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Mosby's Exam Review > Procedures- Brain And Contrast Media > Flashcards

Procedures- Brain And Contrast Media Flashcards

1
Q

What are three indications of IV iodinated contrast media for a head scan?

A

Neoplasm
Inflammatory processes
Vascular abnormalities

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2
Q

Administering iodinated contrast raises the attenuation value of what anatomical structure while increasing contrast and CT visualization

A

Brain gray matter

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3
Q

What is an example of pathology in the blood-brain barrier that contrast enhances when administered?

A

Intracranial neoplasm

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4
Q

What is an average range of nonionic contrast media given for a CT of the head?

A

75-150mL

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5
Q

What is the amount of contrast media dependent on?

A

Study type, patient weight, and renal function

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6
Q

What is a typical range for injection rates of contrast media for a CT head?

A

1-4mL/sec

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7
Q

What types of exams would contrast be injected at 4mL/sec for a CT of the head?

A

CT angiography or perfusion studies

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8
Q

How long can scan delays be for a CT head scan to rule out a neoplasm?

A

Up to ~5min

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9
Q

What is an example of a general protocol for a head scan with contrast?

A

100mL of nonionic CM, 1-3 mL/sec, and 60 second scan delay

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10
Q

What does a CTA brain scan look at?

A

Cranial blood vessels (circle of Willis)

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11
Q

What are the vessels involved in the COW?

A

Right and left anterior cerebral arteries
Anterior communicating artery
Right and left internal carotid arteries
Right and left posterior cerebral arteries
Right and left posterior communicating arteries

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12
Q

What are two vessels that are not part of the COW but important to CTA imaging?

A

Basilar artery and middle cerebral arteries

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13
Q

What pathology is diagnosed with a CTA brain scan?

A

Cerebral aneurysm, intracranial thrombosis, traumatic cerebrovascular injury, arteriovenous malformation, and stenosis

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14
Q

What type of slice thickness and scan acquisition is used for a CTA brain?

A

Thin-section (0.5-1.5mm) and helical

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15
Q

What direction is a CTA brain scanned?

A

Caudicranial

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16
Q

What is the scan range for a CTA brain?

A

C2- 1cm above the dorsal sella

And through the vertex for a 16-slice or higher

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17
Q

What is performed before the contrast is administered to evaluate anatomy and pathology?

A

Survey scan

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18
Q

At what rate is contrast injected for a CTA spiral acquisition during rapid bolus?

A

3-4mL/sec

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19
Q

What’s the empiric delay for a CTA spiral acquisition?

A

12-20seconds

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20
Q

What’s a way the proper delay time can be determined?

A

Visually identifying the time at which peak vessel enhancement occurs

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21
Q

At what point is a scan automatically triggered during a contrast scan?

A

Once a predetermined HU is reached in a vessel

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22
Q

At what percentage is a thin section of a CTA brain reconstructed for maximizing the quality of MPR and 3D images?

A

50%

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23
Q

What planes are axial source images reformatted into?

A

Coronal, sagittal and oblique

24
Q

What types of 3D techniques are employed for a CTA brain?

A

MIP, surface rendering, and volume rendering

25
Q

What is the amount of contrast given and at what rate for a COW CTA study on a 64-slice scanner?

A

50-75mL of nonionic contrast at 4mL/sec

26
Q

What is the scan delay range for a CTA COW study on a 64-slice scanner?

A

15-20seconds

27
Q

What collimation dimension is used for a CTA COW on a 64-slice helical scanner?

A

0.625mm

28
Q

What kvp and mAs range is used for a CTA COW study on a 64-slice scanner?

A

80-120kVp

300mA/0.4sec

29
Q

How much overlap is required to reformat images from a CTA COW study into coronal and sagittal MPR, MIP and volume-rendered 3D images?

A

0.75mm

30
Q

What vessels are included in a stroke evaluation CTA acquisition?

A

Intracranial and extracranial

31
Q

What special technique can be used on CTA source images to evaluate acute brain infarct?

A

Subtraction maps

32
Q

What is the protocol for an acute stroke procedure?

A

Precontrast head
CTA of brain and carotid arteries
CT Perfusion

33
Q

Term that refers to the level of blood flow throughout brain tissue

A

Cerebral perfusion

34
Q

What is used to evaluate the initial passing of iodinated CM through the vasculature of the brain?

A

CT perfusion

35
Q

What determines the quantity of blood in mL that is contained within a 100-g volume of brain tissue

A

Cerebral blood volume

36
Q

What is the normal range of cerebral blood volume?

A

4-5mL/100g of tissue

37
Q

The quantity of blood that moves through 100g of brain tissue each minute?

A

Cerebral blood flow

38
Q

What is the normal range of CBF in gray matter?

A

50-60mL/100g/min

39
Q

What is the average transit time, in seconds, for blood to pass through a given region of brain tissue?

A

Mean transit time

40
Q

What varies according to the distance traveled between arterial inflow and venous outflow for a particular area?

A

Mean transit time

41
Q

What is the formula for cerebral blood flow?

A

CBF= CBV/MTT

42
Q

What is the primary indication for a CT perfusion?

A

Acute stroke

43
Q

What’s the primary goal of CTP?

A

Identify and differentiate the infarct core and penumbra

44
Q

What part of the brain tissue during a stroke is considered non-repairable for thrombotic therapy?

A

Infarct core

45
Q

What tissue is considered the ischemic yet still viable tissue immediately surrounding the infarct core?

A

Penumbra

46
Q

What percentage of blood flow decrease is shown in ischemic tissue as compared with normal brain tissue?

A

34%

47
Q

The penumbra region of ischemic brain parenchyma can still have a CBV greater than what range?

A

2.5mL/100g

48
Q

What range of CBV within the brain parenchyma marks brain tissue as the infarct core?

A

Less than 2.5mL/100g

49
Q

CTP imaging of the brain generates maps of what values and what do they help distinguish?

A

CBF, CBV, and MTT

Regions of ischemic penumbra from infarct core

50
Q

A bolus of how much contrast and at what rate is used for a CTP brain study?

A

50mL @ 4-7mL/sec

51
Q

What acquisition of at least 2cm of brain region over a period of 45-69 seconds is used for tracking the first pass of contrast agent through the intracranial vasculature?

A

Cine

52
Q

What is placed over a well-opacified artery and an area of venous outflow?

A

Region of interest (ROI)

53
Q

What are examples of vessels where an ROI may be placed in the brain?

A

Anterior cerebral artery and superior sagittal sinus

54
Q

What is the mathematical technique utilized for generation of perfusion maps?

A

Deconvolution

55
Q

What is performed with inhalation of nonradioactive isotope of xenon gas that enters the bloodstream and can be used to calculate a brain map on basis of CBF?

A

Xenon CT Perfusion

Mosby's Exam Review (18 decks)

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