Chapter 7. Guidelines in Neuroimaging in Stroke Flashcards
What is the reason of hyperdensity in NCCT
due to increase protein due to clot retraction from globin particle
5 Early signs of ischemia in NCCT
- Hyperdense MCA “dot sign”
- Obscuration of lentiform nucleus
- Loss of gray white matter differentiation
- Insular Ribbon Sign
- Sulcal Effacement
What is the explanation of presence of obscuration of lentiform nucleus in acute ischemia
Failure of ion pump to maintain cellular homeostasis causing influx of water
What is the explanation of presence of Hyperdense MCA sign in acute ischemia
Clot retraction
What is the least sensitive in early signs in NCCT
Hyperdense MCA sign
This is define as average time it takes to transit through a volume of brain
Mean transit time
This represent the altered area of the brain risk for infarction
Cerebral blood flow
What represents the penumbra
MTT
Penumbra is defined as
Increased MTT
Decreased CBF
Normal to mildly elevated CBV
Infarcted tissue
Decreased CBF and CBV
Increased MTT
CT technique where it is able to identify the core of infarct
CTA source imaging (CTA-SI)
This is a 10 point quantitative CT that determine infarct core volume
ASPECTS
This is based on restricted diffusion of water molecule as a result of movement of extracellular water into intracellular compartment
Diffusion weighted imaging
This is a random movement of water
Brownian Motion
The image protocol and creating image of human anatomy is using this method
Pulse Sequence
Depicts the area of restricted diffusion as low intensity signal
Apparent Diffusion Coefficient
Peak duration where ADC continues to decrease its intensity
3-5 days
What are the sequence in MRI important for dating infarcts
DWI
ADC
T2
This sequence is sensitive in detecting microbleeds in chronic hypertension
GRE
What does SWI provides additional information
Detect hemorrhage with in infarct
Areas of hypoperfusion
Acute thromboembolic occluding artery
What sequence helps to establish the age of infarct
T2 and T1
Sequence of hemoglobin metabolism in MRI
Hyperacute - OxyHgb
Acute - DeoxyHgb
Early Subacute - MethylHgb
Subacute-Chronic - Extracellular Hgb
Sequence of intensity of T1 from Acute - Chronic
Iso
Iso-Hyper
Hyper
Hyper
Sequence of intensity of T2 from Acute - Chronic
Hyper
Hypo
Hypo
Hyper
Remote bleeds will appear in T2 and T1 imaging
Hypointense
How many percent will give early signs of infarct in CT-scan during hyperacute stage
60%
