Instituto Politécnico de Coimbra Escola Superior de Tecnologia da Saúde Coimbra MRI (1.5 and 3 Tesla) sequence optimization for use in Orthopaedics Cláudio Pereira Mestrado em Ciências Nucleares Aplicadas na Saúde 2016 Instituto Politécnico de Coimbra Escola Superior de Tecnologia da Saúde Coimbra Mestrado em Ciências Nucleares Aplicadas na Saúde Dissertação MRI (1.5 and 3 Tesla) sequence optimization for use in Orthopaedics Cláudio Pereira Orientador: Professor Doutor Francisco Alves Coimbra, Dezembro, 2016 Information about the Author: Cláudio Leonel Duarte Pereira Bachelor of Radiography at Aveiro University, Portugal Master´s Student in Nuclear Sciences Applied in Health at College of Health Technologies of Coimbra, Portugal Senior MRI Radiographer at Nuffield Orthopaedic Centre, Oxford University Hospital NHS Trust, UK Contact: 1. [email protected] 2. [email protected] 3. +44 (0)7925366332 Author’s note: Dedicated to whoever reads more than 50% of this work. I would happily read 5 pages of this work for every page that I didn’t had to write. Master in Nuclear Sciences Applied in Health December 2016 Associated Published Scientific Works Published Presentations & Posters related to the following dissertation 1. Pereira C, Partington K. “Reducing metal artefacts in MRI: a retrospective analysis of improved diagnostic quality and reporting confidence without the use of specialized commercial pulses/techniques”. Ed: ECR of. In. Vienna, Austria: European Society of Radiology; 2016. 2. Pereira C, Partington K. “Fast scans and better images at Zero cost in Clinical MRI”. Ed: ESMRMB Congress. In. Edinburgh, Scotland: European Society of Magnetic Resonance in Medicine and Biology; 2015. Cláudio Leonel Duarte Pereira iii Master in Nuclear Sciences Applied in Health December 2016 Index Index PUBLISHED PRESENTATIONS & POSTERS RELATED TO THE FOLLOWING DISSERTATION .......................................... III SCIENTIFIC ABSTRACT ......................................................................................................................... VIII RESUMO (PORTUGUESE VERSION OF SCIENTIFIC ABSTRACT) .......................................................................... IX ABBREVIATIONS ................................................................................................................................... X SECTION 1: EDUCATIONAL BACKGROUND ................................................................... 1 DISSERTATION SYNOPSIS ........................................................................................................................ 1 SINOPSE DE DISSERTAÇÃO (PORTUGUESE VERSION OF THE SYNOPSIS) ............................................................... 3 INTRODUCTORY NOTE ............................................................................................................................ 4 1 OBJECTIVES ............................................................................................................................ 5 2 DISSERTATION ADVISORS........................................................................................................... 5 3 LOCATION .............................................................................................................................. 5 4 AUTHORIZATIONS .................................................................................................................... 5 SECTION 2: CONTEXTUALIZATION .................................................................................. 6 5 CONTEXTUALIZATION OF MRI IN TODAY’S CLINICAL SETTING ............................................................. 6 5.1 The interest and advantages of sequence optimization ...................................................................... 6 6 MRI’S PHYSICAL PRINCIPLES ...................................................................................................... 7 6.1 Nucleons, Spin and Stable Energy States ............................................................................................. 7 6.2 Resonance Principles and Precession Frequency ................................................................................. 8 6.3 Relaxation: Recover, Decay and Dephasing ........................................................................................ 9 6.4 Why Hydrogen-based MRI ................................................................................................................. 11 6.5 Technical and Technological Principles.............................................................................................. 12 6.5.1 RF pulses .................................................................................................................................. 12 6.5.2 Signal acquisition, Gradients and image encoding ................................................................... 13 6.5.3 Why use Echoes instead of FID? .............................................................................................. 14 6.5.4 MRI coils. .................................................................................................................................. 15 6.5.5 Sampling signal and the Nyquist Theorem ............................................................................... 17 7 BASIC IMAGE WEIGHTS: T1, T2, PD AND T2* ............................................................................. 17 8 MRI SEQUENCES ................................................................................................................... 20 8.1 Types of sequences used in orthopaedic MRI. ................................................................................... 21 8.2 Spin Echo (SE) .................................................................................................................................... 22 8.2.1 Multi-echo Spin Echo ............................................................................................................... 23 8.2.2 Inversion Recovery (IR) ............................................................................................................ 24 8.2.3 RARE ......................................................................................................................................... 25 8.3 Gradient Echo (GE) ............................................................................................................................ 29 8.3.1 Multi-Echo Gradient Echo ........................................................................................................ 30 8.3.2 Spoiled Gradient Echo .............................................................................................................. 30 8.3.3 Steady State GE ........................................................................................................................ 31 8.3.4 Ultrafast Gradient Echo/Turbo Field Echo (TFE) ...................................................................... 32 Cláudio Leonel Duarte Pereira iv Master in Nuclear Sciences Applied in Health December 2016 Index 8.4 Hybrid Sequences .............................................................................................................................. 33 8.4.1 SE- EPI ...................................................................................................................................... 33 8.4.2 GRASE ....................................................................................................................................... 34 9 MRI PARAMETERS; ................................................................................................................ 35 9.1 Basic parameters; .............................................................................................................................. 35 9.1.1 Image Weight, TR, TE and Flip Angle ........................................................................................ 35 9.1.2 Phase encoding direction ......................................................................................................... 42 9.1.3 Slice Thickness and Slice Gap ................................................................................................... 43 9.1.4 Resolution: Field of View, Matrices and Pixels ......................................................................... 44 9.1.5 Oversampling/Fold-over suppression ...................................................................................... 46 9.1.6 Averages/NEX........................................................................................................................... 48 9.1.7 Saturation Bands ...................................................................................................................... 48 9.2 Advanced MRI parameters ................................................................................................................ 49 9.2.1 Turbo Factor ............................................................................................................................. 49 9.2.2 Echo Train ................................................................................................................................ 50 9.2.3 Echo Spacing ............................................................................................................................ 51 9.2.4 Concatenations/Packages ........................................................................................................ 51 9.2.5 Driven Equilibrium (DRIVE/RESTORE) .....................................................................................