Brain imaging course – Unknown case 7 and conclusion

This video is the 7th and final unknown case that goes with the brain imaging capstone course. At the end, we wrap up what we’ve learned.

If you want to follow along, you can find all the images for the case at the brain capstone website.

Introduction

37 year-old man presenting with the worst headache of his life

Interactive review – noncontrast CT

In this case, there is a noncontrast axial and coronal CT. On the axial images, you see some subarachnoid blood in the prepontine cistern and 4th ventricle which increases as you go superior. There is subarachnoid blood in the sylvian fissures and interhemispheric fissure. There is also enlargement of the ventricles, or hydrocephalus. The coronal CT confirms these findings.

Interactive review –CT angiogram (CTA)

There is an axial CT angiogram and we need to look for causes of subarachnoid hemorrhage. It’s important to follow a search pattern so you don’t miss important findings or fall victim to satisfaction of search. The identifies a potential aneurysm of the anterior communicating artery (A-comm), where there is a 4 mm rightward directed outpouching. The coronal images confirm the finding. We want to make sure to look at our vertebral and basilar arteries too though so we don’t miss any findings.

Imaging recap

A few key images show the hemorrhage centered in the basal cisterns with anterior involvement. Select images from the CTA show the aneurysm of the ACA.

Your first question is what is the cause of the subarachnoid hemorrhage? In this case it is a cerebral aneurysm rupture.

Angiographic images show the outpouching before and after it is coiled through endovascular treatment.

Your second question is what is a common complication of subarachnoid hemorrhage? Vasospasm is a very common complication which occurs 4-10 days after the onset of hemorrhage and can result in narrowing of vessels and possible ischemia.

Diagnosis – Subarachnoid hemorrhage and aneurysm rupture

This is a case of subarachnoid hemorrhage from aneurysm rupture. Hypertension, drug use, trauma, and family history are all risk factors. The pattern of aneurysm can help you identify where the aneurysm might be. Some locations are more common for aneurysms. 90% of aneurysms are anterior, with common locations being the Acomm, ICA terminus, and MCA. Other common locations are the basilar tip and PICA.

Recap

What have we learned? We learned the value of different imaging modalities, including CT, CTA, and MRI, and when to choose them. CT is a screening exam to identify severe pathology, with MRI used to get a more detailed examination of the brain parenchyma.

Thanks for tuning in to all the cases as part of the brain course. There are a total of 7 cases you can review on your own at the website and explanations will be posted here.

See all of the brain course videos on the brain course playlist, or go back to the brain capstone course page.

 

Brain imaging course – Unknown case 6

This video is the 6th unknown case that goes with the brain imaging capstone course.

If you want to follow along, you can find all the images for the case at the brain capstone website.

Introduction

69 year-old-female with h/o autoimmune hepatitis on immunosuppression, admitted for hyponatremia. Hospital course complicated by vision changes and leukocytosis.

Interactive review – MRI

This MRI includes diffusion weighted imaging (DWI), apparent diffusion coefficient (ADC), FLAIR, T2, T1 pre-contrast, and T1 postcontrast. The FLAIR image shows a lesion which is isointense to gray matter centrally with hyperintense edema around the margin. The T2 has a unique feature which helps point to this diagnosis, which is a relatively T2 dark surrounding rim. On pre-contrast T1, it is dark in the center with a rim of edema which is not too dark. On postcontrast it is enhancing around the periphery with central necrosis.  

On the diffusion images you see a rounded hyperintense structure in the right occipital and parietal lobe. It is extremely bright centrally, and is also quite dark on ADC. This proves that there is low water diffusion in the center of the lesion.

Case summary

This case is summarized by a few key findings: lightbulb bright diffusion, dark ADC, and a central rim of enhancement with central necrosis.

Question 6

How would you describe the restricted diffusion pattern, and what is it concerning for? The pattern is centrally reduced diffusion, which is concerning for pus.

Diagnosis – Cerebral abscess

This is a case of a cerebral abscess, in this case from aspergillus. This patient was immunocompromised and had symptoms of infection. Common symptoms for presentation include seizure, altered mental status, or focal neurologic symptoms. Key imaging features are the central hypodensity on CT, a centrally enhancing region with necrosis centrally, and reduced diffusion in the center. The T2 hypointense rim is a characteristic of abscess which isn’t seen on many other disease.

See all of the brain course videos on the brain course playlist, or go back to the brain capstone course page.

