CT Theory 2 Flashcards

1
Q

Planes of the body

A
  • sagittal: left/right
  • coronal: anterior/posterior
  • transverse (axial): superior/inferior
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2
Q

CT procedure start to finish

A
  1. Patient and/or rex arrives. Asses clinical info and protocol assigned
  2. Patient is prepared fro appropriate protocol: lab work, previous exams/artifacts, communication and consent, prepare IV
  3. Position patient
  4. Acquire scout images
  5. Use scout images to set scan parameters
  6. Perform scan
  7. Dismiss patient
  8. Post-processing and storage of images
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3
Q

What lab tests are performed?

A
  • BUN
  • GFR
  • Creatinine
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4
Q

What medical history is acquired?

A
  • allergies?
  • surgeries?
  • thyroid conditions
  • diabetes
  • hypertension/heart condition
  • pregnancy and breast feeding
  • renal function
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5
Q

Explanation of procedure?

A
  • speak clearly
  • ask questions to ensure patient understands
  • be a good listener, nod, eye contact
  • use language patient understands
  • answer questions, seek clarification
  • be aware of fears and claustrophobia
  • explain as you go
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6
Q

NECT vs. CECT

A

NECT: non enhanced
CECT: contrast enhanced

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7
Q

Phases of contrast injection?

A
  1. Arterial (bolus): early 15-25s, late 35sec
  2. Venous (non-equilibrium):65-80sec
  3. Delayed Venous (equilibrium): excretory = 3-15min
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8
Q

Ways of determining when to trigger a scan post-injection?

A
  1. Smart Prep:Localizer slice taken, set parameters, set ROI, Series of images taken (usually 2secs apart) to track bolus/CT numbers, Scan is triggered when HU threshold is reached
  2. Timing Bolus: measures patient cardiac output
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9
Q

What are retorspective reconstructions?

A

Change DFOV and/or target to produce image series form within raw data acquired

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10
Q

Another name for surface rendering?

A

Shaded surface display

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11
Q

Muscles of the rotator cuff?

A
  • Supraspinatus: lies in the fossa
  • Infraspinatus: large, triangular
  • Teres minor: lies just below infraspinatus
  • Subscapularis: anterior of scapula
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12
Q

When is a CT procedure ordered?

A
  • Bone and soft tissue tumors
  • To add info to radiographs
  • Complex fractures
  • Pre-arthroplasty planning
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13
Q

Advantages of CT over plain radiographs?

A
  • Spatial relationships
  • Ability for comparison of joints
  • Bone and soft tissue can both be demonstrated with one scan
  • Excellent contrast resolution
  • MPR and 3D imaging features
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14
Q

Contraindications for CT procedures?

A
  • Extensive hardware

- Pregnancy

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15
Q

General rules of positioning?

A
  • Lower extremities: supine, feet first
  • Upper extremities: supine, head first
  • Ensure symmetry: no rotation
  • Axial plane of anatomy perp. to scanner
  • Use pillows and sponges to prevent patient motion
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16
Q

Shoulder Exam: positioning, anatomy included, FOVs

A
  • supine, affected arm at side, unaffected arm raised, head first
  • non-contrast
  • include above AC joint to scapular tip
  • Scout: AP and Lateral
  • SFOV: large (body)
  • DFOV: 25cm
  • Slice thickness: 0.5-1mm
  • Slice increment: 0.5-1mm
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17
Q

Shoulder exam: window settings, algorithm, reconstructions

A

-Algorithm: bone
-WW: 2000
-WL: 500
-kVp: 140, mA: 300
-Recons:
Standard soft tissue algorithm
MPR: coronal, sagittal, oblique
Surface rendering if indicated

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18
Q

Elbow: positioning, anatomy included, FOVs, etc.

