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
2
Q
What is the key factor of helical scanning that makes scanning the chest in an entire breath hold possible
A
speed
3
Q
What is the purpose of having the patient hold their breath during a chest CT
A
creates motion free images
eliminates artifacts
4
Q
MDCT vs. SSCT scanners allow for these 3 technical improvements
A
- better differentiation of pulmonary nodules
- high quality MPR techniques
- simultaneous high resolution imaging
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
6
Q
How should the patient be positioned during a chest CT
A
supine
arms above the head
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
8
Q
What field of view is needed to acquire a chest CT ( structure A–> B)
A
above lung apices to costophrenic angles
9
Q
What forms the costophrenic angles
A
the points at which the chest wall and diaphragm meet.
10
Q
Low dose chest CTs are particularly important in these two populations
A
children
pregnant women
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)
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
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
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
15
Q
yes/ no . Does the chest already have inherent contrast to it to which sometimes IV contrast is un necessary?
A
yes
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
17
Q
Indications for a chest Ct WITH Contrast :
A
- mediastinum & vasculature evaluation
- lung/ hila abnormalities
- disease in chest lymph nodes
- CTA
18
Q
True/ False. Every vessel in the chest gets the same delay time
A
false. time is vessel dependent
19
Q
What should the injection rate range from when injection contrast in the chest
A
2.5- 4 mL/ sec
20
Q
True/ false. Superior vena cava typically has a low iodine concentration
A
false. High
21
Q
2 ways to avoid an artifact in the mediastinum when doing a chest CT with contrast
A
- dilute contrast media [C] with saline. Bolus inject it
2. image inferior to superior
22
Q
what can be used to see the esophagus better on a chest CT
A
oral barium sulfate
23
Q
What technique is applied to show diffuse lung disease
A
High resolution CT
HRCT
24
Q
What parameters maximize resolution in HRCT scanning
A
- high spatial frequency kernel
- axial thins ( 0.6- 2 mm)
- reduced DFOV
25
indications for HRCT chest CT
```
Bronchitis
emphysema
asthma
cystic fibrosis
COPD
```
26
True/ False . Image spacing in an HRCT slice decreases
false.
| increases
27
data acquisition for a HRCT of chest occurs when during the breathing cycle
What does forced expiration show us when scanning ?
when they cease breathing after a full inspiration
air trapping in small airway disease
28
how can prone positioning of the patient help with diagnosis vs having them regularly laying on their back
differentiates between the edema based changes seen in the chest at the base of the lungs
29
What retrospective reconstructive techniques can be a good substitute for HRCT images
reconstructing an image with a target DFOV, high resolution kernal , and 0.6mm width DFOV
30
What is the min-IP technique?
[Minimum intensity projection technique]
where the pixels that appear on the screen represent the minimum attenuation value on each ray
31
What two techniques can demonstrate air trapping in the patients lungs
imaging them at forced expiration
minimum intensity projection techniques
32
Whats the difference between a regular PE and a saddle PE ?
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
33
What is the Valsalva effect
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)
34
What does CTPA stand for?
Why do we acquire this scan caudocranial?
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
35
What rate do we inject for a CTPA?
What range in volume is acceptable for contrast administration for a CTPA ?
4-5 mL./ sec via 18 or 20 G catheter
80- 150 mL
36
What type of contrast could be used to increase patient comfort during a CTPA?
Pushing an extra saline flush can help the image how?
low-osmolar or iso-molar
1. rids the remaining saline from tubing/ peripheral veins
2. improves contrast visualization
3. decrease nephrotoxicity
37
How can ECG gating benefit a cardiac CT
eliminates pulsing artifacts caused by heart motion
38
what's the difference between prospective gating and retrospective gating?
Prospective gating: syncs data acquisition with the cardiac cycle. Data acquired only at diastole
Retrospective Gating: data acquisition occurs through entire cardiac cycle
39
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?
2- 3 min
same field of view + iliac crest to ankles
40
What does CTV stand for?
How do CTVs aid in differential diagnosis?
CT Venography
identifies deep vein blood clots
41
What does the "CAC" in CAC quantitation stand for ?
What does CCTA stand for ?
Coronary artery calcium
Coronary CTA
42
What does CAC quantitation tell us ?
In what was is this study limited? what can it not evaluate?
- 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
43
At what stage of a cardiac CTA is CAC quantitation employed
as a pre contrast component of a cardiac CTA
44
Describe the prospective gating approach using MDCT scanning in CAC quantitation
1. scan in diastole while monitoring ECG rhythm
| 2. percentage of the R-R interval will trigger data acquisition during the T wave
45
What is the Agatston Scoring system?
