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Mosby CT review > Imaging Procedures CHEST > Flashcards

Imaging Procedures CHEST Flashcards

1
Q

True/ False. All MDCT scanner systems require a breath hold to complete a chest CT

A

False. Some scanners have sufficient speed that it can scan without the breath hold and still give motion free images

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2
Q

What is the key factor of helical scanning that makes scanning the chest in an entire breath hold possible

A

speed

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3
Q

What is the purpose of having the patient hold their breath during a chest CT

A

creates motion free images

eliminates artifacts

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4
Q

MDCT vs. SSCT scanners allow for these 3 technical improvements

A
  1. better differentiation of pulmonary nodules
  2. high quality MPR techniques
  3. simultaneous high resolution imaging
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5
Q

The pitch in a chest CT needs to be set in accordance to the patient’s ability to do what

A

hold their breath for the length of the scan

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6
Q

How should the patient be positioned during a chest CT

A

supine

arms above the head

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7
Q

What part of the body is a common site for metastatic deposit that can be observed in a chest ct ?

A

adrenal glands

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8
Q

What field of view is needed to acquire a chest CT ( structure A–> B)

A

above lung apices to costophrenic angles

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9
Q

What forms the costophrenic angles

A

the points at which the chest wall and diaphragm meet.

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10
Q

Low dose chest CTs are particularly important in these two populations

A

children

pregnant women

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11
Q

Why do images have to be viewed under multiple window settings in the chest

A

different structures in the chest yield different CT densities requiring different windows
(bone, lung, mediastinum)

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12
Q

High spatial frequency algorithms should be used for which of these indications:

  • evaluate nodules in lung
  • bone metastases
  • chest fractures
  • air way disease
A

bone mets
fractures
air way disease

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13
Q

Why are 3D MPR techniques valuable when imaging the chest

A

it helps to see the surrounding vascular around a particular vessel so when its viewed in a cross section its not mistaken for a pulmonary nodule

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14
Q

Whats the window level and width for the following structures

A

Lung tissue
WL: -450 WW: 1400

Mediastinum
WL: 40 WW: 350

Bone:
WL: 300 WW: 2000

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15
Q

yes/ no . Does the chest already have inherent contrast to it to which sometimes IV contrast is un necessary?

A

yes

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16
Q

What can we presume if there is contrast enhancement showing up in a lung mass or nodule

A

tumor is malignant.

It has vascularity

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17
Q

Indications for a chest Ct WITH Contrast :

A
  • mediastinum & vasculature evaluation
  • lung/ hila abnormalities
  • disease in chest lymph nodes
  • CTA
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18
Q

True/ False. Every vessel in the chest gets the same delay time

A

false. time is vessel dependent

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19
Q

What should the injection rate range from when injection contrast in the chest

A

2.5- 4 mL/ sec

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20
Q

True/ false. Superior vena cava typically has a low iodine concentration

A

false. High

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21
Q

2 ways to avoid an artifact in the mediastinum when doing a chest CT with contrast

A
  1. dilute contrast media [C] with saline. Bolus inject it

2. image inferior to superior

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22
Q

what can be used to see the esophagus better on a chest CT

A

oral barium sulfate

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23
Q

What technique is applied to show diffuse lung disease

A

High resolution CT

HRCT

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24
Q

What parameters maximize resolution in HRCT scanning

A
  1. high spatial frequency kernel
  2. axial thins ( 0.6- 2 mm)
  3. reduced DFOV
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25
Q

indications for HRCT chest CT

A 
Bronchitis
emphysema
asthma 
cystic fibrosis
COPD
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26
Q

True/ False . Image spacing in an HRCT slice decreases

A

false.

increases

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27
Q

data acquisition for a HRCT of chest occurs when during the breathing cycle

What does forced expiration show us when scanning ?

A

when they cease breathing after a full inspiration

air trapping in small airway disease

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28
Q

how can prone positioning of the patient help with diagnosis vs having them regularly laying on their back

A

differentiates between the edema based changes seen in the chest at the base of the lungs

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29
Q

What retrospective reconstructive techniques can be a good substitute for HRCT images

A

reconstructing an image with a target DFOV, high resolution kernal , and 0.6mm width DFOV

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30
Q

What is the min-IP technique?

A

[Minimum intensity projection technique]

where the pixels that appear on the screen represent the minimum attenuation value on each ray

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31
Q

What two techniques can demonstrate air trapping in the patients lungs

A

imaging them at forced expiration

minimum intensity projection techniques

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32
Q

Whats the difference between a regular PE and a saddle PE ?

A

regular PE happens when a clot dislodges from an extremity and migrates to the pulmonary vessels preventing blood flow to lung tissue

saddle PE sits between bifurcation of left and right pulmonary artery

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33
Q

What is the Valsalva effect

A

a breathing method that may slow your heart when it’s beating too fast.
(you breathe out strongly through your mouth while holding your nose tightly closed)

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34
Q

What does CTPA stand for?