A
  • prone, affected arm extended over head, or supine with arm by side
  • non-contrast
  • include above elbow joint to below radial tuberosity
  • Scout: AP and Lateral
  • SFOV: large (body)
  • DFOV: 15cm
  • Slice thickness/increment: 0.5-1mm
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19
Q

Elbow: algorithm, window settings, reconstructions

A

-Algorithm: bone
-WW: 2000
-WL: 500
-kVP: 140 mA: 300
-Reconstructions:
Standard soft tissue algorithm
MPR: coronal, sagittal, oblique
Surface rendering in indicated

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20
Q

Wist: positioning, anatomy included, FOVs, etc.

A
  • prone, affected arm extended over head or supine, arm by side
  • non contrast
  • include proximal wrist joint to proximal metacarpals
  • Scout: AP and Lateral
  • SFOV: large (body)
  • DFOV: 10cm
  • Slice thickness/increment: 0.5-1mm
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21
Q

Wrist: algorithm, window settings, kVp, mA, recons

A

-Algorithm: bone
-WW: 2000
-WL: 500
-kVp: 140 mA: 300
-Recons
Standard soft tissue algorithm
MPR: coronal, sagittal, oblique
Surface rendering if indicated

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22
Q

Hip: positioning, anatomy included, FOVs, etc.

A
  • supine, legs flat, DO NOT elevate knees
  • non contrast
  • include above SI joints to about 4cm below less trochanters
  • Scout: AP and Lateral
  • SFOV: Large (body)
  • DFOV: 30cm (symph to skin)
  • Slice thickness/increment: 0.5-1mm
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23
Q

Hip: algorithm, window settings, kVp, mA, recons

A

-Algorithm: bone
-WW: 2000
-WL: 500
-kVp: 140 mA: 400
-Recons:
Standard soft tissue algorithm
MPR: coronal, sagittal
Surface rendering if indicated, pre-op planning, most frequently

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24
Q

Knee/Tibial plateau: positioning, anatomy included, FOVs, Etc.

A
  • supine, legs flat on table, feet taped, or unaffected knee up out of way
  • non contrast
  • include above patella to below fibular head
  • Scout: AP and Lateral
  • SFOV: large (body)
  • DFOV: 20cm
  • slice thickness/increment: 0.5-1mm
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25
Q

Knee: Algorithm, window settings, kVp, mA, recons

A

-Algorithm: bone plus
-WW: 2000
-WL: 500
-kVp: 140 mA: 300
-Recons
Standard soft tissue algorithm
MPR: coronal, sagittal
Surface rendering if indicated, pre-op planning most frequent

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26
Q

Ankle: positioning, anatomy included, FOVs, etc.

A
  • supine, legs flat on table, dorsiflex affected foot, move unaffected out of area of interest
  • non contrast
  • include above ankle joint through calcaneus
  • Scout: AP and Lateral
  • SFOV: large (body)
  • DFOV: 16cm
  • Slice thickness/increment: 0.5-1mm
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27
Q

Ankle: algorithm, window settings, kVp, mA, Recons

A

-Algorithm: bone plus
-WW: 2000
-WL: 500
-kVp: 140 mA: 200
-Recons
Standard soft tissue algorithm
MPR: coronal, sagittal
Surface rendering if indicated

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28
Q

8 cranial bones?

A
  • Frontal
  • Occipital
  • Temporal x2
  • Parietal x2
  • Sphenoid
  • Ethmoid
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29
Q

Bones in the anterior cranial fossa?

A
  • Frontal
  • Ethmoid
  • Lesser wings of sphenoid
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30
Q

Bones in the middle cranial fossa?

A
  • Sphenoid
  • End of carotid canal
  • Temporal bones
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31
Q

Structures in the posterior cranial fossa?

A
  • Jugular foramen
  • Occipital bone
  • Foramen magnum
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32
Q

What cranial bones does the sphenoid articulate with?

A

All of them

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33
Q

What is the tubercullum sellae?

A

The anterior wall of the sella turcica (anterior to the dorsum sellae)

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34
Q

What are the hypoglossal canals? How do they sit in comparison to the foramen magnum?