 

Brain imaging course – Unknown case 5

This video is the 5th unknown case that goes with the brain imaging capstone course.

If you want to follow along, you can find all the images for the case at the brain capstone website.

Introduction

51 year-old-female presents with left sided weakness and numbness

Interactive review – CT

This case features a CT with a brain window on the left and a bone window on the right. As you scroll up, you start to note that the right lateral ventricle is a little compressed and there is loss of the normal sulci on the right. If you window it really tightly, you can start to see the outlines of a mass along the parietal convexity. In this case, we want to get an MRI so we can better evaluate it.

Interactive review – MRI

The MRI includes diffusion weighted imaging, FLAIR, T2, and pre- and post-contrast T1 weighted imaging. On diffusion, the mass is faintly hyperintense but pretty homogeneous with compression of the brain away from the mass. Similarly, on FLAIR, the mass is pretty homogeneous and has a large contact with the dura and adjacent calvarium. The T2 is particularly helpful because you see a thin cleft of CSF around the mass (a CSF cleft). You also see a little bit of a radial spoke type pattern radiating out from the calvarium where the bone is abnormal. On pre-contrast T1, the mass is pretty isointense to slightly hypointense to the adjacent gray matter. On postcontrast, you see homogeneous and avid enhancement and again are able to make out the CSF cleft. The coronal postcontrast images confirm the findings you saw on axial imaging

Interactive question 5

Is this lesion intra-axial or extra-axial? It is extra-axial

How do you know? You have a thin CSF cleft, compression of the brain away from the mass, and a thin dural tail.

CT explanation

Some select images from the CT are shown here, where you can see the subtle mass and bony erosion. There are some examples from a CT angiogram showing displacement of the dural vessels away from the mass. An additional representative example shows vessels radiating out from the central portion of the mass.

MRI explanation

Select images from the MRI show key images highlighting the CSF cleft sign, the dural tails, and the avidly enhancing extra-axial mass.

Diagnosis – Meningioma

This is a case of a meningioma. These usually occur in older patients > 40 years old and present with symptoms of brain compression or increased intracranial pressure. Meningiomas range from grade 1-3. The treatment of meningioma is usually surgical resection, sometimes with radiation afterwards. If they are in delicate locations or the patient has health problems making surgery less desirable, you can treat them with radiation alone.

See all of the brain course videos on the brain course playlist, or go back to the brain capstone course page.

 

Brain imaging course – Unknown case 4

This video is the 4th unknown case that goes with the brain imaging capstone course. If you want to follow along, you can find all the images for the case at the brain capstone page.

Introduction

65 year-old male with possible ground level fall found to be altered. On Coumadin for DVT.

Interactive review

This case features a CT showing a hyperdense hemorrhage in the extra-axial space. You first see it in the left middle cranial fossa and going along the temporal convexity all the way up to over both cerebral hemispheres. There is significant mass effect with uncal unherniation and complete effacement of the basal cisterns. There complete compression of the left lateral ventricle with entrapment of the right lateral ventricle.

Another finding that you can see is hypodensity in the left PCA distribution, which suggests that there is an infarction. This is from mass effect on or stretching of the PCA.

Interactive question 4a

What additional complications do you see on this case? From the explanation, you can see that you have all the complications, including midline shift, uncal herniation, infarct, and ventricular entrapment.

Interactive question 4b

What territory is the infarct in? The left PCA distribution

Diagnosis and Summary

This is a case of acute subdural hematoma. This can occur in patients who are older, who have falls, or who are on anticoagulation. There are a lot of potential complications that you can see in this case, such as ventricular entrapment and hernation.

You can tell the difference in subdural and epidural hematoma most of the time. Subdural hematomas are crescent shaped, cross sutures, and cross along dural reflections. Epidural hematomas are almost always associated with fractures and high energy traumas.

Thanks for tuning in to this case. There are a total of 7 cases you can review on your own at the website and explanations will be posted here.

See all of the brain course videos on the brain course playlist, or go back to the brain capstone course page. Be sure to check back in for additional videos in the future or check out the website at https://www.learnneuroradiology.com

 

Brain imaging course – Unknown case 3

This video is the 3rd unknown case that goes with the brain imaging capstone course. If you want to follow along, you can find all the images for the case at the brain capstone page.

