Spine tumors 1 – Introduction to a location-based approach
Spine tumors can be a challenging topic for a neuroradiologist because we deal less with tumors in the spinal cord and spinal canal. However, there is a relatively simple approach that can hep you hone your differential diagnosis. This involves taking a location-based approach which divides the spinal canal into 3 main regions.
Intramedullary – in the spinal cord
Extramedullary intradural – in the thecal sac (within the dura) but outside the spinal cord
Extradural – outside the dura
Then, you can formulate your differential based on the normal structures in those regions. You can’t always tell the exactly location of a lesion, but you can use the displacement of normal structures to help you try to decide. Then you know how to guide your differential.
By the end of this video you will be able to name the three main compartments of the spine for classification of tumors. The subsequent videos will help walk you through the more specific locations using case examples and potential mimics.
Special thanks to Dr. Michael Hoch for helping with this lecture and Dr. John Loh for handing down the drawing over the generations!
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.
Other videos on the spine tumor playlist are found here.
Spine tumors can be a challenging topic for a neuroradiologist because we deal less with tumors in the spinal cord and spinal canal. However, there is a relatively simple approach that can hep you hone your differential diagnosis. This involves taking a location-based approach which divides the spinal canal into 3 main regions. This series of videos shows the general approach as well as specifics about making a differential diagnosis in each of these locations.
Be sure to check back often as more videos are added that cover your favorite neuroradiology exams, or check out our full channel on Youtube.
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Spine tumors 1 – Introduction to a location-based approach
In this video, Dr. Bailey reviews the most important things you should know about the skull base anatomy with an emphasis on CT imaging. With this quick video, in just a few minutes you can learn about the most important skull base foramina when reviewing CT.
Optic canal. Contains the optic nerve, optic sheath, and ophthalmic artery.
Superior orbital fissure. Multiple cranial nerves to the orbit (III, IV, V1, and VI) as well as the superior ophthalmic vein.
Inferior orbital fissure. Contains the infraorbital artery, nerve, and vein. It’s a little harder to identify because it is smaller and more inferior.
Pterygopalatine fossa (PPF) and foramen rotundum. The PPF is a fat containing structure which contains the V2 segment of the trigeminal nerve. The foramen rotundum carries the V2 segment through the wall of the sphenoid sinus into the PPF.
Foramen ovale. Contains the mandibular nerve (V3), the accessory meningeal artery, the lesser petrosal nerve, and an emissary vein connecting the cavernous sinus to the pterygoid plexus.
Foramen spinosum. Contains the middle meningeal artery and vein and an meningeal branch of the mandibular nerve. It is the smaller foramen lateral to the foramen ovale.
Vidian canal. Contains the vidian nerve, artery and vein. It is best seen on coronal along the inferior margin of the sphenoid sinus at the level of the pterygoid plates.
Hypoglossal canal. Contains the hypoglossal canal. Best seen on the axial medial to the jugular foramen. Can also be seen on the coronal below the beak of the “eagle” sometimes described.
Foramen magnum. A large opening in the occipital bone containing the brain stem and upper spinal cord, vertebral arteries.
This video describes the soft tissue spaces of the head and neck, including common normal anatomy and structures found in each region as well as potential pathology that can commonly arise there. By knowing the spaces, you can be more prepared to determine what diseases might occur there and formulate a better differential diagnosis.
Masticator space. Contains the muscles of mastication, the mandible, branches of the trigeminal nerve, lymph nodes, and minor salivary glands.
Parotid space. Contains deep and superficial portions of the parotid gland, branches of the facial nerve, lymph nodes, the retromandibular vein, and the external carotid artery and its branches.
Carotid space. Contains the carotid sheath, internal jugular vein, cranial nerves IX-VI, sympathetic nervous system branches, and lymph nodes.
Parapharyngeal space. Predominantly composed of fat, with minor salivary glands and lymph nodes. Most useful for how it is displaced (medially if it is in the masticator space, carotid space, or parotid space, or laterally if it is a mucosal lesion)
Retropharyngeal space. Contains, fat, lymph nodes, and minor salivary glands.
Perivertebral/vertebral space. Contains muscles, the vertebral bodies, fat, blood vessels, and nerve roots.