A

Anterolateral to foramen magnum

-on occipital condyles

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35
Q

14 facial bones?

A
  • nasal bones x2
  • lacrimal bones x2
  • zygoma x2
  • maxilla x2
  • mandible
  • palatine x2
  • vomer
  • nasal conchae
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36
Q

Meninges of brain and their characteristics?

A

Dura Mater: outermost, strongest, continuous with periosteum
Arachnoid Mater: thin, delicate, middle layer, transparent
Pia Mater: inner, highly vascular, adheres to brain’s contours

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37
Q

What space contains CSF?

A

Subarachnoid space: between the pia and arachnoid mater

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38
Q

What does the falx cerebri separate?

A

The cerebral hemispheres

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39
Q

What does the tentorium cerebella separate?

A

Separates the cerebrum and cerebellum

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40
Q

What does the flax cerebelli separate?

A

The cerebellar hemispheres

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41
Q

4 ventricles?

A
  • Right and Left Lateral (frontal/anterior horn, occipital/posterior horns, temporal/inferior horns)
  • Third Ventricle: thin, slit-like, midline just inferior to lateral ventricles
  • Fourth Ventricle: diamond shaped, anterior to the cerebellum and posterior to the pons
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42
Q

What parts of the brain does the lateral (sylvian) fissure separate?

A

The frontal and parietal

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43
Q

Where does the corpus collosum sit? What does it form?

A

Sits above the ventricles, forms the roof of the lateral ventricles

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44
Q

What are gyri? What are sulci?

A

Gyri: folds
Sulci: grooves

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45
Q

What is the difference between grey and white brain matter?

A

Grey: 35-45HU, neuron cell bodies
White: 20-30HU, myelinated sheath on nerves

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46
Q

What is the largest and most dense collection of white matter?

A

Corpus callosum

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47
Q

4 segments of the corpus callosum?

A
  1. Rostrum: most anterior
  2. Genu
  3. Body
  4. Splenium: most posterior
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48
Q

4 cerebral lobes?

A
  1. Frontal: most anterior
  2. Parietal: middle, posterior to central sulcus
  3. Occipital: most posterior
  4. Temporal: anterior to occipital, separates from the parietal lobes by the lateral fissure
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49
Q

Major components of the diencephalon?

A
  • Thalamus: makes up portion of wall of 3rd ventricle, large, oval grey mass
  • Hypothalamus: below thalamus, forms floor of 3rd ventricle
  • Pituitary gland: connected to the thalamus by the infundibulum
  • Epithalamus: most posterior
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50
Q

Where does the pineal gland sit?

A
  • on the roof of the midbrain
  • just posterior to the 3rd ventricle
  • inferior to the splenium of the corpus callosum
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51
Q

Major segments of the brainstem?

A
  1. Midbrain: most superior, at junction of middle and posterior cranial fossa
  2. Pons: middle, large, oval shaped bulge posterior to clivus and anterior to cerebellum
  3. Medulla Oblongata: inferior from pons through foramen magnum
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52
Q

Important structures of the cerebellum?

A
  • Lateral hemispheres: folds of grey matter
  • Vermis: connects the lateral hemispheres
  • Cerebellar tonsils: 2 rounded prominences on the inferior surface
  • Cerebellar peduncles: nerve fiber tracts connecting to the midbrain
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53
Q

What 2 main pairs of arteries supply blood to the brain?

A
  • Internal carotid arteries: anterior circulation

- Vertebral arteries: posterior circulation

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54
Q

Where do the internal carotid arteries enter the brain? What do they branch into?

A

Through the carotid canal of the temporal bone

  • anterior cerebral artery
  • middle cerebral artery (larger)
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55
Q

How do the vertebral arteries enter the brain? What do they unite to form?

A

Through the foramen magnum

-unite to form the basilar artery

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56
Q

Major dural sinuses?

