Blooming artifact (MRI)

Blooming artifact is a susceptibility artifact encountered on some MRI sequences in the presence of paramagnetic substances that affect the local magnetic milieux. Although it is an artifact, it may be deliberately exploited to improve detection of certain small lesions, much as the T1 shortening effects of low concentration gadolinium are used to detect contrast enhancement.

One of the most powerful and widely available sequences which maximizes blooming artifact to great effect is susceptibility-weighted imaging (SWI). Gradient echo and low B-value diffusion weighted imaging may also be useful in the absence of a dedicated susceptibility weighted sequence.

Blooming is seen surrounding a number of compounds:

• hemosiderin from prior hemorrhage, e.g. 
  • cavernous malformations
  • old intracerebral hemorrhage
  • diffuse axonal injury 
  • superficial siderosis
• calcification, particularly dystrophic, e.g.
  • neurocysticercosis (granulomatous stage)
• metal e.g. 
  • surgical or traumatic fragments
• gas e.g 
  • air embolism

History and etymology

The term 'blooming' refers to the fact that lesions appear larger than they actually are.