susceptibility-weighted imaging
MRI sequence that enhances contrast between tissues with different magnetic susceptibilities, particularly sensitive to venous blood and iron deposits.
Full Definition
Susceptibility-weighted imaging (SWI) is a specialized MRI technique that exploits differences in magnetic susceptibility between tissues to create high-resolution images. The sequence is exquisitely sensitive to deoxygenated blood in veins, iron deposits, calcium, and hemorrhage. SWI uses a long echo time gradient-echo sequence with phase information to enhance contrast. It has revolutionized the detection of microbleeds, developmental venous anomalies, and traumatic brain injury. The technique is particularly valuable in stroke imaging, where it can detect hemorrhagic transformation not visible on conventional sequences.
Usage
Usage note: Hyphenate when used as an adjective; commonly abbreviated as SWI in clinical practice.
In Context
- "Susceptibility-weighted imaging demonstrated multiple microhemorrhages consistent with diffuse axonal injury." — Emergency radiology report
- "The imaging protocol was modified to include susceptibility-weighted imaging for better detection of cerebral microbleeds." — Clinical protocol revision