Author: Brent Weinberg, MD

Emergency Imaging of Brain Tumors: Astrocytomas

Posted on by Brent Weinberg, MD

Emergency Imaging of Brain Tumors: Astrocytomas

This video is the third video in an overview about the emergent approach to brain tumor imaging. This video talks about different presentations of the most common primary brain tumor type, astrocytomas, ranging from grade 2 to grade 4, showing representative emergency presentations and CT examples with emphasis on how to report the CT and next steps.

Types of astrocytomas.

Astrocytomas range from grade 2 to grade 4, with the highest grade IDH wild type tumors being glioblastomas. Some lower grade gliomas behave like higher grade tumors if they have specific molecular features.

Case 1. Grade 2 Astrocytoma.

There is a low density mass in the insula and temporal lobe with moderately well-defined margins. The differential primarily includes tumor and infection with stroke and metastatic disease less likely. The MRI shows primarily a non-enhancing mass in the medial temporal lobe and insula with a lot of expansion.

Grade 2 astrocytomas tend to be younger patients and have IDH mutation. Common locations are the frontal and temporal lobe. Enhancement, hemorrhage, and cyst formation are relatively rare.

Case 2. Grade 3 Astroctyoma.

In this case, there is a more heterogenous mass in the right basal ganglia and corona radiata. Internal areas of high density may represent some areas of calcification or hemorrhage. There is definitely more mass effect. In your differential, you would think about an intermediate grade tumor or metastatic disease. The MRI confirms that there is a more heterogeneous mass with some faint/subtle areas of enhancement centrally. This makes you think of an intermediate to higher grade tumor.

Grade 3 astrocytomas, or anaplastic astrocytomas, make but about 25% of astrocytomas. They tend to be a little less defined and are more likely to have cysts, enhancement, and hemorrhage

Case 3. Grade 4 Astrocytoma

The CT in this case shows a much more heterogeneous mass spanning both frontal lobes and involving the corpus callosum. The high density material internally likely represents hemorrhage. There is a lot of mass effect on the frontal horns bilaterally. In this case, you are definitely thinking about a high grade mass or metastatic disease. Lymphoma would be less likely. The MRI confirms what you saw on the CT, with lots of internal hemorrhage, mass effect, and extension across the corpus callosum. There is a lot of heterogeneous and ill-defined enhancement.

Grade 4 astrocytomas are either glioblastomas (if they are IDH wild type) or IDH-mutated grade 4 astrocytomas. This was a case of glioblastoma. These tumors frequently have a hemorrhage, mass effect, and heterogeneous enhancement.

Summary

In this video, we’ve seen a range of astrocytomas and how they can appear on imaging, particularly on CT. Hopefully you learned a little bit about how to form a differential on CT and give an appropriate differential.

Be sure to tune in for upcoming videos which will cover oligodendrogliomas, other common tumors, and some red flags to be alert to in the ER setting.

Thanks for tuning in. Be sure to check out the other videos on the brain tumor topic page if you want to learn more about brain tumors. Also check out the Emergency Imaging of Brain Tumors Playlist to see all the videos from this lecture.

 

Emergency Imaging of Brain Tumors: Tumor Classification

Posted on by Brent Weinberg, MD

Emergency Imaging of Brain Tumors: Tumor Classification

This video is the second video in an overview about the emergent approach to brain tumor imaging.  The first video talked about the role of imaging in an emergent setting and how to approach cases. This tells you a little bit more about the common types of tumors you might encounter and how they are classified.

Common types of brain tumors. The most common brain tumors you may encounter are primary gliomas, meningioma, metastatic disease, and lymphoma. Calvarial tumors, or those centered in the skull, have a somewhat special differential.

Primary gliomas. The primary gliomas encompass all the grade 2, 3, and 4 oligodendrogliomas and astrocytomas. In 2016, the WHO started using genetic testing more to classify these tumors, and further refined these classifications in 2021. In general, tumors are first classified by whether they have isocitrate dehydrogenase (IDH) mutation. Mutated tumors tend to be lower grade astrocytomas and oligodendrogliomas. If they have 1p19q co-deletion, they are oligodendrogliomas, and otherwise astrocytomas. IDH wild type tumors are the most aggressive and include glioblastomas. Now, there are some tumors that have genetic features that make them a lot like glioblastomas.

Pearls about primary gliomas.

