Applications of Magnetic Resonance Imaging (MRI) and Computed Tomography CT)

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Applications of Magnetic Resonance Imaging
(MRI) and Computed Tomography CT)

• Lecture 1
• F33AB5

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(No Transcript)
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What are CT and MRI?

• CT uses X-rays to produce tomographs (images of
  slices)
• MRI uses magnetic fields to probe the intrinsic
  magnetisation of hydrogen nuclei

http//www.mri-ny.com/scannersound.html
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Overview

• Advantages and problems of each technique
• Anatomical imaging
• Functional imaging

Phillips
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Problems of CT

• Dose (fluroscopy/dynamic mode not possible)
• (Speed- improving)
• (3D- now available using helical scanning)
• Artefacts behind bone

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Advantages of CT

• (Limited) soft tissue contrast
• Spatial measurements exact (if set up correctly)

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Problems of MRI

• Not for people who are claustrophobic
• Not for people with metal in their bodies
• Susceptibility differences (eg between air and
  tissue) cause distortions in most sequences,
  compromising surgical planning
• Can be slow (not EPI), can have motion artefacts
• Can be expensive (750k)

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Advantages of MRI

• Excellent (and controllable) soft tissue contrast
• Much functional information
• Steerable imaging planes
• Safe
• Hugely versatile

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Anatomical- CT

• Intracranial bleeds
• Radiotherapy planning
• low geometric distortion
• CT contrast relates to radiation attenuation
• Stereotactic surgery
• low geometric distortion
• Angiography

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Anatomical- CT
Chronic subdural haematoma

• Intracranial bleeds
• Radiotherapy planning
• low geometric distortion
• CT contrast relates to radiation attenuation
• Stereotactic surgery
• low geometric distortion
• Angiography

http//www.radiology.co.uk/xrayfile/xray/tutors/ct
trauma/tutor.htm
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Anatomical- CT

• Intracranial bleeds
• Radiotherapy planning
• low geometric distortion
• CT contrast relates to radiation attenuation
• Stereotactic surgery
• low geometric distortion
• Angiography

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Anatomical- CT
Radiotherapy planning
Real Time Multi-Trial Window
http//www.adaclabs.com/prodSolu/rtp/3dtp/3dtp.sht
ml
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Anatomical- CT
Radiotherapy planning
Dose distribution along path
shown as histogram colored according to the
volumes of interest.
http//www.uke.uni-hamburg.de/institute/imdm/idv/p
ublikationen/car1993/
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Anatomical- CT

• Intracranial bleeds
• Radiotherapy planning
• low geometric distortion
• CT contrast relates to radiation attenuation
• Stereotactic surgery
• low geometric distortion
• Angiography

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Anatomical- CT
MRI
CT
Brain with a deep central tumour
CT generally has better geometric
accuracy Patient a metal sterotactic frame, (
'spots' around the head in the images).
Streaking artifacts on the CT scans, because of
beam-hardening effects.
Dr Paul Morgan, from Academic Radiology
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Anatomical- CT

• Intracranial bleeds
• Radiotherapy planning
• low geometric distortion
• CT contrast relates to radiation attenuation
• Stereotactic surgery
• low geometric distortion
• Angiography

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Anatomical- CT
Angiography
Left carotid artery showing aneurysm
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Anatomical- CT
Angiography
Ascending aortic aneurysm
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Anatomical MRI

• Head (grey/white matter contrast)
• Tumours
• Multiple sclerosis
• Myelination in childhood
• Orthopaedic (no bone artefacts)
• Spine (sagittal views)
• Great vessels (no contrast agent)
• Bone and soft tissue tumours and disease
• Fluroscopy and Microscopy

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Anatomical MRI
Fetal imaging- brain
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Anatomical MRI
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Anatomical MRI

• Head (grey/white matter contrast)
• Tumours
• Multiple sclerosis
• Myelination in childhood
• Orthopaedic (no bone artefacts)
• Spine (sagittal views)
• Great vessels (no contrast agent)
• Bone and soft tissue tumours and disease
• Fluroscopy and Microscopy

MRI gives flexible contrast
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Anatomical MRI

• Head (grey/white matter contrast)
• Tumours
• Multiple sclerosis
• Myelination in childhood
• Orthopaedic (no bone artefacts)
• Spine (sagittal views)
• Great vessels (no contrast agent)
• Bone and soft tissue tumours and disease
• Fluroscopy and Microscopy

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Anatomical MRI
Orthopaedic MRI (sports injury)
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Anatomical MRI

