Susceptibility-weighted imaging for differential diagnosis of cerebral vascular pathology: A pictorial review

Susceptibility-weighted imaging (SWI) is a high-spatial resolution, three-dimensional, gradient-echo (GRE) magnetic resonance (MR) technique. This fully velocity-compensated pulse sequence utilizes the magnetic susceptibility differences of various tissues or substances, such as blood products, iron, and calcification. By postprocessing the magnitude images using a phase mask, it emphasizes the magnetic properties of different susceptibility effects. Generated minimal intensity projection (minIP) images can further demonstrate tortuous vasculature and the continuity of vessels or abnormalities across slices. SWI has been used to improve the diagnosis of neurological trauma, brain neoplasm, neurodegenerative disorders, and cerebrovascular disease because of its ability to demonstrate microbleeds and conspicuity of the veins and other sources with susceptibility effects. We have used SWI to identify cerebrovascular lesions which may be obscured on other MR sequences to aid in the differential diagnosis. We present a review with selected cases to demonstrate the usefulness of this new neuroimaging technique in improving the diagnosis of cerebral vascular pathology.