Introduction

62 year-old male with new onset of left sided weakness, left facial droop and right eye pain

Interactive review

In this case, there is a CT showing a large hypderdense hemorrhage in the right parietal lobe. There is a lot of surrounding edema and mass effect, with effacement of the sulci, herniation from right to left, and complete effacement of the right lateral ventricle. The coronal and sagittal view confirm these findings.

This hemorrhage appears to be in the brain parenchyma, and the most common cause of a parenchymal hemorrhage is hypertension. You can also get hemorrhages from other causes such as cerebral amyloid angiopathy.

Case findings summary

A summary of the imaging findings is reviewed here.

Interactive question 3a

Vascular imaging in this patient is negative, what is the next step? The next step in this patient is neurosurgical consultation, as the patient is at high risk of herniation and death from the hemorrhage.

Companion case

This shows a similar case of hypertensive hemorrhage, only in this case there is extension of the hemorrhage into the ventricles, or intraventricular extension.

Interactive question 3b

What is the major potential complication in this companion case? Because of the intraventricular extension, the patient is at high risk of hydrocephalus, either from outflow obstruction or communicating hydrocephalus.

Diagnosis and Summary

This is a case of hypertensive hemorrhage. These mostly occur in older patients, with common locations being the thalamus, basal ganglia, pons, and cerebellum. You can get them in the cerebral hemispheres as in this case, although it is less common and you might think of other causes such as venous infarct or cerebral amyloid angiopathy. These cases are extremely common and one of the most common things we see in neuroradiology.

Thanks for tuning in to this case. There are a total of 7 cases you can review on your own at the website and explanations will be posted here.

See all of the brain course videos on the brain course playlist, or go back to the brain capstone course page. Be sure to check back in for additional videos in the future or check out the website at https://www.learnneuroradiology.com

 

Brain Bites – Central Neurocytoma

Welcome to our new series, Brain Bites, where we are going to be making short videos featuring other physicians and learners explaining neuroradiology concepts in short, easily digestible bites. Hopefully these videos will give you some quick points so that you can become more effective at evaluating brain and spine imaging.

Today’s video is focused on central neurocytoma and is presented by Stefani Yates, a medical student at Morehouse School of Medicine.

Central neurocytoma is a heterogeneous mass which usually occurs in the frontal horn of the lateral ventricle along the septum pellucidum, or the then septation that separates the lateral ventricles. These masses are usually heterogeneous on T2, isointense or similar to gray matter on T1, and enhance heterogeneously and avidly. In this case you can see a mass in the left frontal horn along the septum pellucidum.

Patients can be asymptomatic or they may present with nonspecific features such as a headache, as this patient did. Treatment is usually surgical resection, or they can be conservatively managed.

The differential diagnosis includes:

  • Ependymoma – an enhancing mass more common in the 4th ventricle
  • Subependymoma – a ventricular mass which usually does not enhance
  • Meningioma – a ventricular mass most common in the occipital horn which has more homogeneous enhancement.

So, if you see an intraventricular mass along the septum pellucidum, keep in mind central neurocytoma. Thanks for watching today!

Check out the full Brain Bites page or the Brain Bites YouTube Playlist for more short learning content.

Brain imaging course – Unknown case 2

This video is the 2nd unknown case that goes with the brain imaging capstone course. If you want to follow along, you can find all the images for the case at the brain capstone page.

Introduction

60 year-old man with personality changes and lack of motivation with flat affect for 1-2 months

Interactive review

In this case, there is an MRI showing a mass in the bilateral frontal lobes, but more in the right frontal lobe. It crosses the corpus callosum. It is markedly enlarged with FLAIR and T2 hyperintensity, abnormal DWI suggesting high cellularity, and a few areas of hemorrhage on SWI.

On post-contrast imaging, you see a mass with peripheral enhancement and central necrosis (a ring enhancing mass). There are multiple additional areas of enhancement (multifocal enhancement). Findings are very concerning for a high grade tumor, such as a glioblastoma.

Case findings summary

Here you can see screenshots of the findings which we saw in the interactive case review.

Interactive question

What makes this tumor appear high grade? Central necrosis, thick nodular rind of enhancement, multifocal enhancement, restricted diffusion, crosses midline (corpus callosum) 

Diagnosis and Summary

This is a case of glioblastoma. These are high grade tumors of the brain which have a very poor prognosis, and are one of the few aggressive lesions which will cross from one side of the brain to the other. This is a classic appearance of GBM.

Thanks for tuning in to this case. There are a total of 7 cases you can review on your own at the website and explanations will be posted here.