A
  • Superior sagittal sinus
  • Inferior sagittal sinus
  • Straight sinus
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57
Q

In what meninge are the dural sinuses?

A

The dura mater

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58
Q

Where do the dural sinuses drain into?

A

The internal jugular vein

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59
Q

Positioning for a head CT

A
  • head holder or molded sponge
  • patient supine, head first into gantry
  • normal respiration
  • eyes open or closed (can blink)
  • SOML or OML
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60
Q

Why is it preferred to line up the SOML instead of the OML when CT imaging the head?

A

Reduced dose to the eye

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61
Q

Advantages of conventional head CT?

A
  • allow gantry tilt
  • highest image quality
  • reduced radiation dose (minimal overlap)
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62
Q

Disadvantages of Conventional head CT?

A
  • longer exam time
  • limited ability to reconstruct data
  • possibility of missed anatomy, misregistration
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63
Q

Advantaged of Helical head CT?

A
  • shorter exam time (contrast enhanced studies)
  • improved spatial resolution
  • ability to reconstruct, use 3D tools
  • allows slice increment to be changed retrospectively
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64
Q

Disadvantages of helical head CT?

A
  • higher radiation dose

- does not allow gantry tilt

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65
Q

How do we manage beam hardening artifact in the posterior fossa of the head?

A
  • increase kVp

- decrease slice thickness

66
Q

What setting do we acquire CT brain scans in? Why?

A

Standard/soft tissue setting
-WW 160
-WL 40
Because it targets grey and white matter

67
Q

Do we use a wide or narrow window width to acquire CT brain scans?

A

Narrow due to small difference in the tissue attenuation

-allows best contrast resolution

68
Q

CT brain reconstruction algorithm, WW and WL. Is this a wide or narrow WW?

A

Bone
-WW 2500
-WL 400
Wide window width due to large difference in the tissue attenuation

69
Q

Types of intracranial hemorrhage?

A
  • Epidural hematoma: lens-shaped, arterial bleed, mass effect, traumatic injury
  • Subdural hematoma: venous bleed, crescent shaped
  • Subarachnoid hemorrhage: bleeding into ventricular system, increased density with basilar cisterns, fissures, sulci, etc.
  • Intracerebral hemorrhage: traumatic injury, damage to vessels or an aneurysm rupture, well circumscribed, high density region
70
Q

Indication for a NECT Head?

A
  • ICH
  • Early infarction
  • Dementia
  • Hydrocephalus
  • Trauma
71
Q

Indications for both NECT and CECT head?

A
  • mass or lesion
  • arteriovenous malformation
  • metastasis
  • aneurysm
  • headache
  • seizure
72
Q

What is CT angiography?

A
  • CT scan with arterial contrast enhancement
  • evaluate vascular disease
  • gold standard for stroke imaging
73
Q

Advantages of CT angiography over catheter angiography?

A
  • faster
  • widely available
  • non-invasive
  • lower risk of complication
74
Q

Contraindication for a head CT?

A
  • pregnancy (weight risk vs. benefit)

- contraindication for contrast media

75
Q

NECT head: scouts, anatomy included, positioning, FOVs, algorithm, window settings

A
Scouts: AP and lateral
Anatomy included: vertex to skull base
-SOML or OML
-DFOV: 23cm
-SFOV: head
Algorithm: standard
WW: 140 WL 40
76
Q

NECT head: recon algorithm and window settings, technique, post processing

A

Recon algorithm: bone
WW: 4000 WL: 40
kVp: 120-140 mA: 150
Post processing: coronal and sagittal reformats

77
Q

CECT: scouts, anatomy included, positioning, FOVs, algorithm, window settings

A
Scout: AP and Lateral
Anatomy included: vertex to base of skull
-SOML or OML
-DFOV: 23cm
-SFOV: head
Algorithm: standard
WW: 140 WL 40
78
Q

CECT: recon algorithm and window settings, technique, post processing

A

Recon algorithm: bone
WW: 4000 WL: 400
kVp: 120-140 mA: 150
Post processing: coronal and sagittal reformats

79
Q

CECT head contrast volume and scan delay

A

IV contrast: 100ml at 1.0ml/sec
Scan delay: 5 mins
Oral contrast: none

80
Q

Common indications for CT sinuses?

