Cranial & Facial Imaging (12)

Question 1

Routine CT Head: Indications (10)

Answer 1

Stroke-initial eval
Headache
Vertigo
Seizures
Unresponsive
Confusion
Neurological Concerns
Mental Status Change
Trauma/Fractures/hemorrhagic strokes (bleeds) best visualized w/o contrast
General Survey

Question 2

Routine CT Head: Scan Type

Answer 2

Axial most common; helical and volume scans increasing in use

Question 3

Routine CT Head: Slice Parameters

Answer 3

2.5mm slice thickness through posterior fossa
5mm through vertex w/matching slice interval
Brain & cranium should always be eval’d w 5mm or less thickness

Question 4

Routine CT Head: Gantry Tilt

Answer 4

Parallel to supra-orbital-meatal line to avoid lens of eye

Question 5

Routine CT Head: w/Contrast (performed as: )

Answer 5

Done when MRI contraindicated (done as Routine CT Head WWO)

Question 6

Routine CT Head: when MRI is preferred

Answer 6

For imaging mass (soft tissue pathologies)

Question 7

Routine CT Head: Algorithm

Answer 7

Standard: 80/30
Bone: 2500/600

Question 8

Routine CT Head: HU for blood (range)

Answer 8

30-45 HU

Question 9

Routine CT Head: HU for brain

Answer 9

20 HU

Question 10

Routine CT Head: Utility of Brain window (80/30)

Answer 10

Supressed image noise
Creates smoother image

Question 11

Routine CT Head: Smoothing Algorithm is used in Volume (3D) Rendering bcuz

Answer 11

Bone 2500/600 creates too much image noise in 3D

Question 12

CT Orbits: Indications (3+)

Answer 12

Proptosis (eye bulging)
Pain
Vision changes
Other abnormalities

Question 13

CT Orbits: Scan Type

Answer 13

Helical

Question 14

CT Orbits: Slice Parameters

Answer 14

1.25mm with matching interval

Question 15

CT Orbits: Gantry Tilt

Answer 15

Parallel to hard palate

Question 16

CT Orbits: Contrast
Timing
(_______ for trauma)

Answer 16

IV contrast: 60 s post-injection
(Non-Con for trauma)

Question 17

CT Orbits: Algorithm

Answer 17

Standard: 400/40
Bone: 2500/600

Question 18

CT Orbits: Reformations

Answer 18

Coronal/Sagittal in both Std/Bone

Question 19

CT Orbits-Imaging for trauma: Most likely course of action

Answer 19

Convert to CT Facial Bones
(orbits-only rare d/t likelihood of other areas being injured if orbits are injured)

Question 20

CT Orbits w/Contrast Indication (1+)

Answer 20

Infection
Other soft tissue concerns

Question 21

CT Orbits: Utility of standard WL

Answer 21

(40)
Matches approx HU of tissue in/around eyes

Question 22

Bone Window: Max visibility of bone

Answer 22

2500 HU

Question 23

CT Facial Bones: Indications (4+)

Answer 23

Facial trauma (most common)
Facial abscess (esp dental)
Mass
Swelling
Other Abnormalities

Question 24

CT Facial Bones: Scan Type

Answer 24

Helical

Question 25

CT Facial Bones: Slice Parameters

Answer 25

1.25 mm with matching interval

Question 26

CT Facial Bones: Gantry Tilt (1)

Answer 26

Parallel to hard palate

Question 27

CT Facial Bones: Contrast Timing (_______for trauma)

Answer 27

IV contrast: 45s post inj (NonCon for trauma)

Question 28

CT Facial Bones: Algorithm

Answer 28

Standard: 400/40 Bone: 2500/600

Question 29

CT Facial Bones: Typical Reformats

Answer 29

Coronal/Sagittal in Standard/Bone

Question 30

CT Facial Bones: FOV lower limit

Answer 30

Includes entire mandible

Question 31

CT Sinuses: FOV

Answer 31

Similar to facial bones but does not include mandible

Question 32

CT Sinuses: Indications (2+)

Answer 32

Sinusitis Sinus Pn Etc

Question 33

CT Sinuses: Scan Type

Answer 33

Helical

Question 34

CT Sinuses: Slice Parameters

Answer 34

3.75mm w/matching interval

Question 35

CT Sinuses: Gantry Tilt

Answer 35

Perpendicular to hard palate (for direct coronal)

Question 36

CT Sinuses: Non Con vs W Con

Answer 36

None If suspected mass: should convert to CT Facial Bones w/Contrast

Question 37

CT Sinus: Direct Coronal Utility

Answer 37

Allows better visualization of air-fluid levels in sinuses

Question 38

CT Sinus: Algorithm

Answer 38

Bone: 2500/600

Question 39

CT Sinus: FOV

Answer 39

All Sinuses Mastoid Air Cells

Question 40

CT Sinus: Most common indication

Answer 40

Acute/Chronic Sinusitis

Question 41

CT Sinus: Acute sinusitis presentation

Answer 41

Clear fluid-levels in sinuses, esp maxillary

Question 42

CT Sinus: Chronic sinusitis presentation

Answer 42

mucosal thickening w/out definite air-fluid level

Question 43

CT Temporal Bones: purpose

Answer 43

Identify tiny changes in mastoid air cells, IAC, inner ear

Question 44

IAC

Answer 44

Internal Auditory Canal

Question 45

CT Temporal Bones: Patient positioning

Answer 45

Direct Coronal

Question 46

CT Temporal Bones: Indications (3+)

Answer 46

Pain Ataxia Hearing Loss Etc

Question 47

Ataxia

Answer 47

Lack of coordination

Question 48

CT Temporal Bones: Scan Type

Answer 48

Helical

Question 49

CT Temporal Bones: Slice Parameters

Answer 49

0.625mm slice 0.315 slice interval (Result: overlapping slices/ultra-high spatial res)

Question 50

CT Temporal Bones: Gantry Tilt

Answer 50

Perpendicular to hard palate if direct-coronal Parallel to hard palate if supine

Question 51

CT Temporal Bones: Contrast

Answer 51

None

Question 52

CT Temporal Bones: Algorithm

Answer 52

Bone: 2500/600

Question 53

CT Temporal Bones: FOV

Answer 53

All sinuses Mastoid Air Cells

Question 54

Routine CT Head: _______ helps prevent blocky appearance in Volume (3D) Rendering

Answer 54

Thin slices w/overlapping Interval

Question 55

approx HU of bone

Answer 55

600 HU

Question 56

Course of action if CT Sinus is ordered for suspected mass

Answer 56

Convert to CT Facial Bones w/Contrast