Week 4 Part 2 Flashcards
What does in vivo imaging allow for
Observation of the behaviour of single cells in the diseased nervous system
Provides insight into how neurological diseases emerge and how they can be treated
What does functional microscopy techniques allow?
E.g. Intrinsic optical imaging and calcium imaging
Allow measurement of neuronal activity in vivo
What does structural imaging provide?
Anatomical information of the brain
What is structural MRI?
- Non-invasive technique for examining the anatomy and pathology of the brain
- Produced images which can be used for clinical radiological reporting as well as for detailed analysis
What are the structural techniques?
- Cerebral angiography
- Computerised tomography
- MRI
- Diffusion MR imaging that
What is functional imaging?
Provides information of physiological processes that underscore neural activity
What are the functional techniques?
Functional magnetic resonance imaging
PET
SPECT
EEG and MEG
What is structural/anatomical changes MRI in neuro-oncology?
- Location
- Symmetry
- Surrounding tissues
What can signal in MR images be?
- High or low depending on pulse sequence used and type of tissue in the image region of interest
Dark in T1-weighted images
- Increased water as in Eden’s, tumor, infarcartion, inflammation, infection and hemorrhage
- Low proton density
3: flow void
Bright on T1-weighted image
- Fat
- Subacute hemorrhage
- Melanin
- Protein-rich fluid
- Slowly flowing blood
- Paramagnetic substance e.g. copper
- Calcification
- Laminar necrosis of cerebral infarction
Bright on T2-weighted image
Increased water
Methemoglobin in subacute hemorrhage
Dark on T2 weighted image
Low proton density
Protein rich fluid
Flow void
T1 weighted signal
Anatomical information based water content within tissue
T2 weighted signal
Reactive oedema in the adjacent white matter of brain
What does grey matter have?
10% more water than white matter and this creates a contrast
What is diffusion weighted imaging?
Is a form of MR imaging based upon measuring the random Brownian motion of water molecules within a vowel of tissue
Where is restricted diffusion seen?
- Abscesses
- Cysts
- Acute infarction
What does tumour have?
Low restricted diffusion
What does diffusion-weighted imaging has a major role in ?
Clinical situations
- early identification of ischaemic stroke
- Differentiation of acute from chronic stroke
- Differentiation of abscess from necrotic tumours
- Assessment of the extent of diffuse axonal injury
What is the purpose of contrast-enhanced CT?
- Find pathology by enhancing the contrast between a lesion and the normal surrounding structure
Why is contrast agent important?
It gives better resolution
What is 18F-FDG PET/CT?
Powerful imaging tool for the detection of various cancer
Staging and restaging of some tumours
Role in detection of recurrence in asymptomatic patients
What is the goal of imaging in a patient with acute stroke ?
- Exclude hemorrhage
- Differentiate between irreversibly and reversible impaired tissue
- Identify occlusion of major extra and intracranial arteries
What is the advantage of CT?
Available 24 hours a day
Gold standard for haemorrhage
What is the overall sensitivity and specificity of CT to diagnose stroke?
Sensitivity - 64%
Specificity - 85%
What is the reason we see ischemia on CT?
Cytotoxic Edema develops as a result of failure of the ion-pumps
Due to inadequate supply of ATP
Hypodensity on CT
Irreversible ischemic brain damage
What will result in a CT attenuation decrease of 2.5 HU?
An increase of brain water content by 1%
What is the most sensitive sequence for stroke imaging,
DWI
What is Multiple Sclerosis (MS)?
CNS condition in which the myelin is damaged
What are the symptoms of MS?
- Inflammation
- Demyelination
- Gliosis (inflammation)
- Axonal injury
