Susceptibility-weighted Imaging: Technical Essentials and Clinical Neurologic Applications

Area of Science:

• Radiology
• Neuroimaging
• Magnetic Resonance Imaging

Background:

• Susceptibility-weighted imaging (SWI) has evolved from 2D T2*-weighted sequences to advanced 3D techniques.
• SWI is sensitive to magnetic field distortions caused by substances like calcium and iron, utilizing phase information for differentiation.
• The term SWI is often used broadly for susceptibility-enhanced sequences, regardless of phase data usage.

Purpose of the Study:

• To review the evolution and applications of SWI in neuroimaging.
• To highlight SWI's capability in detecting findings not visible on standard T2*-weighted images.
• To discuss the impact of acquisition techniques on SWI appearance.

Main Methods:

• Review of SWI and related sequence applications in neuroimaging.
• Comparison of SWI findings with standard T2*-weighted imaging.
• Analysis of SWI's utility in various neurological conditions.

Main Results:

• SWI improves depiction of known findings like microbleeds, superficial siderosis, and iron deposition.
• SWI identifies novel findings such as the nigrosome 1 in Parkinson disease, central vein sign in multiple sclerosis, and intratumoral susceptibility signals.
• Imaging appearance is highly dependent on acquisition techniques.

Conclusions:

• SWI is a valuable tool for enhanced neurovisualization, offering superior contrast for susceptibility-based findings.
• Its application extends beyond conventional uses, aiding in the diagnosis of subtle pathologies in neurodegenerative diseases, stroke, and neoplasms.
• Understanding acquisition techniques is crucial for interpreting SWI findings accurately.