Imaging Brain Structure & Function

• What is CT?

  Computed tomography

  X-rays are passed through the patient & relative rate of absorbance is measure by a detector

  Different tissues absorb/attenuate different amounts of radiation
• T1 & T2 are NOT opposites.
• Fill in the blanks

  A) Brain

  B) Subdural

  C) Stroke

  D) Soft tissue

  E) Bone

  
• In CT, you have to select to correct 'window' in order to identify what you would like.

  E.g. if you suspect a fracture, using the bone windows

  
  

  Also have to choose the correct algorithm.
• Fill in the blanks

  A) T1

  B) T2

  
• What colour is CSF in T1?

  Black
• What colour is CSF in T2?

  White
• What colour is grey matter in T1?

  Dark grey
• What colour us white matter in T1?


  Light grey
• What colour is white matter in T2?

  Dark grey
• What colour is grey matter in T2?

  Light grey
• What are the different things that can be done to alter MRIs?

  Weighting

  • T1 weighted (A)
  • T2 weighted (C)
  • Proton densory axial (weighted for neither T1 or T2) (B)

  Tracer (Gadolinium)

  • enhances signal in fluid (handy for oedema/blockage/haemorrhage) (D)

  FLAIR (FLuid Attenuated Inversion Recovery)

  • extra radio pulse to maniuplate signal -> cancels out signal of CSF (E)

  Diffusion-Wieghted Image (DWI)

  • extra magnetic gradients applied to either side of radio pulses
  • great for spotting ischaemia (F)

  
• What is EEG?


  Electroencephalography
• What does EEG involved?


  Recording through the scalp of the electrical potentials that accompany activity in the cortex
• What information can an EEG give?

  Can provide important real-time information about brain activity
• What is PET?

  Postiron emission tomography

  Radioactive 'tracer' molecule introducted to patient & visualised in PET scanner

  Used to visualise cortical function (particular aspects of structure based on a molecule e.g. DaT Scan in PD for dopamine)

  
• What is the thing that defines the human brain?

  The massive amount of association cortex

  Cortex containing neuronal circuits that connect to other areas
• What is the function of Broca's area?

  Language production/speech
• What is the function of the frontal eye field?

  Eye movements
• The prefrontal cortex & cingulate are the regions the most associated with executive function (decision-making area)
• The human pre-frontal cortex is massive.
• What is fMRI?

  Functional MRI

  Measures the decay os oxyhaemoglobin -> blood flow is highly correlated with brain activity -> measures brain activity