  • Higher grade tumors will be characterized by mor mass effect, hemorrhage, and enhancement, although you aren’t always going to be able to tell.
  • The term “multiforme” has fallen out of use, so you can just call them glioblastomas or GBM.
  • Gliosarcomas are a special subset of tumors that have features of both gliomas and sarcomas. They are often characterized by broad dural involvement or bone involvement, but sometimes you can’t tell.
  • Oligoastrocytoma is a deprecated term no longer used. If it has 1p19q codeletion and IDH mutation, it’s an oligodendroglioma.
  • Gliomatosis cerebri is no longer it’s own diagnosis but simply a pattern of brain involvement

Pearls about other common tumors

  • Meningiomas are the most common primary intracranial tumors. If you see an extra-axial tumor, it is likely a meningioma.
  • Metastatic disease is the overall most common intracranial tumor and should be suspected in older patients and those with other malignancies
  • Lymphoma can cause solid enhancing multifocal disease
  • Calvarial tumors have a special differential including meningioma, lymphoma, myeloma, and metastatic disease

Thanks for tuning in. Be sure to check out the other videos on the brain tumor topic page if you want to learn more about brain tumors. Also check out the Emergency Imaging of Brain Tumors Playlist to see all the videos from this lecture.

Emergency Imaging of Brain Tumors: Introduction/Role of Imaging

Posted on by Brent Weinberg, MD

Emergency Imaging of Brain Tumors: Introduction/Role of Imaging

Hi everyone! In this video, we’re going to talk about the emergent imaging of brain tumors, particularly as it applies to a general approach when you might see patients like this coming through the emergency department. We’ll have a special emphasis on computed tomography throughout this lecture. This is the ideal lecture for someone who practices neuroradiology and sees some patients with brain tumors, but isn’t exactly a brain tumor expert.

Role of imaging brain tumors in emergencies. There are 2 main tools for imaging brain tumors, CT and MRI. CT is the screening tool for initial identification of a potential mass and then evaluating complications such as hemorrhage, edema, mass effect, hydrocephalus, and herniation. However, MRI is the mainstay of tumor evaluation used for evaluation of tumor type, tumor worsening, and tumor details.

MRI. MRI is used to make a more specific initial diagnosis, for pre-treatment planning, and for follow-up after surgery and treatment. It will almost always have FLAIR, diffusion weighted imaging (DWI), and pre- and post-contrast T1 imaging. A few other tools are used for troubleshooting, such as perfusion and functional MRI (fMRI).

FLAIR. This is a key sequence for evaluating a mix of edema and infiltrative tumor. It is the best comparison for CT

Pre- and post-contrast T1. Areas of post-contrast enhancement show areas of breakdown of the blood brain barrier. This can happen when the tumor itself has disrupted it or when there has been tissue damage from radiation therapy. More aggressive tumors have more enhancement

Role of emergent imaging. When a patient comes to the ER, if a patient doesn’t have a known tumor, you might use it to identify a potential tumor, give a practical differential, and recommend next steps. In patients with tumors, you might use it to identify urgent complications. The role of emergent imaging is not to give an exact diagnosis or assess tumor progression.

Summary. In this video, we have covered some of the basics of imaging patients with brain tumors in emergent situations, including when CT and MRI are most appropriate.

This is the first lecture in this series about imaging brain tumors in the emergent setting. Hopefully you learned a little bit about the role of different imaging types. The next lectures are going to discuss some additional topics in detail, including how to classify these tumors, how to interpret common imaging studies, and how to avoid red flags.

Thanks for tuning in. Be sure to check out the other videos on the brain tumor topic page if you want to learn more about brain tumors.

Emergency Imaging of Brain Tumors – Playlist

Posted on by Brent Weinberg, MD

Emergency Imaging of Brain Tumors

This playlist covers the imaging of brain tumors in an emergency setting, with particular emphasis on how a general radiologist might approach these cases and how to formulate a smart differential on CT.

You can learn more about brain tumors on the brain tumor topic page. Also, please check out our full channel on Youtube.

5 ways to improve your brain aneurysm search pattern

Posted on by Brent Weinberg, MD

5 ways to improve your brain aneurysm search pattern

In this video, I walk you through 5 quick tips that you might use to improve your brain aneurysm search pattern on CT angiograms of the brain. This is a longer version of a lecture I put together with Everlight Radiology, so be sure to check them out.

Have a standard search pattern. When I’m looking at a CTA of the head, I do the anterior circulation first and then move from right to left, then over to the posterior circulation.

Know the common aneurysm locations. The most common aneurysm location is the anterior communicating artery (35%) followed by the carotid terminus (30%) and middle cerebral artery (20%). Posterior circulation aneurysms are relatively uncommon (10%) but it’s important to look there as well. Try to use these tips on the sample case.

Use reformats and 3-D imaging. These supplemental tools can help you improve your sensitivity. Multiplanar reformats are thin slices that are displayed in the other planes, while maximum intensity projections (or MIPs) show you the brightest pixel in a thicker slice. Volume renderings are a nice way to make measurements and increase your sensitivity.

Using the MIPs can definitely make you more sensitive. The axial MIPS are great to see the MCAs, the sagittal MIPs are great to see the carotid terminus and ACAs, and the coronal MIPs are great to see the posterior circulation and MCAs again.

