors that occur around the conus and cauda equina. They usually enhance avidly. Necrosis or hemorrhage are more common than in schwannomas. They were previously grade 1 tumors but have been upgraded to grade 2 because they frequently recur.
Leptomeningeal metastases are a consideration anytime you see multiple intradural nodules. In adults, these are most commonly from the most common tumors such as melanoma, lung, and breat cancer. Lymphoma can also occur along the cauda equina. In pediatric patients you should also think about intracranial tumors that spread in the CSF, like medulloblastoma, pineal
Case 3 – Paraganglioma. Spinal paragangliomas are rare spine tumors that have a lot of abnormal surrounding vessels and are prone to hemorrhage. Think about them anytime you see an enhancing tumor in the spine with a lot of flow voids. The other thing you might think about is a hemangioblastoma, but they are more likely to be cystic.
Case 4 – Lipoma. Fat containing lesions along the conus are common and can be lipomas or dermoids. Clues are fat-suppression of FS images, chemical shift artifact, and fat density on CT. If it is thin and linear along the filum terminale, it is likely a benign fatty filum terminale.
Summary. Intradural extramedullary lesions are among the most common spinal lesions and it is important to have a clear differential when you see them.
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 spine tumors.
There are a wide range of lesions occurring in the spinal cord which can mimic tumors. This includes vascular lesions, inflammatory/demyelinating disease, sarcoid, and CSF flow abnormalities. This video takes a look at some of the range of possibilities.
Cord infarcts are areas of disruption of blood flow. Primary characteristics are abnormal diffusion imaging and acute onset. Often patients have other pathology such as recent aortic surgery or aortic dissection.
Sarcoidosis is another common granulomatous disease that can affect the cord. The most common appearance is T2 abnormality within the cord with some enhancement. Enhancement is often along the surface of the cord.
Neuromyelitis optica is a demyelinating disease characterized by long segment myelitis, often in the cervical cord. It is associated with optic neuritis and abnormal anti-aquaporin antibodies.
Radiation myelopathy can happen in patients that have had radiation to the cord or surrounding region. Knowing the history is important. Radiation necrosis frequently will have less mass effect than other tumors and will respond to steroids.
Syrinx or presyrinx can occur in the setting of CSF flow obstruction. This can commonly occur with conditions such as Chiari malformation or due to a large disc bulge. A cystic syrinx can cause mass effect and mimic tumor but will rarely have enhancement.
Arachnoid adhesions or webs are special situations of CSF obstruction where an adhesion in the CSF space deflects the cord contour. Due to deflection, CSF flow within the central canal can be disrupted and cause cyst-like expansion mimicking a tumor. The characteristic finding is the “scalpel sign” where the cord contour takes on the appearance of a surgical scalpel.
Summary. History is extremely important in evaluating potential spine tumors as additional history may inform you that a lesion isn’t a tumor at all.
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 spine tumors.
In this lecture in the spine tumor series, we take a look at intramedullary lesions within the spinal cord. These are lesions that are within the dura and the substance of the spinal cord.
The most common intramedullary tumors are primary tumors of the cord itself, most commonly ependymomas and astrocytomas. Other things such as hemangioblastoma and cavernous malformations can also happen in the spinal cord. For the rest of this lecture, we take a look at a few case based examples of intramedullary tumors.
Case 1 – Astrocytoma. Astrocytomas are the second most common cord tumors and the most common tumors in young adults. They frequently have enhancement. Low grade tumors (grade 2) are the most common although glioblastomas/high grade tumors can also occur.
Case 2 – Ependymoma. Ependymomas are the most common cord tumors and the most common tumors in adults. They often have a cystic appearance with a well marginated nodular lesion. Hemorrhage and a “cystic cap” are common. Ependymomas are associated with neurofibromatosis type 2.
How to differentiate astrocytomas from ependymoma. Ependymomas are usually older patients with shorter segment lesions and well-defined margins, while astrocytomas are younger patients with more ill-defined margins.
Cord glioblastoma. Intramedullary glioblastoma has the same appearance as glioblastoma and appears like a high-grade lesion with mass effect, ill-defined margins, and necrosis.
Case 3 – Hemangioblastoma. Hemangioblastomas are common cord tumors and are associated with Von Hippel Lindau (VHL) syndrome. 1/3 are associated with the syndrome while 2/3 are spontaneous. Tumors often appear as a cyst with an enhancing nodule. You may see flow voids similar to those you see in the brain, although they are often harder to see. Patients with VHL may also have brain hemangioblastomas, endolymphatic sac tumors, and other systemic tumors (such as renal tumors).
Case 4 – Cavernous malformation. Cavernous malformations, sometimes referred to as cavernomas, can occur in the spinal cord. They have a similar appearance to cavernous malformations in the brain, often with a rim of siderosis and central T1 and T2 hyperintensity. Little to no enhancement is common.
Causes of hematomyelia (blood in the spinal cord). The differential for hematomyelia includes coagulation disorder, vascular malformations, anticoagulation medications, trauma, or cord tumor with repeated hemorrhage.
Take-home points.
The spinal cord is an extension of the brain and affected by similar pathologies
Tumors are the most common pathology. Astrocytomas (< 20 years old) and ependymomas (> 20 years old)
Other tumors can also affect the spinal cord
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 spine tumors.