True/ False. The scoring system remains the same regardless of gender or age
- system that measures the volume and density of calcium within coronary arteries
false. Changes based on age and gender
46
Based on the Agatston scoring system, areas of calcium deposits are those that are greater than what mm-squared? Greater than what HU?
> 1 mm-squared
>130 HU
47
List the ranges that correspond with the following coronary artery calcium grades
- minimum
- mild
- moderate
- extensive
minimum 1-10
mild 11- 100
moderate 101-400
extensive >400
48
Fill in the blank.
| Sequential _____ images, sharing the same border, are acquired from ________ to _____________.
1. axial
2. aortic arch
3. base of heart
49
True/ False. Patients with elevated heart rates are typically put on beta blockers before getting a CAC study
False.
50
To avoid valsalva effect during a CTPA scan when should the data acquisition occur?
During shallow breathing
51
2 reasons why a CTPA scan be acquired in a caudocranial direction
incase patient cant hold their breath for the entire length of the scan
less streaking artifact from SVC
52
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
- 80 to 150 mL
- 4-5 mL/sec
- 18 or 20 gauge
- low-osmolar or iso-molar
53
Why does injecting saline after contrast administration prove beneficial
gets all contrast out of IV tubing and peripheral; vessels
increases contrast enhancement
decreases nephrotoxicity
reduces artifact created from dense contrast
54
How does incorporating ECG gating aid in a cardiac scan?
eliminates pulsating artifact caused by heart motion
55
what's the difference between prospective gating and retrospective gating?
Prospective gating: syncs data acquisition with the cardiac cycle. Data acquired only at diastole
Retrospective Gating: data acquisition occurs through entire cardiac cycle
56
What does CAC and CCTA stand for ?
What is the indication for a CAC scan
Coronary Artery Calcium
Coronary CTA
[indication]: athersclerotic disease
57
CAC quantitation measures what?
In what way is this study limited ?
calcified atherosclerotic plaque
Does not account for non calcified plaques
58
Describe the prospective gating approach for data acquisition
How does it benefit the patient
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
what component of a cardiac CTA is CAC quantitation employed
pre contrast component
60
What does the Agatson scoring system tell us?
the density of calcium deposits in coronary arteries.
61
True/ False.
| The Agatson score remains constant regardless of a patients age or gender
false. changes based on age and gender
62
List the appropriate ranges for each of the grades for CAC scoring
- minimal
- mild
- moderate
- extensive
- minimal (1-10)
- mild (11-100)
- moderate (101- 400)
- extensive (>400)
63
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?
-False
low dose , cine- axial -acquisition
- aortic arch--->base of heart
64
Why are CAC studies typically subject to motion artifact ?
How so some CT systems eliminate this artifact ?
patents who have elevated heart rates are usually imaged without the administration of a beta
take multiple axial images within set time intervals
65
T/F. Calcium, mass and agatson score are already tracked within CT software
T
66
What benefit does dual energy MDCT technology offer when scanning
how does it help in CAC scanning
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
Which scan looks at the arterial blood flow through the heart
Coronary CTA
| CCTA
68
What comprises the coronary arteries and where does it arise from ?
Left and right Coronary artery arise from the aorta
69
How many branches stem off the Right coronary artery (RCA)
6
70
How many branches stem off the Left coronary artery (LCA)
2
71
Name the branches coming off the RCA
| Hint: Trace your nose. Arteries sound like the position of these structures
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
Name the branches coming off the LCA
Left Anterior descending
| Left Circumflex
73
The posterior descending artery ( branching off the RCA) is sometimes called the ....
Posterior interventricular artery
74
In some cases, a third branch of the Left Coronary Artery can form, what is this called (2 names)
Ramus Intermedius
or.
Diagonal branch
75
3 branches of the left anterior descending artery
L, R, & Inter-
| ventricular branches
76
2 branches of the left circumflex artery
left ventricle branch
| left posterolateral branch
77
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 ?
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
Describe the blood supply/ anatomy of the Patent Ductus Arterious in a patient with codominant anatomy
blood supply comes from RCA
Left posterior ventricular branches come from the LCX
79
Where does the Patent Ductus Arterious branch from in Right and left dominant patients
Right dominant - branches from RCA
Left Dominant- branches from LCX
80
Main controlling factor of a coronary CTA is what
heart rate
81
what heart rate range yields optimal results for coronary CTA
65- 70 bpm
82
What technical attributes of MDCT scanners allow for a coronary CTA to happen
- increase temporal resolution
- increase spatial resolution
- synchronization of ECG waves
83
indications for CCTA
- coronary stenosis
- coronary abnormalities
- evaluation of coronary grafts or stents
84
Current CT systems have gantry rotation times as fast as....
