Author: Katie Bailey, MD

Nasopharyngeal cancer staging – 5 minute review

Posted on by Katie Bailey, MD

Nasopharyngeal cancer staging – 5 minute review

In this video, Dr. Katie Bailey takes us quickly through the nasopharynx, a common location of malignancies in the head and neck, and walks us through some quick samples of how they are staged.

Review of the anatomy of the nasopharynx. The nasopharynx is behind the palate and includes the clivus.  The nasopharynx is largely lined by squamous mucosa with lymphoid tissues and muscles. An important landmark is the torus tubarius and fossa of Rosenmuller.   

Nasopharyngeal cancer staging, like other subsites, is based on a T, N, M stage. Nasopharyngeal cancers are predominantly staged based on whether adjacent structures, such as surrounding soft tissues or the skull base, are involved. Unlike the other tumor sites, size is not involved in the T staging.

Example case 1. There is a soft tissue mass filling the nasopharynx, asymmetrically larger on the right. Erosion of the adjacent bony structures, including the clivus, are important. The tumor is extending into the sphenoid sinus. Involvement of the bony structures and sinuses makes this is a T3 tumor, and there were no nodes or distant metastases (not shown).

There is a more subtle example of bone erosion of the posterior wall of the sphenoid sinus and left carotid canal along with the clivus.

Example case 2. There is a soft tissue mass eroding the petrous apex and left aspect of the clivus. MRI better shows the extent of the involvement, where you can see that there is intracranial involvement into Meckel’s cave (trigeminal foramen). The intracranial involvement makes this a T4 tumor. There were no nodes or distant metastases (not shown).

Example case 3. In this case, there are necrotic lymph nodes in the parapharyngeal and prevertebral space as well as extending down the neck at multiple internal jugular levels. The original CT did not show a mass in the nasopharynx, but because of the nodes, a nasopharyngeal cancer is suspected. The PET/CT is able to locate the abnormality along the left torus tubarius. The local nature of this tumor makes it T1, but the bilateral lymph nodes make it an N3 for nodes.

Extra case. An incidental polypoid mass is seen in the left nasopharynx on a brain MRI with minimal peripheral enhancement and central reduced diffusion. The homogeneously low T2 appearance and reduced diffusion make this suspicious for lymphoma, although you would not be able to tell until this lesion had been biopsied.

Thanks for checking out this quick video on nasopharyngeal cancer staging. Be sure to tune back in for additional videos on staging of the other head and neck subsites.Also take a look at the head and neck topic page as well as all the head and neck videos on the site.

 

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Oropharyngeal cancer staging – 5 minute review

Posted on by Katie Bailey, MD

Oropharyngeal cancer staging – 5 minute review

revised 11/12/2022
N.B. The initial version of this video had a few small errors in the staging, so we have corrected them.

In this video, Dr. Katie Bailey describes the anatomic subsites of the oropharynx and reviews how tumors are staged through four quick example cases.

Review of oropharynx anatomy. The oropharynx includes the tonsils (both lingual and palatine), the squamous mucosa of the pharynx, the uvula, and the vallecula.   oral cavity includes the lips, teeth, hard and soft palate, gingiva, retromolar trigone, the buccal mucosa, and anterior 2/3 of the tongue. The masticator space contains the muscles of mastication, the mandible, branches of the trigeminal nerve, lymph nodes, and minor salivary glands. 

Oropharyngeal cancer staging. Tumor (T) staging is based on the size of the tumor or invasion through adjacent structures. Nodal (N) staging is based on the number, location, and size of nodes, and metastasis (M) staging is based on the presence or absence of distant sites of disease.

Example case 1. There is a 2.4 cm mass of the right palatine tonsil. There is level 2 and 3 adenopathy. The lymphadenopathy compresses the jugular vein and displaces the adjacent sternocleidomastoid.  The size of the tumor makes this a T2 lesion, and the unilateral adenopathy less than 6 cm with multiple nodes makes it N2b. Because metastases can’t be evaluated with this information, it is given an ‘X’ for M staging right now.

Example case 2. There is a 3.2 cm mass in the tongue base and extending into the vallecula. There is no extension into the adjacent structures or fat. There is a single left sided level 2 lymph node that is somewhat prominent but isn’t definitely abnormal. That makes this a T2N0Mx tumor. If a PET or biopsy later shows that the node is positive, the staging can be changed.

Example case 3. There is a subtle mass of the right lateral wall of the oropharynx involving the tonsillar pillar and tongue base. This one is quite hard to see. There are cystic necrotic lymph nodes on the right, but none greater than 6 cm. A PET/CT showed no distant metastatic disease. That makes this a T1N2bM0 tumor.

Example case 4. This patient presented with cervical lymphadenopathy on the left but had no clear primary tumor in the oropharynx. There was no mass of the tongue base or elsewhere. The patient had a lung node suspicious for metastatic disease. A PET/CT showed that there was a primary in the soft palate. The mass was detected only by PET/CT. The final staging for this cancer is T1N2bM1.

Thanks for checking out this quick video on oropharyngeal cancer staging.

