Magnetic Resonance Imaging

FRCR Physics LecturesAnna Beaumont

anna.beaumont@hey.nhs.uk

(Acknowledgments: Dr Gary Liney)

In The Beginning….

Sagittal image of the human head (from Alfidi et al. 1982)

“..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

…‘Nuclear’ dropped and becomes MRI

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...

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

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 lecturesDate Covered 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