Essentials of Functional MRI

Abstract

Introduction Basic Concepts Basic Anatomy of an MRI System Representing Images with Numbers and Vice Versa Recurring Math Concepts: Representing Data as Sums of Meaningful Components Source of the MR Signal and Its Properties Origins of the MR Signal. The Equilibrium State-Magnetization in Tissues Behavior of the Magnetization When Not at Equilibrium. Pushing the Magnetization Away from Equilibrium-The RF Pulse Detecting the MR Signal. Relaxation Back to Equilibrium Observing the Effects of Relaxation The Fundamental Building Blocks of MRI Methods: Spin Echoes and Gradient Echoes The Need for Echoes Spin Echo Gradient Echo. Steady-State Methods and Stimulated Echoes. Steady-State Methods Stimulated Echoes. Signal Weighting and Contrast Inversion-Recovery Methods Magnetization Transfer Contrast Summary Creating an Image from the Magnetic Resonance Signal Spatially Selective Radio-Frequency Pulses Encoding Spatial Information into the MR Signal to Create an Image Constructing an Image from k-Space Signal Strength, Imaging Speed, and Spatial Resolution-You Cannot Have It All Fast Imaging Methods Parallel Imaging Causes of Image Artifacts and Distortion Principles and Practice of Functional MRI How MRI Becomes Functional MRI Contrast Mechanisms: Linking the MR Signal and Neural Function General BOLD fMRI Methods Special Regions. Specific Examples of fMRI Applications-Setting the Acquisition Parameters Alternative Contrast Mechanisms Functional MRI Study Design Basic Principles of fMRI Study Design Choice of Stimulation Method or Task Choice of the fMRI Study Design Order and Timing of Presentation of Tasks or Stimuli Timing of Tasks or Stimuli, Duration, Sampling Rate. Summary of Factors Influencing fMRI Study Design Functional MRI Data Analysis Hypothesis Testing fMRI Analysis Software. Preprocessing Data Analysis Methods Statistical Threshold, and Correction for Multiple Comparisons Group Analysis Interpretation of fMRI Results-What Do They Really Mean? Clinical Applications of Functional MRI Examples of Current Clinical Applications of fMRI. Examples of Forthcoming Clinical Applications