A
  • chronic sinusitis
  • inflammatory sinus disease
  • pro-operative
81
Q

Contraindications for CT sinuses?

A
  • pregnancy

- extensive hardware

82
Q

CT sinuses: scout, anatomy included, positioning, FOVs, algorithm, window settings

A
Scout: Lateral
Anatomy included: entire frontal sinus to sella turcica, and entire frontal sinus to entire maxillary sinus
-OML
-DFOV: 16cm
-SFOV: head
Algorithm: standard
WW: 350 WL: 50
83
Q

CT sinuses: recon algorithm, window settings, technique, post processing

A

Recon algorithm: bone
WW: 4000 WL: 400
kVP: 120 mA: 150
Post processing: coronal and sagittal reformats

84
Q

Are CT sinuses NECT, CECT, or both?

A

NECT

85
Q

Common indications for CT facial bones?

A
  • facial fracture
  • soft tissue injury
  • foreign body
86
Q

Contraindications for CT facial bones?

A
  • pregnancy

- extensive hardware

87
Q

CT facial bones: Scout, anatomy included, positioning, FOVs, algorithm, window settings

A
Scout: AP and Lateral
Anatomy included: entire frontal sinus to mandible and nose to sella turcica
-IOML
-DFOV: 18cm
-SFOV: head
Algorithm: standard
WW: 350 WL: 50
88
Q

CT facial bones: reconstruction algorithm, window settings, technique, post processing

A

Recon algorithm: bone
WW: 4000 WL: 400
kVp: 120 mA: 150
Post processing: coronal and sagittal reformats, helical scans allow 3D surface rendering if indicated

89
Q

Common indications for CT NECT orbits?

A
  • Foreign body

- trauma

90
Q

Common indications for CECT orbits?

A
  • intraorbital mass
  • thyroid opthalmopathy
  • inflammation
  • infection
  • trauma-vascular injury
91
Q

Contraindications for CT orbits?

A

-Pregnancy

92
Q

NECT and CECT orbits: scout, anatomy included, positioning, FOVs, algorithm, window settings

A
Scout: AP and Lateral
Anatomy included: orbital roofs to orbital floors
-IOML
-DFOV: 16cm
-SFOV: head
Algorithm: SOFT
WW: 350 WL: 50
93
Q

NECT and CECT orbits: reconstruction algorithm, technique, post processing

A

Recon algorithm: Bone
WW: 4000 WL: 400
kVp: 120 mA: 200
Post-processing: coronal and sagittal reformats, helical scans allow 3D rendering if indicated

94
Q

CECT orbits contrast protocol?

A
IV contrast: 100 ml at 1.0ml/sec
Scan delay: Split bolus
-50ml @ 1ml/sec
-2 minute delay
-50ml @ 1ml/sec
-scan immediately following second bolus
Oral contrast: none
95
Q

Common indications for CTA circle of willis?

A
  • locate known aneurysm
  • arteriovenous malformation
  • assessment of known intracranial hemorrhage
96
Q

Contraindications for CTA circle of willis?

A
  • pregnancy

- if NECT has not been performed! NEVER do unless a patient has already had a dry scan

97
Q

CTA Circle of Willis: scout, anatomy included, FOVs, algorithm, window settings, technique, post processing

A
Scout: AP and Lateral
Anatomy included: just above frontal sinuses to just below skull base
-DFOV: 25cm
-SFOV: head
Algorithm: standard
WW: 140 WL: 40
kVP: 120 mA: 500
Post processing: coronal, sagittal, oblique, etc.
98
Q

CTA circle of willis contrast protocol?

