Summary Neurological and Psychiatric Disorders (AB_1023)
19 vues 0 fois vendu
Cours
Neurological and Psychiatric Disorders (AB_1023)
Établissement
Vrije Universiteit Amsterdam (VU)
Complete summary of the course Neurological and Psychiatric Disorders (AB_1023) from the minor Biomedical Topics in Health Care, given at VU Amsterdam. This summary contains all information needed for the exam, and includes all the material from the lectures. This summary was made during my third y...
, Brain Imaging
NEUROIMAGING
- Why use it?
- Clinic
- Diagnosis/prognosis of neurological disorders
- CT, MRI, MRA, MRS, PET, X-ray
- Research
- Improve diagnostics of neurological disorders
- Prediction of disorders
- Understand biological processes (using advanced imaging techniques)
- Anatomical planes:
- Axial (transverse): separates upper and lower halves of the body
- Coronal: separates front and back of the body
- Sagittal: separates left and right sides of the body
STRUCTURAL BRAIN IMAGING
- Reasons for brain imaging:
- Identifying the e ects of a stroke
- Locating cysts and tumors
- Finding swelling and bleeding
- Disease-related lesions
- Common structural brain/skull imaging:
- X-ray: shows bone/skull only, not the brain
- Best used to detect bone fractures
- CT: shows brain, but not in great detail
- Shows presence of any larger bleed, stroke, lesions, or masses
- Quick test, so preferred during emergency
- Visually: worse resolution (more pixels), bones light up (skull appears white)
- MRI: shows brain in greater detail
- Shows presence of smaller bleeds, stroke, lesions, or masses
- Long test, so preferred with long-term symptoms
- Visually: better resolution, skull appears dark (due to little water contents of tissue), fat
on skull appears white
- Air and bone give no signals on an MRI scan, and therefore appear dark
- Magnetic Resonance Imaging (MRI):
- Strong magnetic eld, so magnetic materials have to be kept out of the room
- Magnetic eld is measured in Teslas
- Advantages of MRI:
- Non-invasive
- Non-ionizing radiation
- High soft-tissue resolution and discrimination between tissue types
- Morphological information as well as functional information
- Disadvantages of MRI:
- Time consuming
- Contraindications for MRI: patients that cannot be scanned due to e.g. presence of
pacemaker or surgical plates
- Loud noise
- Sequence needs to be adapted to question
- Sequence: di erent types of MRIs
- Technique behind MRI:
- MRI uses magnetism and radio frequency signals to acquire images
- MR images are based on density of protons
- 1) No magnet: hydrogen atoms (protons) in body are randomly positioned
- 2) Magnet on: most protons get aligned in the direction of the magnetic eld
- 3) Radio pulse: protons spin and move orthogonally
3
fi ff fffi fi
, - 4) Protons relax: release radio signal
- The time that it takes for the protons to return to their original position is
measured, resulting in di erent signals for di erent types of tissues
- Main ‘techniques’ in MRI:
- T1 weighted images:
- Contrasts fat/water
- Used to look at the anatomy/enhancement of the brain (e.g. atrophy, lesions)
- Visually: grey matter appears grey, white matter appears white
- T2 weighted images:
- Contrasts water/tissue
- Used to look at the pathology of the brain (e.g. edema)
- Visually: cerebrospinal uid appears white, grey matter appears light grey
- Tip: in T2 (tWo), Water (i.e. CSF) = White
- T1 vs. T2: what you want to see determines what sequence you will use
- T1 detects tumors more easily, whereas T2 detects edema more clearly
- Fluid-attenuated inversion recovery (FLAIR):
- T2 weighted MRI scan
- “Inversion Recovery”: CSF (i.e. white signal) is suppressed, thereby improving
contrast
- Easier to distinct the (entire) damaged area
- T1 vs. FLAIR:
- T1: neuroanatomical changes, therefore hard to see edema on T1 image
- FLAIR: changes related to water, therefore very obvious to see edema on T2
or FLAIR
- Double Inversion Recovery (DIR):
- T2 + FLAIR
- Suppress both CSF and white matter signal (i.e. fat tissue)
- Used to detect lesions/plaques in white matter, or between grey/white matter
- Magnetic Resonance Angiography (MRA):
- Can be used to detect arteriovenous malformation (AVM) and ischemic stroke
- AVM: abnormal connection between arteries and veins; usually asymptomatic
- Brain imaging in research:
- Qualitative
- Standard clinical practice
- Look for pathology
- Quantitative
- ‘Numbers’ as output
- Understand biological mechanisms
- Compare patient groups to healthy controls
- Di usion Tensor Imaging (DTI):
- MRI of how white matter tracts are connected (i.e. how the brain is ‘wired’)
- Tractography can show an overview of white matter connections
- Why does white matter matter?
- Alzheimer’s disease, Parkinson’s disease, multiple sclerosis, schizophrenia, etc.
- DTI is used to assess white matter integrity
- Healthy nerve: passage of nerve impulse
- Damaged nerve in MS (with areas of demyelation): interference in passage of nerve
impulse
- Technique behind DTI: the di usion of water molecules through axons is measured
- Isotropic: di usion is the same in every direction
- Anisotropic: di usion varies with direction
- 4 main di usion outcome parameters for microstructural integrity:
- Fractional anisotropy (FA): directionality of the water di usion
- Mean di usivity (MD): the average di usivity
- Axonal di usivity (AD): di usivity along the axon
- Radial di usivity (RD): di usivity perpendicular to the axon
4
ff
ffffffff ff ff fl ffffff ff ff ff ff
Les avantages d'acheter des résumés chez Stuvia:
Qualité garantie par les avis des clients
Les clients de Stuvia ont évalués plus de 700 000 résumés. C'est comme ça que vous savez que vous achetez les meilleurs documents.
L’achat facile et rapide
Vous pouvez payer rapidement avec iDeal, carte de crédit ou Stuvia-crédit pour les résumés. Il n'y a pas d'adhésion nécessaire.
Focus sur l’essentiel
Vos camarades écrivent eux-mêmes les notes d’étude, c’est pourquoi les documents sont toujours fiables et à jour. Cela garantit que vous arrivez rapidement au coeur du matériel.
Foire aux questions
Qu'est-ce que j'obtiens en achetant ce document ?
Vous obtenez un PDF, disponible immédiatement après votre achat. Le document acheté est accessible à tout moment, n'importe où et indéfiniment via votre profil.
Garantie de remboursement : comment ça marche ?
Notre garantie de satisfaction garantit que vous trouverez toujours un document d'étude qui vous convient. Vous remplissez un formulaire et notre équipe du service client s'occupe du reste.
Auprès de qui est-ce que j'achète ce résumé ?
Stuvia est une place de marché. Alors, vous n'achetez donc pas ce document chez nous, mais auprès du vendeur SummaryLin. Stuvia facilite les paiements au vendeur.
Est-ce que j'aurai un abonnement?
Non, vous n'achetez ce résumé que pour €9,99. Vous n'êtes lié à rien après votre achat.
