Applications of Magnetic Resonance Imaging (MRI) and Computed Tomography CT) Lecture 1 F33AB5

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 ny.com/scannersound.h tml

Overview Advantages and problems of each technique Anatomical imaging Functional imaging Phillips

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

Advantages of CT (Limited) soft tissue contrast Spatial measurements exact (if set up correctly)

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)

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

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

Anatomical- CT Intracranial bleeds Radiotherapy planning –low geometric distortion –CT contrast relates to radiation attenuation Stereotactic surgery –low geometric distortion Angiography Chronic subdural haematoma

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

Real Time Multi-Trial Window Anatomical- CT Radiotherapy planning

Anatomical- CT Dose distribution along path shown as histogram colored according to the volumes of interest. Radiotherapy planning

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

Anatomical- CT MRICT 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. Brain with a deep central tumour Dr Paul Morgan, from Academic Radiology

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

Anatomical- CT Left carotid artery showing aneurysm Angiography

Anatomical- CT Ascending aortic aneurysm Angiography

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

Fetal Brain Placenta Fetal Lung Fetal Liver Anatomical MRI Fetal imaging- brain

LR Liver Spleen Kidneys Meal in fundus Meal in antrum Spinal cord 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

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

Anatomical MRI Orthopaedic MRI (sports injury)

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

MR Functional imaging Angiography Pulmonary arteries

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

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

Functional MRI Cardiac MRI End diastole

MR Functional imaging Fluroscopy

MRI microscopy Pharmaceutical Dosage Form Castor Bean Seedling Aplysia Neuron Materials Plants (in vivo) Excised samples (in vitro) Professor Bowtell

Anatomical MRI and CT Abdominal cancer –rectal –prostate –cervical, uterine –bladder –breast Brain cancer (meninges) Congential heart disease Dementia

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

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

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

Perfusion rate ml/100g/min > <100 MR Functional imaging- Perfusion

MR Functional imaging Blood brain barrier permeability

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

Lung ventilation using hyperpolarized helium MR Functional imaging Tracers Dr Owers-Bradley

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

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

liquid viscous 36 min48 min72 min Spleen Spinal cord LR Liver Meal Anatomical reference MR Functional imaging Physical properties: T1, T2 Measuring dilution in the stomach

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

MR Functional imaging Diffusion Staging stroke White matter tracts (diffusion anisotropy) lesion

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

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

Unit 5 Unit 1 Both digits Unit 7 Unit 8 Both units MR Functional imaging fMRI Which part of your brain senses touch? Dr Francis

Fetuses can think too! MR Functional imaging fMRI

An MRI study day