A
IV contrast: 60ml @ 4ml/sec
Scan delay: smart prep
-ROI on carotid artery
-Scan starts once adequate contrast enhancement of the carotid artery is reached
Oral contrast: none
99
Q

The oropharynx is separated from the larynx by what?

A

Epiglottis

100
Q

Which part of the pharynx has the piriform sinuses?

A

Laryngopharynx

101
Q

Sphenoid sinuses sit where in relation to the nasopharynx?

A

More posterior

102
Q

At what vertebral level is the larynx?

A

C3-C6

103
Q

Where is the thyroid cartilage in relation to the thyroid?

A

Superior

104
Q

Do the salivary glands appear darker or lighter than muscle?

A

Darker

105
Q

Where is the esophagus in relation to the trachea?

A

Posterior

106
Q

Salivary glands

A
  1. Parotid (largest)
  2. Submandibular
  3. Sublingual (anterior to submandibular)
107
Q

Where do the parotid glands sit?

A

Extend from the level of the EAM to the gonion

108
Q

Why do the parotid gland appear different from the other salivary glands?

A

Fatty tissue and lymph nodes within the glands

109
Q

Where do the submandibular glands sit?

A

Extend from the gonion to the hyoid bone

110
Q

The two lobes of the thyroid are joined anteriorly by the?

A

Isthmus

111
Q

Where does the right common carotid artery rise from?

A

The brachiocephalic artery posterior to the SC joint

112
Q

Common carotid arteries bifurcate into the internal and external carotid arteries at what vertebral level?

A

C3-C4

113
Q

Where is the common carotid artery in relation to the internal jugular vein?

A

Medial

114
Q

Where do the internal and external carotid arteries enter the skull?

A

Internal carotid: carotid canal of temporal bone

External carotid: parotid gland to level of TMJ

115
Q

Vertebral arteries ascend through the transverse foramina of C____ to C___?

A

C6 to C1 and enter the skull through the foramen magnum

116
Q

What are typically the largest vessels in the neck?

A

Internal jugular veins

117
Q

Where do the external jugular veins empty into?

A

The subclavian vein

118
Q

Where do vertebral veins drain into?

A

The brachiocephalic vein

119
Q

Patient positioning for CT neck

A
  • head holder
  • supine, head first into gantry
  • suspend respiration
  • suspend swallowing
  • hard palate parallel to gantry
  • reach arms down, depress shoulders
120
Q

Challenges in scanning CT neck?

A
  • Dental work: split the scan superior and inferior to dental work and angle between to avoid streaks
  • Large shoulder: depress shoulders as much as possible
121
Q

How are CT images of the neck viewed?

A
  • MPR
  • Standard/soft tissue WW: 160 WL: 40
  • Soft algorithm: WW: 350 WL: 50
  • Bone: WW: 2500 WL: 400
122
Q

Common indications for CECT soft tissue neck?

A
  • neck mass
  • vascular abnormality
  • lymphadenopathy
  • cysts
  • abscess
123
Q

Common indications for NECT soft tissue neck?

A

-salivary stones: contrast will obscure stone

124
Q

Contraindications for Neck CT?

A
  • pregnancy

- contraindications for contrast media

125
Q

3 categories of strokes?

A
  1. Ischemic
  2. Hemorrhagic
  3. Hypotensive
126
Q

Risk factors to stroke?

A
  • hypertension
  • homocysteine and Vit B deficiency
  • high cholesterol
  • atrial fibrillation
  • heart disease
  • diabetes
  • migraines
  • heredity
  • smoking
  • obesity
  • substance abuse
127
Q

Two main types of ischemic stroke?

A
  • thrombotic: blood clot in artery

- embolic: traveling particle in the bloodstream that lodges in a smaller artery, cutting off blood flow

128
Q

What is a hypotensive stroke?

A
  • rare

- blood pressure is too low, can reduce oxygen supply to the brain

129
Q

What is a TIA?

