Magnetic Resonance Imaging FRCR Physics Lectures Anna Beaumont anna.beaumont@hey.nhs.uk (Acknowledgments: Dr Gary Liney)

In The Beginning…. Sagittal image of the human head (from Alfidi et al. 1982) …‘Nuclear’ dropped and becomes MRI Within 5 years clinical standard images although still only University research. Industry begins to get involved and MRI takes off. “..we feel sure that in the very near future commercial machines capable of producing medical images for hospital use will be available.” P.Mansfield and P.G. Morris 1982

MRI Today MRI is the imaging modality of choice in the brain and spinal cord Soft-tissue contrast with large degree of manipulation, non-ionising radiation, multi-planar in any orientation. Many more areas of use (eg breast, cardiac, whole-body scans). Advanced techniques currently being developed for clinical practice... Many advantages, biggest disadvantgae is cost. This talk will concentrate on some of the newest areas in an ever increasing field

FRCR MRI Syllabus 4.16 Nuclear Magnetic Resonance Nuclear spin angular momentum and nuclear magnetic moment Bulk magnetisation and the effect of magnetic field strength Precession in a magnetic field and the Larmor equation Resonance with radiofrequency pulses Relaxation mechanisms and relaxation times Free induction decay signal

FRCR MRI Syllabus 4.17 Magnetic Resonance Imaging Construction, function and operation of a superconducting MRI scanner Permanent and resistive magnets Radiofrequency receiver coils Spin-echo pulse sequence Spatial localisation of the signal K-space, image acquisition and image reconstruction Multi-echo, fast spin-echo and single shot techniques Gradient echo imaging- basic spoiled and non-spoiled techniques

FRCR MRI Syllabus 4.17 Magnetic Resonance Imaging (cont) Tissue suppression methods- short TI inversion recovery (STIR), fluid attenuated inversion recovery (FLAIR) and fat saturation Standard gadolinium extracellular space contrast agents Other MR contrast agents Magnetic resonance angiography Basic principles of diffusion techniques and diffusion weighted imaging Dynamic contrast enhancement and perfusion imaging

FRCR MRI Syllabus 4.17 Magnetic Resonance Imaging (cont) Principles of magnetic resonance spectroscopy (MRS) Spatial misregistration, chemical shift, susceptibility, motion, flow and other artefacts Cell biology principles underpinning dynamic contrast enhanced and diffusion weighted MRI

FRCR MRI Syllabus 4.18 Safety in Magnetic Resonance Imaging Static magnetic field- projectiles, induced voltage, implants Fringe field and controlled area Time-varying gradient fields- eddy currents, stimulation, implanted devices, acoustic noise Radiofrequency fields- specific absorption rate, heating Safety of patients, staff and members of the public Pregnant patients Shielding and imaging room design Safety guidelines for Magnetic Resonance Imaging equipment in clinical use

Further Reading…

Resources Blink Penelope Allisy Roberts, Jerry Williams Hashemi, Bradley, Lisanti Westbrook McRobbie, Moore, Graves, Prince Blink

Resources: Online www.onlinemri.co.uk http://mri-q.com RITI system www.e-lfh.org.uk/programmes/radiology www.imaios.com/en/e-Courses/e-MRI

Programme of these lectures Date Covered 6/10/15 1: Basic Physics 17/11/15 6: Basic Pulse Sequences 13/10/15 2: Spatial Encoding 26/11/15 7: More Complex Techniques – Part I 20/10/15 3: Equipment & Safety 3/12/15 8: More Complex Techniques – Part II (incl. case studies presented by Dr David Salvage, Consultant Radiologist) 29/10/15 4: Scanner session 8/12/15 9: Artefacts 10/11/15 5: K Space & Imaging Parameters 10/12/15 10: Revision Questions