See all of the brain course videos on the brain course playlist, or go back to the brain capstone course page.

Brain imaging course – Unknown case 1

This video is the 1st unknown case that goes with the brain imaging capstone course. If you want to follow along, you can find all the images for the case at the brain capstone page.

History

83-year-old female with h/o hypertension presents with altered mental status, slurred speech, left hemiplegia and right sided gaze

Interactive review

In this case, there is a CT showing an area of hypodensity and loss of gray-white differentiation in the right cerebral hemisphere. There is a corresponding area of vascular occlusion at the right carotid terminus on the CT angiogram

On the MRI, you can see a large area of DWI abnormality in the left MCA distribution confirmed on the ADC imaging. There is corresponding FLAIR abnormality. These are all findings of an MCA distribution infarct.

Case findings summary

Here you can see screenshots of the findings which we saw in the interactive case review.

Interactive questions

Test your knowledge learned during the rest of the course and on this case.

Summary

Thanks for tuning in to this case. There are a total of 7 cases you can review on your own at the website and explanations will be posted here.

See all of the brain course videos on the brain course playlist, or go back to the brain capstone course page.

Brain imaging course – 5 – Common imaging pathology

This video is the fifth in a series of a brain imaging course. In this video, we review some of the most common imaging pathologies that you’ll encounter, particularly in hospitalized patients.

Check out the entire course if you haven’t already.

Introduction

This video is going to focus on some of the most common pathologies that you’ll encounter in brain imaging. We’ll review common CT and MRI findings that you’ll see on those cases. The most common pathologies a beginner should be familiar with are stroke, hemorrhage, hydrocephalus, tumor, and infection.

Stroke

Stroke is death of tissue due to occlusion of blood flow, and more specifically, oxygen delivery, to the brain. This is most commonly caused by arterial obstruction or less commonly venous obstruction. Most of the time we start imaging with CT, where you may see loss of gray-white differentiation in a vascular territory. Vascular imaging and MRI are excellent supplements for evaluation stroke. Be sure to look out for complications such as stroke and hemorrhagic conversion. The example shows you an example of a left MCA infarct in a patient with endocarditis. Over time, stroke gets more hypodense and more well-defined. Cortical necrosis is a specific deposition of blood in the cortex which is a benign finding and should not be called hemorrhagic conversion. Stroke almost always corresponds to a vascular territory, so it is valuable to know the territory distributions of the ACA, MCA, and PCA.

Hemorrhage

Hemorrhage is the development of acute blood products, particularly in the brain. It is characterized by where it located, and the location is an excellent clue to what is the most common cause. Acute blood starts hyperdense to the surrounding brain parenchyma and will gradually decrease over time.

Subarachnoid hemorrhage is one of the most common types of hemorrhage that you may encounter. It is commonly caused by trauma or aneurysm rupture. If you see subarachnoid hemorrhage, you should get a CT angiogram to look for the cause of hemorrhage.

Extra-axial hemorrhages include subdural hematoma and epidural hematoma. Subdural hematomas can be spontaneous, associated with anticoagulation, or associated with trauma. They cross sutures and spread along dural reflections. Epidural hematomas are almost always associated with skull fractures.

Parenchymal hemorrhages occur in the brain itself. The most common cause is hypertensive hemorrhage, which occurs most commonly in central locations like the basal ganglia, thalamus, pons, and cerebellum. Peripheral hemorrhages may be caused by other things like venous infarct, cerebral amyloid angiopathy, or tumors.

Hydrocephalus

Hydrocephalus is enlargement of the ventricles that can be due either to decreased resorption of CSF or blockage of CSF flow. There are two main types, communicating, which is an issue with CSF resorption, or non-communcating/obstructing. The example shows you a case of hydrocephalus from an obstructive mass at the foramen of Monro. Increase in size and ventricle contour are your clues. Edema around the ventricles is a clue that hydrocephalus may be acute.

Tumor

Tumors are space occupying lesions or masses within the brain. They can be located within the brain parenchyma (intra-axial) or outside the brain (extra-axial). The most common intra-axial tumors are metastases and primary tumors, while the most common extra-axial tumor is a meningioma. If lesions are single, it’s more likely to be a primary tumor or solitary metastasis. Multiple lesions may be lymphoma or metastatic disease. The example shows you a peripherally enhancing and centrally necrotic high grade glioma in the left temporal lobe.

