9. MRI Flashcards
MRI- Simplified • The patient is placed in a \_\_\_\_ • A radio wave is sent in • The \_\_\_\_ wave is turned off • The patient emits a signal which is received and used for : • \_\_\_\_ of the picture
magnet
radio
reconstruction
MR units: magnets
- ____ 0.1-0.3 T
- Resistive 0.02-0.4T
- ____ 0.3-4.0T(cooled with liquid nitrogen and helium)
- 1T = 10000G( Gauss)
- Earth’s magnetic field : 3-6 G
- Commonly used MR magnets: 0.5-1.5 T
Measured in ____
permanent
superconductive
teslas
Neck - mid sagittal
Typical sagittal shots
• Photoshopped and pressed invert button to give us catscan of same image (LOOK AT TRANSCRIPTION)
○ Mandible opacified area is cortex in Catscan
○ Mandible is now inverted so bone is ____ on MRI!
When get to joint and TMJ, we typically use more catscan but now we are shifting more to MRI
Critical area to reinforce what bone is
• In spine: marrow is ____ where cortex is now ____
Now looking upwards: nose to toes where we see cerebellum, turbinate’s and sinus
Can see condyles through angulation - now we can see all musculature (pterygoids, masseter, etc.)
black
highlighted
black
Ethomid sinusitis, maxillary sinusitis
Concha with uniform bright ____ in maxillary sinus (may have soft tissue)
Bone here is ____
lesion
dark
Ameloblastoma: T1 weighted images of images
Ameoloblastoma: benign, very aggressive, single or multilocular, can be cystic
This looks like ____ ameloblastoma with line around it
• Some facial swelling
Can see teeth that look like extraction sockets - ____ structures with dentin and enamel
cystic
opacified
Coronal T2W image w/ contrast
____ put in to isolate tumor/lesion
• Can see bands of ____ are amazingly highlighted so you can see even convolutions in brain (not focus though)
contrast
soft tissue
OKC - ramus Fat suppressed MR T1W before and after contrast
Even on MRIs, can tweak algorithm:
• CATSCAN can do maximum ____ and reconstructive
algorithms
• Can do same thing with ____
○
Can remove ____ tissue (fat suppressed)
Fibrous osseous tissue with patient who is very swollen compared to normal side (where big star is)
HARDLY ANY DIFFERENCE BT ____ AND ____
intensity
MRIs
dentin/enamel
air
OKC: coronal T1W fat suppressed and T2W MR
Fat suppressed: orchestrated in formulas so you can see either ____ tissue window, ____ window, ____ suppressed (remove fat so you are not seeing it as clearly)
• Gives our eyes a different way (adipose tumor that will suppress fat and lose tumor)
«_space;in area of parotid, benign but significant excision needed to remove that (do not have to know disease name although he did identify it)
T1: amount of timing of ____ that they use for each version
• Tweak machine to angulate and orchestrate ____
molecules on a T1 and T2
T1 and T2 often pick up different features
soft bone fat magnetism water
Odontigenic Myxoma D/D w/ CEOT Ameloblastoma
CEOT: calcifying ___ ossifying tumor
• Very ____ - either water or fat in there
Here you can see masseter out here
Can see pulp in this slice
bright
Squamous Cell Ca of mandibular gingiva-left (*) Arrow shows enhancement of mandibular nerve (involved)
Down in region where arrow is
• Right side = black is ____, greyish area is ____ and black
area is tooth, sinuses
• LEFT SIDE: asterisk - bone cortex is here but marrow is
different on left compared to right (more radiodense - ____ arrow)
○ In buccal space area we have signal coming back that is opaque so more ____ there than should be (soft tissue tumor)
cortex
marrow
white
tissue
Appearance of various tissues in T1 & T2W images
Tissue
T1W:
T2W:
Water
T1W:
T2W:
Fat
T1W:
T2W:
Fibrous tissue
T1W:
T2W:
Organs
T1W:
T2W:
Tumors
T1W:
T2W:
Fresh blood
T1W:
T2W:
Old blood
T1W:
T2W:
Air
T1W:
T2W:
Bone, calcium
T1W:
T2W:
DARK
VERY BRIGHT
DARK
DARK
(everything else is pretty similar/the same)
Normal appearance
NOW TMJ ANATOMY ON MRI’S
• Missing slide: closed and open
○ CLOSED:
• Condyle sitting nicely in glenoid fossa
• Disk is ____ when condyle is in reprose in glenoid fossa normally (closed)
• Little bit of banding at top and then rest of it goes anterior underneath articular eminence
• Lateral pterygoid is superior and inferior
• Bilateral zone is compressed
• Once we are open though
○ OPEN:
• Articular eminence has ____ follow down slope
• Disk is locked anteriorly - may hear ____ (cannot tell what is happening in normally contoured condyle with soft tissue issues on regular panoramic or catscan
• Can tell by ____ or clinically
superior anterior
condyle
click
MRI
T1 w sagittal MR view
• ____ of the condyle
• ____ of the disc relative to
the position of condyle
• Assess the joint space in these images- closed and open
CAN ONLY SEE JOINT ON ____
• Best image to assess condyle, TMJ pathologies!
position
position
MR
Sagittal T1W Mr
- ____ position and shape
- ____ and shape
- Cortical border of ____
- ____ eminence
condylar
disc position
condyle
articular
Anterior disc displacement
____ is not completely smooth, is that causing
issues with opening
Disk looks like its going beyond ____ which could be reason why patient is having pain or experiencing issues opening ja
condyle
articular eminence
T2W/proton density sagittal images showing eroded condylar head. psoriaric arthritis
Now proton modification with machine
• Articular eminence is stretched out but ____ bone we see (want it to be smooth) meaning degenerative changes (disk or condylar head)
• Any ____ from punched or sports, push into joint leading
to ____ can be one cause of this
• Can also just be arthritic changes
irregular
trauma
hemarthrosis
Coronal view: Shepard’s Hook! Osteo Arthritis
____ growths (even though growing outward) still degenerative and not healthy
• Irregular
• Is patient symptomatic?
Does it require surgical intervention to recountour and clean out regeneration
expohytic
Bird beaking: classic OA/Disc displacement
Sagittal view
• Bird beaking - seen on conventional ____ as well
○ Degenerative usually ____
○ Irregular on condylar head - can catch or hook onto
disk
○ Doing opening and closing, lateral and coronal views
to see movement
panoramic
osteoarhritis
This is how ____ tumors are on T1Ws: a case of synovial chondromatosis showing intermediate signals from the R condylar area
Now moving away from TMJ but within ____ capsule you can get tumors in there as well - not very good prognosis lesions to get
bright
synovial
Silastic implants for disc replacement. Sagittal CT soft tissue window
Sometimes we have to replace what is up there with new condyle (____) or get little template like silastic disk (____) to allow remnant of condyle to translate along articular eminence
MRI more challenging to look at
• Bony lesion of anything including TMJ = lean more towards ____ or ____
○ But medical CT has much more ____ so put in perspective
• Thinking more soft tissue and disk displacement type of issues or even myofacial pain in oral medicine = ____ (open, close, coronal, lateral)
○ Will not typically use ____ for MRI
reconstruction
artificial
cone beam medical CT radiation MRI contrast