Follow the blood. This is my favorite tip. The location of the blood on the non-contrast CT is one of the best clues about where your aneurysm is going to be. You need to check that area very closely.

 

 

 

Recognize the mimics. There are some things which can mimic aneurysmal subarachnoid hemorrhage, but some features may help you know that it is less likely to be from an aneurysm. Atypical location, an unusual history, or unusual patient demographics can clue you in that it might be a different cause. Be sure to think about hypertensive hemorrhage, venous infarct, tumor (glioma, metastasis, or cavernous malformation), and benign perimesencephalic hemorrhage.

Summary. These 5 quick tips can help you be better at understanding aneurysms and being better and finding them.

If you haven’t already, be sure to check out the vascular imaging course and sample cases that you can scroll through.

See all of the search pattern videos on the Search Pattern Playlist.

Radiology professor tries AI writing tool to create material for website

Posted on by Brent Weinberg, MD

Radiology professor tries AI writing tool to create material for website

Wondering where all the junk on the internet comes from? Apparently it is written by computers using artificial intelligence! Well, at least that’s what the folks over at jasper.ai would like for you to believe. According to this company, they are using AI to help you write materials for your blog or website to drive traffic your direction. At the very least, they promise they will make it easier for you.

People have been promising that computers were going to take over radiology for at least the past decade, and as far as I can tell there has been very little progress. However, most of this is about image interpretation and this is the first time I’ve seen a product claim that it can do writing for you.

As the owner of learnneuroradiology.com and producer of a lot of educational content, I was wondering what this would mean for someone who creates highly specialized content like myself. I figured this might be halfway decent for a generic interest blog or website, but I didn’t think it would be very good for subspecialized material like radiology and specifically neuroradiology.  

Introduction to the product

I started by taking a look at their introduction video, where they make a lot of claims about how much faster they can create content and show you a brief example. Like all promotional material, it definitely makes big promises, including that they have analyzed 10% of the internet. There are testimonials and everything. I feel like this tells us a lot about the internet that most of it is being written by a bot.

It took a little bit to set up a trial. I had to enter the name of my website, some billing information (including a credit card number), and what kind of content I was creating. The full product starts at $49 / month but there is a free trial for 5 days. That’s what I’m taking. Once I finished, I was able to see the full dashboard.

Generic article about Brain MRI

I started with a generic article about Brain MRI to see how it would do with some more general content. After entering some basic information, I got started pretty quickly. It required me to start writing the article before it created some content, but surprisingly it generated some half-way relevant, if overly generic material. With a little bit of guidance and a few clicks, I had created a decent general interest article. My initial impressions were that it was doing ok. It did a pretty decent job on a general article. I give it a “B to B+”.

More specific article about glioblastoma

Now it’s time to give it something a little harder. Glioblastoma. I expected it to perform worse, but it had some surprisingly decent comments about the imaging features and could even differentiate between imaging modalities, like computed tomography, magnetic resonance imaging. It could fill in rudimentary although sometimes wrong information about the differential diagnosis and prognosis. I’m not going to lie, this is exceeding my expectations.

Technical article about white matter abnormalities

Finally, I tried an article a little bit more technical about white matter abnormalities. Of all the articles, this one did the worst, but it was still fairly relevant. It was able to come up with some differential diagnosis for white matter lesions and relevant diseases. It did provide a little bit more irrelevant or wrong content than the other articles.

It did make me a little sad that we don’t have more report generation tools that are radiology specific. I feel like a similar tool trained on radiology reports with radiology diagnoses could actually go a long way towards helping me generate differential diagnoses on challenging cases. I’m looking forward to having more tools like this in the future but I don’t feel like this is quite ready for primetime right now, even for writing a website.

Tune in next time for additional interesting content and radiology teaching material! Thanks for checking out the site!

Summary

So what are my final recommendations? I wouldn’t use it for my site, but it is capable of generating some half-way useful content. I expected to be able to make fun of it more, but it exceeded my applications. What is my overall impression: I wouldn’t throw it in the trash. I can imagine it is pretty useful for a generic interest site, but for more specialized applications it does get a little unraveled. It becomes a little repetitive, and I’m worried that it is actually just regurgitating content from other sites. There is a “plagiarism checker” but I was unable to use it because it required an additional fee that I didn’t want to pay.

“What is my overall impression: I wouldn’t throw it in the trash.”

 

It did make me a little sad that we don’t have more report generation tools that are radiology specific. I feel like a similar tool trained on radiology reports with radiology diagnoses could actually go a long way towards helping me generate differential diagnoses on challenging cases. I’m looking forward to having more tools like this in the future but I don’t feel like this is quite ready for primetime right now, even for writing a website.

Tune in next time for additional interesting content and radiology teaching material! Thanks for checking out the site!

