CT NECK:

 

Helpful Links:

NECK NODE LEVELS (CLICK)

 

axial node levels

 

CG Notes:

 

95% of tumors are SCCa

 

start with pharynx, muscular tube

 

hypopharynx behind larynx

 

oral cavity - mostly tongue

 

posterior tongue is oropharynx

 

start with mucuosal sapce

 

three layers of deep cervical fascia

 

outside muscles is middle layer of DCF

 

Masticator space:  

muscles lateral to pharynx

extends up to temporal muscles

could have process spread up to temporalis

all spaces connect to skull base- need to know this

 

MS:  msucles:  masseter, pteryoids

mandible- teeth (cause for disease, infx)

CN 5 supplies this:  Foramen ovale, looking for skull base and perineural spread

 

Parotid space:

superioficial layer of DCF

deep comp and superficial 

in re. to retromandibular vein- for surgery

 

contains salivary gland

nodes

CN 7*** facial

 

most common parotid  is BMT ***

lymph nodes- lymhooma, inflammatory

CN7:  can't follow through parotid, is in region of RMVein

 

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CaroSpace:

comoposed of all three layers

 

carotid artery

jug

9-12 CN

nodes around it, not in 

 

PPS (parapharynx)

contains all three layers of DCF

medial to pterygoids

 

center of lateral face

 

CONTAINS FAT

VEnous plexus

 

displacement of this space localizes the mass

bright on T1, Black on CT

 

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posteior spaces:

Periverteral

retropharyngeal

posterior cervical

 

perivert:  around vertebrae

 

wraps all around spine

 

contains vert, disks, paraspinsous, prevert msuceles, nerves 

VERY TOUGH FASCIA:  CARPET OF NECK - SURGEONS, hard for lesions to extend beyond perivert space.  look for MEYLOPATHY CORD DISEASE

 

retropharyngeal space:
only reallyseen when pathological

fat and nodes in this

tumors can drain here

pharynxgitis can cause abscess in retropharyngeal space

 

posteior cervical space: 

aka posteiror triangle

 

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if i divide h and n in to spaces, easier to dignogse disaese

 

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how to Create DDx:

 

is it neoplastic with aggressive features, breaking boundaries

or benign, staying in the space

 

could be transpatial esp if congenital like lymph malf

 

aggressive lesions destroy fascia

 

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common nasopharyngeal mass: 

NP Ca

can eat into muscles of mastication

 

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mastricator spce mass:

showing low attenuation just medial to angle of mandible

 

look at bone windows

 

look at dental infection, usualy in the molars or premolars

 

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another masticator space mass, centered in muscles of MS

could be sarcoma / rhabdomyosarcoma, think about in kids

 

in adults think about mets or lymphoma

 

look for intracranial perineural spread

 

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carotid space masss:

 

could be psuedoanrysm, JVthrombus

or nerve based

nerve sheath tumors:  neurofibroma vs. swhanoma, one enhances more

 

crazy enhancing mass in CarotidSpace

think of PARAGANGLIOMA** multiple locs in cluding carotid body

 

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Parotid space lesion:

look for location relative to retromandibular vein / CN 7

 

BMT vs. malignant neoplasm, can't always tell on imaging

 

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sometimes hard to see dep lobe of partoid space masses

 

can appear to be in the masticator space

 

Deep Lobe BMT: medial to body of mandiblecoming from lateral to medial

 

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prevertebral muscle space mass:

look for dural extension

could be phlegmon from discitis/ osteo

 

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retropharyngeal space lesion:

 

low atneuation:  usu retropharengeal abscess

 

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posterior cervical space mass:

 

cystic hygroma

often lymphoma here

 

 

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mutispacial masse:  malformations congeital

 

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of note

 

enlarged lymph node in level 2 is 15 mm and only measured on axials, per AB

all other levels 10 mm is the cutoff

 

easeier to asses most levels on sag images

CT TEMPORAL BONE:

 

Good website:for anatomy

http://uwmsk.org/temporalbone/

 

 

another temporal bone anatomy from headneckbrainspine:

 

How to look at a temporal Bone CT

By SG

As per AF

 

Start from outside to in

Pull up axial and coronal at same time

That way you can see where you are in the temporal bone on axial

Find plane of the EAC on the coronal and use that image

Go with path of sound wave

Sound enters and hits tympanic membrane

You may not see TM always but it should be thin

Now on coronal you can appreciate the epitypanum, mesotympanum, and hypotympanum of middle ear cavity

Note the scutum on the coronal (this is blunted in cholesteatoma, which there are two types)

Follow the ossicles: malleus, incus, stapes.  Stapes inserts onto oval window (MISO)

The oval window is sorta abutting the basal turn of the cochlea

Posterior to the oval window is the round window which should be air filled

Its air filled to act as a backwards blowout valve

If the sound is loud, the round window allows air to push back into the middle ear cavity I guess, not tot sure

Kinda moving into the semicirc canals (SCC)

Theres superior, lateral, and posterior.  Use coronal for help on these

The posterior is not really pointing posterior, rather its in the plane of the petrous apex. 

When you see this, look just back from this and you’ll see the vesticular aqueduct.

This V.A. can be increased in size as cause for hearing loss in child.

Go anterior to this on the inner table and find the cochlear aqueduct.

This is below the level of the IAC so don’t confuse it

The cochlear promontory.  This is the convex outward curvature of the otic capsule, seen on axials at the level of the round window.  This is helpful for diagnosis of otospongiosis and / or diag of glomus tympanicum

Re. cochlea:  look at modiolus.  This is the calc portion at the base.  This looks very itnresting on electron microscopy and can look up on google

The course of the facial nerve:  need to know:  there is a genu which is nicely seen on coronal as well.  Coronal hosws the exit out the stylomastoid foramen pretty well. 

 

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Can't miss findings on CT Neck:
Can't miss a jugular or sinus vein thrombosis.

 

 

Some addt'l points:

Think about dental related pathology, look up dental hx and look for peridontal disease including periaipical abscess. 

Some common congenital things:
TGDC:  In the midline or slightly off, kids

2nd Branchial Cleft cyst:  between carotid sheath, SCM, and Submandibular gland (in the middle of all three)

Ranula:  Sublingual and submandibular region

 

Acc. to MW:  SCM and mylohyoid most important muscles to know in neck

 

If see tonsillar process in adults, think about underlying lymphoma

 

SINONASAL CT:

 

Good website for anatomy:

http://uwmsk.org/sinusanatomy2/sagittal/sagittal.html