Background: Susceptibility-weighted imaging (SWI), initially developed to provide an improved method for cerebral magnetic resonance (MR) venography, is now an integral part of neuroradiological diagnostics and is steadily gaining importance in non-cerebral imaging.
Principles: Tissue-inherent susceptibility differences generate a local magnetic field in which the dephasing of signal-producing protons occurs. This leads to a characteristic phase shift that can be used as a means to enhance contrast in the well-known T2*-weighted imaging.
Application in clinical routine: Many medically relevant pathologies induce tissue alterations that also influence the magnetic properties of tissue. Thus, the detection of blood residues and calcifications in SWI is superior to conventional MR sequences.
Future prospects: New techniques, such as quantitative susceptibility mapping (QSM) and susceptibility tensor imaging (STI) allow improved differentiation between blood residues and calcifications and provide an alternative imaging method for fiber tractography with respect to diffusion tensor imaging.
Keywords: Calcification; Hemorrhage; Magnetic susceptibility; Phase imaging; Susceptibility-weighted imaging (SWI).