Why do we acquire this scan caudocranial?

A

CT pulmonary angiogram

  1. reduces motion artifact in chest if they cant hold their breath for the length of the scan
  2. less streaking artifact in superior vena cava
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35
Q

What rate do we inject for a CTPA?

What range in volume is acceptable for contrast administration for a CTPA ?

A

4-5 mL./ sec via 18 or 20 G catheter

80- 150 mL

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36
Q

What type of contrast could be used to increase patient comfort during a CTPA?

Pushing an extra saline flush can help the image how?

A

low-osmolar or iso-molar

  1. rids the remaining saline from tubing/ peripheral veins
  2. improves contrast visualization
  3. decrease nephrotoxicity
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37
Q

How can ECG gating benefit a cardiac CT

A

eliminates pulsing artifacts caused by heart motion

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38
Q

what’s the difference between prospective gating and retrospective gating?

A

Prospective gating: syncs data acquisition with the cardiac cycle. Data acquired only at diastole

Retrospective Gating: data acquisition occurs through entire cardiac cycle

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39
Q

How long after contrast administration should a delay image be obtained in a CT Pulmonary Angiogram

What field of view is imaged in that delay?

A

2- 3 min

same field of view + iliac crest to ankles

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40
Q

What does CTV stand for?

How do CTVs aid in differential diagnosis?

A

CT Venography

identifies deep vein blood clots

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41
Q

What does the “CAC” in CAC quantitation stand for ?

What does CCTA stand for ?

A

Coronary artery calcium

Coronary CTA

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42
Q

What does CAC quantitation tell us ?

In what was is this study limited? what can it not evaluate?

A
  • presence of CAC indicates atherosclerotic disease
  • In scanning, it measures the amount of calcified plaque in the vessels
  • limited because it cant distinguish those plaques in the body that are not calcified
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43
Q

At what stage of a cardiac CTA is CAC quantitation employed

A

as a pre contrast component of a cardiac CTA

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44
Q

Describe the prospective gating approach using MDCT scanning in CAC quantitation

A
  1. scan in diastole while monitoring ECG rhythm

2. percentage of the R-R interval will trigger data acquisition during the T wave

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45
Q

What is the Agatston Scoring system?

True/ False. The scoring system remains the same regardless of gender or age

A
  • system that measures the volume and density of calcium within coronary arteries
    false. Changes based on age and gender
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46
Q

Based on the Agatston scoring system, areas of calcium deposits are those that are greater than what mm-squared? Greater than what HU?

A

> 1 mm-squared

> 130 HU

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47
Q

List the ranges that correspond with the following coronary artery calcium grades

  • minimum
  • mild
  • moderate
  • extensive
A

minimum 1-10
mild 11- 100
moderate 101-400
extensive >400

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48
Q

Fill in the blank.

Sequential _____ images, sharing the same border, are acquired from ________ to _____________.

A
  1. axial
  2. aortic arch
  3. base of heart
49
Q

True/ False. Patients with elevated heart rates are typically put on beta blockers before getting a CAC study

A

False.

50
Q

To avoid valsalva effect during a CTPA scan when should the data acquisition occur?

A

During shallow breathing

51
Q

2 reasons why a CTPA scan be acquired in a caudocranial direction

A

incase patient cant hold their breath for the entire length of the scan

less streaking artifact from SVC

52
Q

Around how much contrast is administered in a CTPA?

What flow rate is used ?

What catheter gauge?

Name two categories of contrast agents used in CTPAs

A
  • 80 to 150 mL
  • 4-5 mL/sec
  • 18 or 20 gauge
  • low-osmolar or iso-molar
53
Q

Why does injecting saline after contrast administration prove beneficial

A

gets all contrast out of IV tubing and peripheral; vessels

increases contrast enhancement

decreases nephrotoxicity

reduces artifact created from dense contrast

54
Q

How does incorporating ECG gating aid in a cardiac scan?

A

eliminates pulsating artifact caused by heart motion

55
Q

what’s the difference between prospective gating and retrospective gating?

A

Prospective gating: syncs data acquisition with the cardiac cycle. Data acquired only at diastole

Retrospective Gating: data acquisition occurs through entire cardiac cycle

56
Q

What does CAC and CCTA stand for ?

What is the indication for a CAC scan

A

Coronary Artery Calcium

Coronary CTA

57
Q

CAC quantitation measures what?

In what way is this study limited ?