A

Reversible episode of neurologic dysfunction that could last a few mins to a few hours

  • caused by tiny emboli that lodge in an artery, but then move on or dissolve
  • an indicator of stroke risk
130
Q

TIA of the carotid arteries symptoms?

A
  • vision loss
  • speech
  • partial or temp. paralysis
  • tingling
  • numbness
  • unilateral symptoms
131
Q

TIA of the basilar artery symptoms?

A
  • dim, grey, blurry vision
  • vision loss in both eyes
  • tingling in mouth, cheeks, gums
  • headache, posterior often
  • dizziness
  • nausea, vomiting
  • difficulty swallowing
  • inability to speak clearly (confusion)
  • weakness in arms or legs
132
Q

CTA for stroke imaging is used for?

A
  • show spatial relationship of lesions to the brain tissues
  • evaluate integrity of vessels
  • accurate measurements of stenosis of a vessel
  • evaluate the circle of willis and carotid arteries
  • detect vascular lesions such as dissection or occlusions
133
Q

t-PA is effective when administered within ______ hours after the first signs of a stroke?

A

3

134
Q

CECT soft tissue neck: scouts, anatomy included, FOVs, algorithm, window settings

A
Scouts: AP and Lateral
Anatomy included: mid-orbit to mid-clavicle (t2-t3)
-DFOV: 18cm
-SFOV: large body
Algorithm: standard (or soft)
WW: 350 WL: 50
135
Q

CECT soft tissue neck: reconstruction algorithm, technique, post processing

A

Recon algorithm: bone
WW: 4000 WL: 400
kVP: 120 mA: 150* automatic mA
Post processing: coronal and sagittal reformats, retrospective recons of c spine can be done due to large SFOV

136
Q

CECT soft tissue neck contrast protocol?

A

125ml at 1.5ml/sec

  • split bolus:
  • 50ml
  • 2 min
  • 75 ml
  • scan 20-30secs after 2nd injection
  • oral contrast: sometimes, rare
137
Q

CTA COW and Carotids “stroke protocol”: Scouts, anatomy included. FOVs, algorithm, window settings

A
Scout: AP and Lateral
Anatomy included: aortic arch to just above frontal sinus
-DFOV: 25cm
-SFOV large body
-Algorithm: standard
WW: 250 WL 30
138
Q

CTA COW and Carotids: reconstruction algorithm, technique, post porcessing

A

Recon algorithm: MIP
WW 800 WL 200, thin slices
kVp: 120 mA: 500
Post processing: coronal, sagittal, oblique

139
Q

CTA COW and carotids contrast protocol

A

80ml at 4ml/sec
Scan delay: bolus tracking/smart prep
-ROI on carotid artery at C4
-oral contrast: none

140
Q

Patient position for CT chest

A
  • supine
  • arm elevated
  • feet first into gantry
  • reduce patient motion
  • suspend respiration
  • no rotation
141
Q

Challenges in scanning a CT chest

A

Involuntary motion: respiration and cardiac function
-use shortest scan time possible, scan caudal to cranial (less motion at apices)
Patient Mobility: unable to raise arms above head and hold still
-use immobilization or scan with patients arms at side

142
Q

How are ct chests viewed?

A
  • multiple MPR
  • standard soft tissue: WW 350 WL 50
  • lung: WW 1500 WL -700
143
Q

3 major protocol categories of CT chest?

A
  • Routine CECT chest
  • Hi-res NECT chest
  • CTA chest for pulmonary embolism
144
Q

Common indications for routine CECT chest?

A
  • infection
  • mass
  • empyema
  • correlate with radiographs
  • known or suspected congenital abnormalities
  • trauma
  • lung CA
145
Q

2 protocols for NECT chests?