• Head (grey/white matter contrast)
• Tumours
• Multiple sclerosis
• Myelination in childhood
• Orthopaedic (no bone artefacts)
• Spine (sagittal views)
• Great vessels (no contrast agent)
• Bone and soft tissue tumours and disease
• Fluroscopy and Microscopy

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MR Functional imaging Angiography
Pulmonary arteries
http//www.cardiac-mri.com
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Anatomical MRI

• Head (grey/white matter contrast)
• Tumours
• Multiple sclerosis
• Myelination in childhood
• Orthopaedic (no bone artefacts)
• Spine (sagittal views)
• Great vessels (no contrast agent)
• Bone and soft tissue tumours and disease
• Fluroscopy and Microscopy

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Anatomical MRI

• Head (grey/white matter contrast)
• Tumours
• Multiple sclerosis
• Myelination in childhood
• Orthopaedic (no bone artefacts)
• Spine (sagittal views)
• Great vessels (no contrast agent)
• Bone and soft tissue tumours and disease
• Fluroscopy and Microscopy

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Functional MRI
Cardiac MRI End diastole
http//www.cardiac-mri.com
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MR Functional imaging Fluroscopy
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MRI microscopy
Excised samples (in vitro)
Materials
Plants (in vivo)
Pharmaceutical Dosage Form
Castor Bean Seedling
Aplysia Neuron
Professor Bowtell
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Anatomical MRI and CT

• Abdominal cancer
• rectal
• prostate
• cervical, uterine
• bladder
• breast
• Brain cancer (meninges)
• Congential heart disease
• Dementia

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CT Functional Imaging

• CT is not a very functional modality
• However with contrast agents it can measure
• perfusion
• angiography
• renography
• But- this all requires dynamic repeated scanning
  dose is a problem

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MRI is a Functional Imaging Technique

• Perfusion
• Tracers
• Blood brain barrier permeability
• Lung function
• Molecular imaging?
• Physical properties of tissues
• microstructure from relaxation times
• microstructure from diffusion
• elastic properties
• fMRI- brain activation

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MRI is a Functional Imaging Technique

• Perfusion
• Tracers
• Blood brain barrier permeability
• Lung function
• Molecular imaging?
• Physical properties of tissues
• microstructure from relaxation times
• microstructure from diffusion
• elastic properties
• fMRI- brain activation

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MR Functional imaging- Perfusion
gt1000 500-1000 300-500 lt100
Perfusion rate ml/100g/min
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MR Functional imaging Blood brain barrier
permeability
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MRI is a Functional Imaging Technique

• Perfusion
• Tracers
• Blood brain barrier permeability
• Lung function
• Molecular imaging?
• Physical properties of tissues
• microstructure from relaxation times
• microstructure from diffusion
• elastic properties
• fMRI- brain activation

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MR Functional imaging Tracers
Lung ventilation using hyperpolarized helium
Dr Owers-Bradley
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MRI is a Functional Imaging Technique

• Perfusion
• Tracers
• Blood brain barrier permeability
• Lung function
• Molecular imaging?
• Physical properties of tissues
• microstructure from relaxation times
  microstructure from diffusion
• elastic properties
• fMRI- brain activation

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MRI is a Functional Imaging Technique

• Perfusion
• Tracers
• Blood brain barrier permeability
• Lung function
• Molecular imaging?
• Physical properties of tissues
• microstructure from relaxation times
• microstructure from diffusion
• elastic properties
• fMRI- brain activation

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MR Functional imaging Physical properties T1, T2
Measuring dilution in the stomach
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MRI is a Functional Imaging Technique

• Perfusion
• Tracers
• Blood brain barrier permeability
• Lung function
• Molecular imaging?
• Physical properties of tissues
• microstructure from relaxation times
• microstructure from diffusion
• elastic properties
• fMRI- brain activation

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MR Functional imaging Diffusion

• Staging stroke
• White matter tracts (diffusion anisotropy)

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MRI is a Functional Imaging Technique

• Perfusion
• Tracers
• Blood brain barrier permeability
• Lung function
• Molecular imaging?
• Physical properties of tissues
• microstructure from relaxation times
• microstructure from diffusion
• elastic properties
• fMRI- brain activation

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MRI is a Functional Imaging Technique

• Perfusion
• Tracers
• Blood brain barrier permeability
• Lung function
• Molecular imaging?
• Physical properties of tissues
• microstructure from relaxation times
• microstructure from diffusion
• elastic properties
• fMRI- brain activation

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MR Functional imaging fMRI
Which part of your brain senses touch?
Dr Francis
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MR Functional imaging fMRI
Fetuses can think too!
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An MRI study day