A

calcified atherosclerotic plaque

Does not account for non calcified plaques

58
Q

Describe the prospective gating approach for data acquisition

How does it benefit the patient

A
  1. Scanning the heart happens in diastole ( when heart is relaxed) while ECG rhythms are being obtained
  2. Data acquisition is triggered by a user defined R-R interval
  • reduces patient dose and scan variability
59
Q

what component of a cardiac CTA is CAC quantitation employed

A

pre contrast component

60
Q

What does the Agatson scoring system tell us?

A

the density of calcium deposits in coronary arteries.

61
Q

True/ False.

The Agatson score remains constant regardless of a patients age or gender

A

false. changes based on age and gender

62
Q

List the appropriate ranges for each of the grades for CAC scoring

  • minimal
  • mild
  • moderate
  • extensive
A
  • minimal (1-10)
  • mild (11-100)
  • moderate (101- 400)
  • extensive (>400)
63
Q

True/ false. CAC quantitation on MDCT scanners are performed as a high dose cine- sagittal acquisition

For this study sequential sections are contiguously acquired from what structure to what?

A

-False

low dose , cine- axial -acquisition

  • aortic arch—>base of heart
64
Q

Why are CAC studies typically subject to motion artifact ?

How so some CT systems eliminate this artifact ?

A

patents who have elevated heart rates are usually imaged without the administration of a beta

take multiple axial images within set time intervals

65
Q

T/F. Calcium, mass and agatson score are already tracked within CT software

A

T

66
Q

What benefit does dual energy MDCT technology offer when scanning

how does it help in CAC scanning

A

allows you to switch voltages within the same scan ( from 80 to 140 kvp)

differentiates between contrast build up and calcified plaques

reduces radiation dose because you dont need multiple scans

67
Q

Which scan looks at the arterial blood flow through the heart

A

Coronary CTA

CCTA

68
Q

What comprises the coronary arteries and where does it arise from ?

A

Left and right Coronary artery arise from the aorta

69
Q

How many branches stem off the Right coronary artery (RCA)

A

6

70
Q

How many branches stem off the Left coronary artery (LCA)

A

2

71
Q

Name the branches coming off the RCA

Hint: Trace your nose. Arteries sound like the position of these structures

A
  1. Conus artery
  2. sinus node artery
  3. Posterior descending artery
  4. R. Atrial branches
  5. R. Ventricular branches
  6. Posterior left ventricular branches
72
Q

Name the branches coming off the LCA

A

Left Anterior descending

Left Circumflex

73
Q

The posterior descending artery ( branching off the RCA) is sometimes called the ….

A

Posterior interventricular artery

74
Q

In some cases, a third branch of the Left Coronary Artery can form, what is this called (2 names)

A

Ramus Intermedius
or.
Diagonal branch

75
Q

3 branches of the left anterior descending artery

A

L, R, & Inter-

ventricular branches

76
Q

2 branches of the left circumflex artery

A

left ventricle branch

left posterolateral branch

77
Q

What does PDA stand for?

What is it?

What does ‘Dominance’ have to do with PDA?

How much of the population is Right dominant vs Left vs . codominant ?

A

Patent Ductus Arterious

A heart anomaly. Abnormal opening between aorta and pulmonary artery

Dominance refers to the location/ source of the opening

85% - Right dominant
8% left dominant
7% codominant

78
Q

Describe the blood supply/ anatomy of the Patent Ductus Arterious in a patient with codominant anatomy

A

blood supply comes from RCA

Left posterior ventricular branches come from the LCX

79
Q

Where does the Patent Ductus Arterious branch from in Right and left dominant patients

A

Right dominant - branches from RCA

Left Dominant- branches from LCX

80
Q

Main controlling factor of a coronary CTA is what

A

heart rate

81
Q

what heart rate range yields optimal results for coronary CTA

A

65- 70 bpm

82
Q

What technical attributes of MDCT scanners allow for a coronary CTA to happen

A
  • increase temporal resolution
  • increase spatial resolution
  • synchronization of ECG waves
83
Q

indications for CCTA

A
  • coronary stenosis
  • coronary abnormalities
  • evaluation of coronary grafts or stents
84
Q

Current CT systems have gantry rotation times as fast as….

A

0.25 seconds

85
Q

An absolute contraindication for a CCTA

A

Patient not allowed to have IV contrast

86
Q

Relative contraindications to CCTA

A
  • arrhythmia
  • tachycardia
  • dense calcified coronary plaques
  • cant take B-Blockers
87
Q

What is temporal resolution in relation to Cardiac scans

A

When the MDCT system can freeze heart motion / vascular motion

88
Q

What is gantry rotation time

A

a parameter that controls the CT’s temporal resolution

ie.. rotation time of 200msec = temporal resolution of 200 msec

89
Q

What nifty reconstruction techniques do MDCT scanners employ to achieve temporal resolution below 100msec (hint: 4 ways)

A
  1. half scan reconstruction
  2. multi segment reconstruction
  3. Two-segment reconstruction
  4. Four segment reconstruction
90
Q

What happens during Half scan reconstruction ?

how does it affect temporal resolution?