A
  • Lung nodule protocol: inspiration, thin reconstructions, use when correlating nodule seen on radiography
  • High resolution protocol: inspiration and expiration, asbestos exposure, inhalation injury, interstitial lung disease, diffuse pulmonary disease, bronchiectasis, airway disease
146
Q

Volumetric HRCT

A
  • helical
  • covers entire lung rather than representative slices
  • complete assessment of lung
  • capable of 3D post-processing (MIP and MinIP)
  • primary disadvantage: patient dose
  • include more than one series of scans: supine inspiration and expiration, prone inspiration
147
Q

HRCT supine inspiration vs. expiration vs. prone expiration

A

Inspiration: demonstrated best contrast between air and lung
Expiration: demonstrated air trapping in lung
Prone Inspiration: differentiates disease from the effect of gravity on blood flow and gas volume

148
Q

How to decrease dose n HRCT?

A
  • helical mode for supine inspiration, step and shoot for others
  • can decrease tube mA
149
Q

Contraindications for CT chest?

A
  • pregnancy

- contraindication to contrast media if required

150
Q

CECT chest: scout, anatomy included, FOVs, algorithm

A
Scout: AP and Lateral
Anatomy included: above lung apices to below costophrenic angles 
DFOV: set to patient
SFOV: large body
-Standard soft tissue: WW 350 WL 50
151
Q

CECT chest: Reconstruction algorithm, techniques, post-processing

A

Recon algorithm: Lung WW 1500 WL -700
kVP 120 mA 100-150 (use auto mA)
Post processing: usually create thin slices in MPR
-pitch is greater than 1 for a lot of chest scans

152
Q

CECT chest contrast protocol?

A

80ml at 3ml/sec
Scan delay: 35 secs
-bolus followed by saline flush for all CECT imaging but especially important for chest imaging
-Oral contrast: not used

153
Q

NECT chest: lung nodule: scouts, anatomy included, FOVs, algorithm

A
Scouts: AP and Lateral
Anatomy included: above lung apices to below costophrenic angles
DFOV: set to patient
SFOV large body 
-Standard soft tissue: WW 350 WL 50
154
Q

NECT chest: lung nodule: Reconstruction algorithm, techniques, post-processing

A

Recon algorithm: lung WW 1500 WL -700
kVP 120 mA 80-160
Post processing: thin sections through various nodules, often use edge enhancing algorithm to sharped the resolution of nodule itself

155
Q

NECT chest: high resolution: Scouts, anatomy included, FOVs, algorithm

A

Scouts: AP and Lateral
Anatomy included: above ling apices to below costophrenic angles
DFOV: set to patient/lung field only
SFOV: lung WW 1500 WL -700

156
Q

NECT chest: high resolution: reconstruction algorithm, technique, post processing

A

Recon algorithm: none
kVP 140 mA 150-375
Post processing: thin slices created in lung windows to show detail of lung parenchyma
for prone expiration only include from carina to just below costophrenic angles

157
Q

CTA chest PE: Scouts, anatomy included, FOVs, algorithm

A

Scouts: AP and Lateral
Anatomy included: below hemidiaphragm to apices (inferior to superior) venous runoff: 2cm below tibial plateau to iliac crests
DFOV: 38cm, 48 (venous runoff)
SFOV: large body
-standard WW 700 WL 180 (optimal for vascular)

158
Q

CTA chest PE: reconstruction algorithm, technique, post processing

A

Recon algorithm: site protocol dependent
kVP 120 mA 500
Venous runoff: kVp 120 mA 190
Post processing: MIP with thin slices, coronal image series always created of chest

159
Q

CTA chest PE contrast protocol (method 1 with venous runoff)

A

120ml split bolus
-70ml at 4ml/sec Smart prep ROI over pulmonary artery
-50ml at 3ml/sec 25 secs after first injection
Scan delay: bolus tracking, arterial phase, lower extremity 180 secs after first bolus

160
Q

CTA chest PE contrast protocol (method 2 timing bolus) more accurate

A
  • 20ml at 4ml/sec to measure cardiac output, ROI on pulmonary artery
  • 60-80ml at 3ml/sec, use scan delay calculated
  • average patient = 10-12 seconds post injection