Infrahyoid visceral space. Contains the thyroid and parathyroid gland, the esophagus, and the trachea. Vessels and nerves are also found here.
Today, Dr. Bailey is back with a video about her approach to head and neck anatomy using landmarks. With this quick video, in about 5 minutes you can learn to quickly differentiate the important anatomical subsites of the head and neck on computed tomography.
Nasal cavity versus the nasopharynx. The nasal cavity and nasopharynx are both above the hard palate up to the cribriform plate. The nasopharynx begins just behind the posterior margin of the hard palate
Oral cavity vs oropharynx. Similarly, the oral cavity includes the tissue below the hard palate and anterior to its posterior margin, while the oropharynx includes what is posterior to the margin of the hard palate.
Floor of the mouth. The floor of the mouth is predominantly made of muscular structures, including the genioglossus, hyoglossus, and mylohyoid.
Hypopharynx. The hypopharynx consists of the pyriform sinuses, the lateral and posterior pharyngeal walls, and the posterior surfaces of the larynx extending to the cervical esophagus.
Supraglottic larynx. The supraglottic larynx includes everything from the tip of the epiglottis down to the laryngeal ventricle.
Larynx-glottis. The glottis includes the larynx and true vocal cords, including the anterior and posterior commissures.
Larynx-subglottis. The subglottis extends from the inferior aspect of the true vocal cords to the cricoid cartilage. Below the cricoid cartilage is the trachea.
Cervical Lymph Node Stations – a landmark approach
In this quick video, Dr. Bailey walks us through a quick overview of 6 of the common cervical nodal stations in the neck. Each lymph node in the neck is assigned one of these 6 levels based on their relationship with normal anatomic structures in the neck. These stations are important in communicating with other physicians which abnormal nodes we are talking about.
By using only these 8 landmarks, you can feel confident that you are properly identifying the right nodal locations:
In this second video about the temporal bone, Dr. Katie Bailey from the University of South Florida goes over some common pathology of the temporal bone. If you haven’t seen the first video and want to learn more about a general approach to reviewing temporal bone CT, go back and check out the first video.
The overview puts this video in the context of the outside-in approach reviewed in the first video. You can think about which diseases are most prevalent in each compartment based on location. A general differential of infection, inflammation, and tumor is a good place to start.
Otitis externa – a common pathology characterized by thickening of the mucosa of the external auditory canal. It may be accompanied by fluid in the mastoids and middle ear.
Malignant otitis externa – a variant of otitis externa in which you have destruction of the adjacent bone. You can also have soft tissue or intracranial abscesses as a complication.
External auditory canal neoplasm – soft tissue in the external auditory canal with adjacent bone destruction. The imaging appearance overlaps with malignant otitis.
Otitis media – characterized by fluid within the middle ear and around the ossicles. Most commonly in the mesotympanum and hypotympanum. There is often associated fluid in the mastoid air cells (otomastoiditis).
Cholesteatoma – a soft tissue mass often originating in Prussak’s space which results in blunting of the scutum and bone erosion.
Ossicular disruption – the ossicular chain can be disrupted, most often in trauma. The most common disruption is the malleoincudal joint, or loss of the “ice cream cone”.
Aberrant ICA – as a variant, the internal carotid artery can be located too medially, where it will lack a complete bony covering in the foramen lacerum. This can lead to complications of mastoid surgery and is important not to miss.
Dehiscent jugular bulb – the jugular vein should also have a bony covering between it and the middle ear.
Tympanicum paraganglioma (glomus tympanicum) – a vascular tumor of the middle ear starting at the cochlear promontory.
Labyrinthitis ossificans – sclerosis of the cochlea or semicircular canals. The cochlea or semicircular canals may be narrowed or sclerotic, usually from prior infection.
Semicircular canal dehiscence – loss of bone adjacent to the semicircular canal. This most commonly occurs along the superior aspect of the superior semicircular canal.
Otosclerosis – abnormal bone most commonly in the fissula ante fenestrum, manifested by lucent bone where it should be dense cortical bone.
Facial nerve – the facial nerve should have a smooth bony covering around it. If you see loss of bone, you should think about a hemangioma or a facial nerve schwannoma, two tumors that frequently occur in this area.