0.25 seconds
85
An absolute contraindication for a CCTA
Patient not allowed to have IV contrast
86
Relative contraindications to CCTA
- arrhythmia
- tachycardia
- dense calcified coronary plaques
- cant take B-Blockers
87
What is temporal resolution in relation to Cardiac scans
When the MDCT system can freeze heart motion / vascular motion
88
What is gantry rotation time
a parameter that controls the CT's temporal resolution
ie.. rotation time of 200msec = temporal resolution of 200 msec
89
What nifty reconstruction techniques do MDCT scanners employ to achieve temporal resolution below 100msec (hint: 4 ways)
1. half scan reconstruction
2. multi segment reconstruction
3. Two-segment reconstruction
4. Four segment reconstruction
90
What happens during Half scan reconstruction ?
how does it affect temporal resolution?
data from half of the gantry rotation is used
| splits resolution time in half
temporal resolution = 1/2 gantry rotation time
91
What happens during multi segment reconstruction
combines data from multiple heartbeats to form image equaling 180 degrees of acquisition
92
What happens during two segment reconstruction
2 heart beats used for single axial image
93
What happens during four segment reconstruction
How does it affect temporal resolution ?
Beneficial to which type of patients
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
With each half rotation of a dual source ct system temporal resolution can be reduced by what
up to a quarter
95
What are the 2 main components of spatial resolution ?
in plain resolution
z axis resolution
96
Whats the difference between in plain resolution and z-axisr
in plain resolution: controlled by factors related to x and y axis
z axis resolution:
controlled by detector width
97
What can you administer to improve spatial resolution ?
| How does it work?
nitro glycerin
| dilates coronary vessels
98
What part of the cardiac cycle is coronary artery/ heart wall motion the slowest ?
ventricular diastole
99
T/F . the R-R interval only corresponds to a small part of the cardiac cycle
F.
Corresponds to all
100
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 ?
reduces motion artifact which increases the quality of the image
percentage varies based on patients heart rate
55- 75 %
101
T/F. Prospective gating is a good way to evaluate heart function
False
its not good because it only acquires data during one portion of the cardiac cycle
102
The main benefit of prospective ECG gating is the reduction of what percentage of radiation dose?
70%
103
What is the preferred method for timing the administration of contrast in a CCTA
system bolus tracking software ( ROI trigger @ ascending aorta)
104
What rate should you inject contrast for a CCTA?
What volume?
What types can be used?
4-6 mL/ sec
100mL
Ionic and Non ionic
105
What type of reconstruction images are used to evaluate narrowing in coronary arteries
MPR
| curved reformmated
106
What equation yields 4 dimensional evaluation
x-axes + y-axes + z- axes + time = 4D
107
Besides looking at coronary arteries , retrospective gating can asses these 4 things
1. morphology of heart
2. perfusion of heart
3. ventricle volume and EF
4. Wall thickness and motion abnormalities
108
Describe a "multiphase data set" when it comes to heart CT
| What loop is used to view this? From what stage to what stage?
Collection of data through the entire cardiac cycle so you can asses heart function
Cine loop
Systole --> diastole
109
What pathologies can no coronary artery CTs identify?
- Can differentiate between different masses in the heart
| - pericardial disease
110
what is the main usage for a CT angiogram of the aorta
evaluate aortic aneurysm
111
How does an aortic dissection occur?
| What are the two typed? Describe
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
What is the scan coverage for a CTA of the Aorta ( from what to what?)
If needed coverage can extend past where?
base of neck --> celiac trunk
superiorly to carotid arteries or inferiorly to iliac bifurcation
113
Guiding principle for contrast administration
bolus should last through entire scan but not past it
114
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?
4-5 ml/ sec
75- 125 mL
Right AC. eliminates streaking artifact from contarst build up in aorta
115
What technique can be used to eliminate pulsating artifact in the ascending aorta ?
retrospective gating
116
Describe the "triple rule out" procedure ?
| Name 3 considerations for this methodeno
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
CT bronchography shows a 3D representation of what structure ? It may also include what types of views
tracheobronchial tree
endobronchial views (fly through views ) or virtual bronchoscopy
118
Indications for CT bronchoscopy
- narrowing air way
- aspiration by foreign body
- trauma
- anatomical variant
- stent plan/ eval
- carcinoma
- interventional guidance