Neuroradiology Board Review – Brain Tumors – Case 20 and Summary

Posted on by Brent Weinberg, MD

Neuroradiology Board Review – Brain Tumors – Case 20 – Summary

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.

This video has both the final case of the series and a quick review summary!

Case 20

In this case, you are starting with an immunocompromised patient with HIV. Initial CT images show a hyperdense mass in the left basal ganglia with a lot of surrounding edema. This is helpful, because a few things are known for being hyperdense on CT.

MRI images confirm a mass in the basal ganglia. It is somewhat T2 hypointense with well-defined margins and surrounding edema. On postcontrast images, it has peripheral enhancement but central non-enhancement compatible with necrosis.

The differential diagnosis for a solitary enhancing parenchymal mass is different in an immunocompromised patient (or someone on immune suppressing agents. In an immune normal patient, the top diagnoses are

  • metastatic disease
  • high grade glioma
  • lymphoma

On the other hand in an immunocompromised patient the order of these diagnoses shifts to include:

  • lymphoma
  • infection
  • metastatic disease
  • high grade glioma

As you can see, lymphoma and infection jump to the top in an immunocompromised patient.

The diagnosis is: CNS lymphoma

CNS lymphoma can occur when associated with systemic lymphoma or primarily in the CNS, as in this case. This is most commonly a diffuse large B-cell lymphoma. It is more common in immune compromised patients. It often occurs in the basal ganglia and periventricular white matter and can often be multifocal. Lymphoma is one of the rare diseases which is T2 hypointense, so you should think about it if you see a T2 hypointense mass.

In immunocompetent patients, lymphoma most commonly has solid enhancement. However, in immunocompromised patients it is much more likely to show central necrosis, as in this case. Also, in an immunocompromised patient, it can be hard to differentiate lymphoma from infection, particularly toxoplasmosis. The two most common ways to try to differentiate this are to start a trial of toxoplasmosis therapy for a few weeks and see if the lesions improve and to perform a thallium-201 chloride nuclear medicine scan. Lymphoma has thallium uptake, while toxoplasmosis does not.

Summary

In this board review lecture, you’ve seen a lot of different tumors and how they manifest in different situations. In many cases, you can’t make a definitive diagnosis but you should always be able to come up with a reasonable differential diagnosis. It’s also helpful to know some of the basics about treatment and prognostic factors.

There are two key strategies that I hope can help you get a few additional points, the approach to CP angle masses and the approach to cortical tumors.

Cerebellopontine angle masses

As we’ve seen in some of the other cases, cerebellopontine angle masses can be solid or cystic. Solid masses that involve the IAC and expand it are likely schwannomas, while others outside the IAC are likely meningiomas. Arachnoid cysts and epidermoids are the most common cystic masses which are differentiated by DWI (which is bright in ependymomas.

Cortical tumors

Several of the cases in this series dealt with cortical temporal tumors. Ill-defined masses that are larger are more likely to be low grade gliomas (oligodendrogliomas and astrocytomas). Completely non-enhancing bubbly masses favor DNET. A little nodular enhancement favors ganglioglioma, while pleomorphic xanthoastrocytoma (PXA) can be more avidly enhancing and irregular.

Neuroradiology Board Review – Brain Tumors – Case 19

Posted on by Brent Weinberg, MD

Neuroradiology Board Review – Brain Tumors – Case 19

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 of a patient with diplopia (double vision) starts with a CT through the orbits. You can see there is a well-defined mass at the right orbital apex.

On MRI, you can see the lesion again is well-defined with well defined margins and is hyperintense on T2. On T1, the lesion is isointense to muscle on pre-contrast and then demonstrates heterogeneous enhancement on postcontrast. It looks like the lesion is enhancing more on the coronal image compared to the axial image.

The diagnosis is: orbital venous vascular malformation

Orbital venous vascular malformations are sometimes referred to as hemangiomas, although this term is falling out of favor because it is not neoplastic (unlike the neoplastic infantile and neonatal orbital hemangiomas). These are relatively benign lesions that can cause visual problems secondary to mass effect, but it’s relatively uncommon for them to enlarge.

One characteristic finding of orbital venous malformations is progressive enhancement on delayed images. On early images, it might be enhancing a little bit but if you have more delayed images, you might see more enhancement. If you don’t have more than one plane of contrast, you can bring them back and image them again 15-30 minutes later and it should fill in.

The primary differential considerations for orbital masses are sarcoidosis, idiopathic or IgG4 related orbital disease, metastatic disease, and lymphoma. When it is this well defined and has the characteristic delayed enhancement, the diagnosis is relatively certain.

Neuroradiology Board Review – Brain Tumors – Case 18

Posted on by Brent Weinberg, MD

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

Posted on by Brent Weinberg, MD

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.