Today we have a special guest, Dr. Katie Bailey from the University of South Florida who is presenting her approach to the temporal bone. Special thanks to her for this great video, and hopefully we will be having a lot of great new content from her in the future. This video will be part 1 of 2 in overviewing a starting approach to reviewing the temporal bone.
In this video, she goes through her structure approach to CT of the temporal bone. This approach is based upon an outside-in strategy, where you first look at the external ear, the middle ear, and then the inner ear. The coronal view is a nice place to start.
The key feature of the external ear is the external auditory canal, which should be patent but have a thin lining of mucosa. The external auditory canal ends at the scutum a thin sliver of bone along the top of the EAC.
The middle ear begins at the tympanic membrane, which should be so thin you can barely see it. The tympanic membrane articulates with the long arm of the malleus. A key space above the scutum is called Prussak’s space, which is a common location for cholesteatomas. The middle ear should only contain soft tissue and air. The middle ear is divided into upper (epitympanum), middle (mesotympanum), and lower (hypotempanum) segments. You should also be able to see the footplate of the stapes articulating with the oval window.
The mastoids connect with the middle ear and should be filled with air (no fluid or soft tissue). The roof of the mastoids is the tegmen mastoideum.
The inner ear contains the cochlea and semicircular canals. The cochlea should have 2 ½ turns and be surrounded by bright cortical bone. You have 3 semicircular canals (superior, lateral, and inferior) and should be about the same width. The internal auditory canal is hard to evaluate by CT but should be roughly a similar diameter with no expansion or loss of bone.
The facial nerve canal can be confusing. It is easiest to find at the stylomastoid foramen. You can follow it superiorly before turning and going under the lateral semicircular canal. The bone should be intact until it reaches the geniculate ganglion.
You can then turn to the axial views and review the ossicles. The malleus and incus should look like an ice cream cone. Another key feature is the fissula ante fenestrum, or the cortical bone next to the cochlea. This is a common place where otosclerosis can begin.
Finally, you want to review the axial images for everything out of the temporal bone. This includes the brain, sinuses, orbits, nasal cavity, salivary glands, and visible portions of the pharynx.
Summary. A coronal, outside-in approach to the temporal bone is a nice way to systematically review the temporal bone.
Thanks for tuning in and be sure to come back to check out part 2, temporal bone pathology. Or you can see all of the temporal bone videos or all the search pattern videos.
This is a collection of videos about the temporal bone. The temporal bone can be intimidating, especially to those just beginning their review of temporal bone imaging, particularly computed tomography (CT). These videos show you a systematic approach to the temporal bone which can help you master the basics and give you a foundation as you move on to learning more specifics about the pathology.
his case is the fourth and final case that goes with the vascular capstone course. On that page, there is a scrollable case that you can go through to teach you how to approach a CTA of the head in a real patient.
This case is a 41 year-old man after a trauma in a motor vehicle collision (MVC). Take a look and see what you think before continuing on (https://bit.ly/CTAcaseD).
Starting with the CTA of the neck, this is not a normal case. If you follow your normal search pattern, you will see that there are a number of abnormalities, starting from the right internal carotid artery (ICA), which is lumpy and irregular looking. The left ICA is worse, with areas of narrowing, outpouchings, and linear filling defects that represent little areas of the intima that are lifted up by trauma. The little outpouchings along the margins of the vessel are little pseudoaneurysms, or areas where the vessel is injured and contrast is able to leak out into the surrounding area of damaged vessel. Both vertebral arteries are also abnormal with multifocal irregularity and a small pseudoaneurysm on the right.
This is a dramatic example of traumatic vascular injury in the neck. After high energy or penetrating (think gunshot or stab wound), the great vessels can be injured and jeopardize the blood supply to the brain. These injuries are graded on the Denver, or Biffl, scale which ranges from 1-5. You can read more about it on Radiopaedia. Injuries to the vessels in the neck are most commonly pseudoaneurysms, meaning that one layer or more of the vessel is injured and the wall of the aneurysm does not contain all the layers (intima-media-adventitia). Contrast this to intracranial aneurysms, which are true aneurysms and the wall contains all the layers.
This is the last of the case examples for the vascular capstone course. If you haven’t already, I recommend going back to the vascular capstone course, where you can review the other browseable cases with explanations.