A

data from half of the gantry rotation is used

splits resolution time in half
temporal resolution = 1/2 gantry rotation time

91
Q

What happens during multi segment reconstruction

A

combines data from multiple heartbeats to form image equaling 180 degrees of acquisition

92
Q

What happens during two segment reconstruction

A

2 heart beats used for single axial image

93
Q

What happens during four segment reconstruction

How does it affect temporal resolution ?

Beneficial to which type of patients

A

4 heart beats used to form images ( 45 degrees of data per cycle)

reduces temporal resolution by factor of 4

those with heart rates >100bpm

94
Q

With each half rotation of a dual source ct system temporal resolution can be reduced by what

A

up to a quarter

95
Q

What are the 2 main components of spatial resolution ?

A

in plain resolution

z axis resolution

96
Q

Whats the difference between in plain resolution and z-axisr

A

in plain resolution: controlled by factors related to x and y axis

z axis resolution:
controlled by detector width

97
Q

What can you administer to improve spatial resolution ?

How does it work?

A

nitro glycerin

dilates coronary vessels

98
Q

What part of the cardiac cycle is coronary artery/ heart wall motion the slowest ?

A

ventricular diastole

99
Q

T/F . the R-R interval only corresponds to a small part of the cardiac cycle

A

F.

Corresponds to all

100
Q

By selecting the phase percentage of the RR interval how is this helping the image?

Why does the percentage vary?

Around what percentage of the R-R interval is there normally the least heart motion ?

A

reduces motion artifact which increases the quality of the image

percentage varies based on patients heart rate

55- 75 %

101
Q

T/F. Prospective gating is a good way to evaluate heart function

A

False

its not good because it only acquires data during one portion of the cardiac cycle

102
Q

The main benefit of prospective ECG gating is the reduction of what percentage of radiation dose?

A

70%

103
Q

What is the preferred method for timing the administration of contrast in a CCTA

A

system bolus tracking software ( ROI trigger @ ascending aorta)

104
Q

What rate should you inject contrast for a CCTA?
What volume?
What types can be used?

A

4-6 mL/ sec

100mL

Ionic and Non ionic

105
Q

What type of reconstruction images are used to evaluate narrowing in coronary arteries

A

MPR

curved reformmated

106
Q

What equation yields 4 dimensional evaluation

A

x-axes + y-axes + z- axes + time = 4D

107
Q

Besides looking at coronary arteries , retrospective gating can asses these 4 things

A
  1. morphology of heart
  2. perfusion of heart
  3. ventricle volume and EF
  4. Wall thickness and motion abnormalities
108
Q

Describe a “multiphase data set” when it comes to heart CT

What loop is used to view this? From what stage to what stage?

A

Collection of data through the entire cardiac cycle so you can asses heart function

Cine loop

Systole –> diastole

109
Q

What pathologies can no coronary artery CTs identify?

A
  • Can differentiate between different masses in the heart

- pericardial disease

110
Q

what is the main usage for a CT angiogram of the aorta

A

evaluate aortic aneurysm

111
Q

How does an aortic dissection occur?

What are the two typed? Describe

A

When an inner layer of the aorta tears and a false opening is created

Stanford Type A- lesion in ascending aorta
Stanford Type B - lesion in descending aorta

112
Q

What is the scan coverage for a CTA of the Aorta ( from what to what?)

If needed coverage can extend past where?

A

base of neck –> celiac trunk

superiorly to carotid arteries or inferiorly to iliac bifurcation

113
Q

Guiding principle for contrast administration

A

bolus should last through entire scan but not past it

114
Q

CTA of Aorta

  • What is the recommended flow rate?
  • What’s the typical range in contrast volume administered for this scan?
  • Where is the ideal site to place the IV for this scan ? Why?
A

4-5 ml/ sec

75- 125 mL

Right AC. eliminates streaking artifact from contarst build up in aorta

115
Q

What technique can be used to eliminate pulsating artifact in the ascending aorta ?

A

retrospective gating

116
Q

Describe the “triple rule out” procedure ?

Name 3 considerations for this methodeno

A

chest evaluation for cardiac and non cardiac pain

  1. CCTA for coronary artery disease
  2. CTA of Aorta for aneurysm
  3. CTA of pulmonary artery for blood clots
117
Q

CT bronchography shows a 3D representation of what structure ? It may also include what types of views

A

tracheobronchial tree

endobronchial views (fly through views ) or virtual bronchoscopy

118
Q

Indications for CT bronchoscopy

A
  • narrowing air way
  • aspiration by foreign body
  • trauma
  • anatomical variant
  • stent plan/ eval
  • carcinoma
  • interventional guidance

Mosby CT review (8 decks)

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