Procedures- Brain And Contrast Media Flashcards
What are three indications of IV iodinated contrast media for a head scan?
Neoplasm
Inflammatory processes
Vascular abnormalities
Administering iodinated contrast raises the attenuation value of what anatomical structure while increasing contrast and CT visualization
Brain gray matter
What is an example of pathology in the blood-brain barrier that contrast enhances when administered?
Intracranial neoplasm
What is an average range of nonionic contrast media given for a CT of the head?
75-150mL
What is the amount of contrast media dependent on?
Study type, patient weight, and renal function
What is a typical range for injection rates of contrast media for a CT head?
1-4mL/sec
What types of exams would contrast be injected at 4mL/sec for a CT of the head?
CT angiography or perfusion studies
How long can scan delays be for a CT head scan to rule out a neoplasm?
Up to ~5min
What is an example of a general protocol for a head scan with contrast?
100mL of nonionic CM, 1-3 mL/sec, and 60 second scan delay
What does a CTA brain scan look at?
Cranial blood vessels (circle of Willis)
What are the vessels involved in the COW?
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
What are two vessels that are not part of the COW but important to CTA imaging?
Basilar artery and middle cerebral arteries
What pathology is diagnosed with a CTA brain scan?
Cerebral aneurysm, intracranial thrombosis, traumatic cerebrovascular injury, arteriovenous malformation, and stenosis
What type of slice thickness and scan acquisition is used for a CTA brain?
Thin-section (0.5-1.5mm) and helical
What direction is a CTA brain scanned?
Caudicranial
What is the scan range for a CTA brain?
C2- 1cm above the dorsal sella
And through the vertex for a 16-slice or higher
What is performed before the contrast is administered to evaluate anatomy and pathology?
Survey scan
At what rate is contrast injected for a CTA spiral acquisition during rapid bolus?
3-4mL/sec
What’s the empiric delay for a CTA spiral acquisition?
12-20seconds
What’s a way the proper delay time can be determined?
Visually identifying the time at which peak vessel enhancement occurs
At what point is a scan automatically triggered during a contrast scan?
Once a predetermined HU is reached in a vessel
At what percentage is a thin section of a CTA brain reconstructed for maximizing the quality of MPR and 3D images?
50%
What planes are axial source images reformatted into?
Coronal, sagittal and oblique
What types of 3D techniques are employed for a CTA brain?
MIP, surface rendering, and volume rendering
What is the amount of contrast given and at what rate for a COW CTA study on a 64-slice scanner?
50-75mL of nonionic contrast at 4mL/sec
What is the scan delay range for a CTA COW study on a 64-slice scanner?
15-20seconds
What collimation dimension is used for a CTA COW on a 64-slice helical scanner?
0.625mm
What kvp and mAs range is used for a CTA COW study on a 64-slice scanner?
80-120kVp
300mA/0.4sec
How much overlap is required to reformat images from a CTA COW study into coronal and sagittal MPR, MIP and volume-rendered 3D images?
0.75mm
What vessels are included in a stroke evaluation CTA acquisition?
Intracranial and extracranial
What special technique can be used on CTA source images to evaluate acute brain infarct?
Subtraction maps
What is the protocol for an acute stroke procedure?
Precontrast head
CTA of brain and carotid arteries
CT Perfusion
Term that refers to the level of blood flow throughout brain tissue
Cerebral perfusion
What is used to evaluate the initial passing of iodinated CM through the vasculature of the brain?
CT perfusion
What determines the quantity of blood in mL that is contained within a 100-g volume of brain tissue
Cerebral blood volume
What is the normal range of cerebral blood volume?
4-5mL/100g of tissue
The quantity of blood that moves through 100g of brain tissue each minute?
Cerebral blood flow
What is the normal range of CBF in gray matter?
50-60mL/100g/min
What is the average transit time, in seconds, for blood to pass through a given region of brain tissue?
Mean transit time
What varies according to the distance traveled between arterial inflow and venous outflow for a particular area?
Mean transit time
What is the formula for cerebral blood flow?
CBF= CBV/MTT
What is the primary indication for a CT perfusion?
Acute stroke
What’s the primary goal of CTP?
Identify and differentiate the infarct core and penumbra
What part of the brain tissue during a stroke is considered non-repairable for thrombotic therapy?
Infarct core
What tissue is considered the ischemic yet still viable tissue immediately surrounding the infarct core?
Penumbra
What percentage of blood flow decrease is shown in ischemic tissue as compared with normal brain tissue?
34%
The penumbra region of ischemic brain parenchyma can still have a CBV greater than what range?
2.5mL/100g
What range of CBV within the brain parenchyma marks brain tissue as the infarct core?
Less than 2.5mL/100g
CTP imaging of the brain generates maps of what values and what do they help distinguish?
CBF, CBV, and MTT
Regions of ischemic penumbra from infarct core
A bolus of how much contrast and at what rate is used for a CTP brain study?
50mL @ 4-7mL/sec
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?
Cine
What is placed over a well-opacified artery and an area of venous outflow?
Region of interest (ROI)
What are examples of vessels where an ROI may be placed in the brain?
Anterior cerebral artery and superior sagittal sinus
What is the mathematical technique utilized for generation of perfusion maps?
Deconvolution
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?
Xenon CT Perfusion