Thanks for checking out this quick video on oral cavity cancer staging. Be sure to tune back in for additional videos on staging of the other head and neck subsites. Also take a look at the head and neck topic page as well as all the head and neck videos on the site.

 

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Oral cavity cancer staging – 5 minute review

Posted on by Katie Bailey, MD

Oral cavity cancer staging – 5 minute review

In this video, Dr. Katie Bailey takes on a common topic and describes how cancers of the oral cavity are staged through three quick example cases.

Review of oral cavity anatomy. The oral cavity includes the lips, teeth, hard and soft palate, gingiva, retromolar trigone, the buccal mucosa, and anterior 2/3 of the tongue.

Retromolar trigone. The retromolar trigone is a common crossroads where a lot of pathology occurs and it can cause referred ear pain. Mandibular invasion can also occur with masses that occur in this location.

Oral cavity cancer staging. Tumor (T) staging is based on the size of the tumor and depth of invasion. Nodal (N) staging is based on the number, location, and size of nodes, and metastasis (M) staging is based on the presence or absence of distant sites of disease.

Example case 1. This example case involves the oral tongue and measures 2-4 cm. It has ipsilateral lymph nodes less than 3 cm. This makes this a T2N2 tumor. Because metastases can’t be evaluated with this information, it is given an ‘X’ for M staging right now.

Example case 2. This shows a subtle left tongue cancer measuring less than 2 cm. There are no lymph nodes. That makes this a T1N0Mx tumor.

Example case 3. This case is a hard palate tumor with bone erosion. The involvement through adjacent structures (the bone of the hard palate) makes this a T4 tumor. There is no nodal involvement, making this a T4N0Mx cancer.

Thanks for checking out this quick video on oral cavity cancer staging. Be sure to check out the head and neck topic page as well as all the head and neck videos on the site.

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Basics of Spine Interpretation in 5 minutes

Posted on by Katie Bailey, MD

Basics of Spine Interpretation in 5 minutes

In this lecture, Dr. Katie Bailey walks us through a rapid lecture about how to approach the basics of the spine. In about 5 minutes, you can learn most of what you need to know about spine interpretation when you first sit down to look at spine imaging.

This approach is based on the ABCDEs of spine. Each letter tells you something about what you should be looking for on the imaging.

Alignment. The way the vertebral bodies are oriented with respect to one another is alignment. This means lateral curvature (scoliosis), AP curvature (lordosis or kyphosis), and translation. Listhesis is conventionally described based on the level above with respect to the level below.

Bones. When thinking about the bones, you should look at the characteristics of the bones themselves. On CT, that could mean loss of normal bone density (lytic) or increased bone density (sclerotic). On MRI, you describe the appearance of a lesion with respect to the adjacent marrow. It is either hyperintense (more intense) or hypointense (less intense) compared to the normal marrow.

Cord/cauda equina. The cord itself is a key part of the image and you should look for any lesions within the cord or cauda equina. The cauda equina should be around the L1 level.

Disc. The discs have a wide range of degenerative pathology, which is discussed elsewhere. You should describe degenerative disease as well as any other abnormal conditions of the disc, such as infection.

Everything else. Finally, you should look at soft tissues and surrounding structures outside the spine. This is slightly different at each level of the spine where the structures vary slightly.

Summary. With this quick approach, you can rapidly move from a spine novice to a spine apprentice and you’re ready to learn more about different pathology within the spine. Check out some of the other spine videos to learn more about topics such as spine tumors, demyelinating disease, and degenerative disease.

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Skull Base Foramina Imaging Anatomy

Posted on by Katie Bailey, MD

Skull Base Foramina Imaging Anatomy

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.

Check out more of our content on head and neck imaging by seeing all H&N related posts or on the H&N Imaging Topic page.

 

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Spaces of the Head and Neck

Posted on by Katie Bailey, MD

Spaces of the Head and Neck

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.

Check out more of our content on head and neck imaging by seeing all H&N related posts or on the H&N Imaging Topic page.

 

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Head and neck anatomy landmarks

Posted on by Katie Bailey, MD

Head and neck anatomy landmarks

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.

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Cervical Lymph Node Stations – a landmark approach

Posted on by Katie Bailey, MD

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:

1. Anterior belly digastric
2. Submandibular gland
3. Hyoid bone
4. Cricoid cartilage
5. Sternocleidomastoid muscle
6. Clavicles
7. Carotids
8. Sternum

Hopefully this helps you be more clear in your reports and better understand the different lymph node levels in the neck.

Thanks for tuning in and be sure to check out the head and neck topic page as well as all the head and neck videos on the site.

 

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Temporal bone CT pathology

Posted on by Katie Bailey, MD

Temporal bone CT – Pathology based approach

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.

Thanks for tuning in and be sure to come back to check out part 1, temporal bone CT search pattern. Or you can see all of the temporal bone videos or all the search pattern videos.

 

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Temporal bone CT search pattern

Posted on by Katie Bailey, MD

Temporal bone CT search pattern

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.

 

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