Phase imaging: Susceptibility-Weighted Imaging and Quantitative Susceptibility Mapping

The phase of the gradient echo MRI signal provides a rich source of information about tissue composition and integrity, which lends itself to various clinical and research applications. This chapter introduces acquisition methods and discusses the exceptional benefit of ultra-high field strength for gradient echo phase imaging. After introducing technical and biophysical sources of phase contrast, we focus on the two most widely used postprocessing methods for extracting physiologically relevant information from raw phase measurements: Susceptibility-Weighted Imaging (SWI) and Quantitative Susceptibility Mapping (QSM). This chapter outlines the processing steps in SWI and QSM and concludes with an overview of clinical applications made possible by phase imaging at ultra-high field.