Infection

Infection is characterized by location. Meningitis is infection of the CSF space or meninges. Encephalitis is infection of the brain parenchyma. Walled off masslike infection is called abscess. Patients who are immunocompromised, such as patients with HIV or patients on immune suppression for organ transplants or autoimmune conditions are more at risk.

The example shows a patient with a single focal lesion with diffusion hyperintensity in the parietal lobe. Many times you can’t tell the cause of infection just from imaging, but will need correlation with CSF labs, systemic labs, and other history to know the organism. Sometimes you’ll even need a biopsy.

Summary

Thanks for tuning in to the video. Hopefully you are now familiar with some of the most common brain pathology and are ready to check out some cases on your own. The next 7 videos will walk you through independent review of cases you can review on the website.

See all of the brain course videos on the brain course playlist, or go back to the brain capstone course page.

Brain imaging course – 4 – Reviewing a normal case

This video is the fourth in a series from brain imaging course. In this video, we go through a normal brain imaging case in a patient who is normal. We first go through a head CT and then the patient’s brain MRI.

Check out the entire course if you haven’t already.

Introduction

In this video, we are going to go through a normal case together. I’ll show you how to apply what you’ve learned in the other videos on your own. Be aware of the strength of having a structured pattern when looking at the images so you can use them effectively.

Normal Head CT

A normal head CT search pattern begins on the brain images. I go from top to bottom, looking for symmetry, gray-white differentiation, and normal underlying structures. I also first review the brain window, then the bone window, then any reformats.

Click here to get the Head CT

On the brain window, I start at the bottom, reviewing normal structures for symmetry, including normal CSF structures. White matter should be a little less dense than gray matter because it has higher fat/myelin content. You should see some gray-white differentiation in the basal ganglia structures. As you reach the vertex, you should see symmetric sulcation, and the brain should be coated with gray matter in all locations. If you lose gray-white differentiation, that can be a sign of stroke.

CT bone window

On the bone window, I also start at the bottom, looking for any fractures in the skull base, any destructive lesions, and that the cortex is maintained everywhere. I will often come back and look at soft tissues using a soft tissue window, including the orbits, sinuses, and facial soft tissues.

CT reformats

There are two reformats provided with this case. The coronal reformat is great to look at the convexity, the floor of the anterior and middle cranial fossa, and the posterior fossa (cerebellum). The sagittal reformat is similar with the additional advantage of being able to see some midline structures like the corpus callosum really well.

Normal Brain MRI

Reviewing a normal MRI is similar, but you need to make multiple passes because of the different information that is found on different sequences. Each sequence has its own advantages, so use them to your benefit.

Click here to get the Brain MRI

Diffusion weighted imaging

DWI is great for seeing restricted water movement. Strokes and abscesses are usually hyperintense. You can use the ADC (not shown) just to make sure it is not bright from T2 effects only (“T2 shine through”).

FLAIR

FLAIR is a real workhorse of clinical imaging. You can recognize FLAIR because the white matter is darker than gray matter. Pathology will be bright because it has excess water. CSF is suppressed on FLAIR imaging, which makes pathology easier to see.

GRE

Gradient recalled echo (GRE) T2 imaging is a blood sensitive sequence which is good to see iron, hemosiderin, blood, and air. These things will be dark on GRE. Some normal structures like blood vessels and iron containing nuclei can be darker normally.

T2

T2 is like FLAIR in that pathology tends to be bright (hyperintense). However, the fluid is not suppressed. This gives you a little bit better view of fluid filled structures like the ventricles but you see pathology in the brain parenchyma worse.

Pre-contrast T1

T1 has the opposite contrast of T2, in that white matter is hyperintense to gray matter. This is a key trick for identifying what kind of imaging you are looking at. T1 precontrast images are great for seeing normal anatomical structures as well as the normal marrow. They are also important to compare pre-contrast

Post-contrast T1

The post-contrast T1 is a key sequence because it will identify areas of breakdown of the blood brain barrier. Pathology like tumors, infection, and demyelination, will often enhance. Some normal structures like vessels, the pituitary, and choroid plexus enhance normally.

Conclusion and recap

Thanks for tuning in to the video. Hopefully now you have developed your own basic approach to brain imaging that you can use on the test cases. On the next video, we’ll review some of the most common brain pathology. The final videos will provide some individual cases you can go through on your own.

See all of the brain course videos on the brain course playlist, or go back to the brain capstone course page.