The physical properties of susceptibility weighted imaging and quantitative susceptibility mapping are connected with concrete clinical applications in neuroradiology. Future possible applications in muscoloskeletal imaging and lung imaging are demonstrated.
Synopsis
Susceptibility weighted imaging is a robust and fast MR- technology that is going to be transferred from neuroradiology into application for other organs. This work motivates clinical applications and shows the scientific and clinical significance of this sensitive imaging method.Background
Susceptibility weighted imaging uses the intrinsic magnetic properties of the examined tissue. This contrast differs from proton density-, T1- or T2-weighted MR images, since it represents the influence of neighboring substances with different susceptibilities on the phase of the measured signal. Susceptibility differences lead to phase differences that can be represented by phase images [1]. Phase images were postprocessed to amplify the contrast between different tissues [2]. That way distinct contrasts for objects with susceptibility difference to the surrounding tissue occur. Typical examples are: venous blood vessels [3], deposits of ferrous materials (iron oxide, blood metabolites) [4], susceptibility difference between air-tissue surfaces in lung imaging [5], calcification and fat deposit in tissue [6,7], contrast differences between white and gray matter [8]. Thus, susceptibility weighted imaging offers a huge number of possible applications in clinical diagnostics. The significance and relevance of cerebral disease pattern has been analyzed in a numerous of studies, e.g. [9] and [10]. Today susceptibility weighted imaging is an inherent part of cerebral MR-imaging and is progressively applied in other organs. Moreover, new developments like quantitative susceptibility mapping and susceptibility tensor imaging allow further application of susceptibility weighted imaging.Clinical applications
Susceptibility weighted imaging is applied for several reasons in diagnostics of stroke:
Outlook
Based on susceptibility weighted imaging sequences new imaging procedures have been developed in the last couple of years, especially quantitative susceptibility mapping and susceptibility tensor imaging. Quantitative susceptibility mapping allows to display the difference between calcareous materials and hemosiderin depositions. The efficiency of quantitative susceptibility mapping could be shown in glioblastoma to differentiate between blood residues and calcification. Further typical areas of application are neurodegenerative diseases, hematoma volume measurement, multiple sclerosis and the representation of kidney inflammation.