Pictorial Review

Insights into Imaging

, Volume 2, Issue 3, pp 335-347

Open Access This content is freely available online to anyone, anywhere at any time.

New MR sequences in daily practice: susceptibility weighted imaging. A pictorial essay

  • Roberto GasparottiAffiliated withNeuroradiology Unit, Department of Diagnostic Imaging, University of BresciaU. O. Neuroradiologia, Dipartimento di Diagnostica per Immagini, Università degli Studi di Brescia Email author 
  • , Lorenzo PinelliAffiliated withNeuroradiology Unit, Department of Diagnostic Imaging, University of Brescia
  • , Roberto LiserreAffiliated withNeuroradiology Unit, Department of Diagnostic Imaging, University of Brescia



Susceptibility-weighted imaging (SWI) is a relatively new magnetic resonance (MR) technique that exploits the magnetic susceptibility differences of various tissues, such as blood, iron and calcification, as a new source of contrast enhancement. This pictorial review is aimed at illustrating and discussing its main clinical applications.


SWI is based on high-resolution, three-dimensional (3D), fully velocity-compensated gradient-echo sequences using both magnitude and phase images. A phase mask obtained from the MR phase images is multiplied with magnitude images in order to increase the visualisation of the smaller veins and other sources of susceptibility effects, which are displayed at best after post-processing of the 3D dataset with the minimal intensity projection (minIP) algorithm.


SWI is very useful in detecting cerebral microbleeds in ageing and occult low-flow vascular malformations, in characterising brain tumours and degenerative diseases of the brain, and in recognizing calcifications in various pathological conditions. The phase images are especially useful in differentiating between paramagnetic susceptibility effects of blood and diamagnetic effects of calcium. SWI can also be used to evaluate changes in iron content in different neurodegenerative disorders.


SWI is useful in differentiating and characterising diverse brain disorders.


Brain Magnetic resonance imaging Susceptibility weighted imaging