Susceptibility weighted imaging (SWI) is highly sensitive to microhemorrhages because it exploits the pronounced magnetic susceptibility of blood breakdown products, specifically deoxyhemoglobin and hemosiderin. These substances create subtle variations in local magnetic fields, which we detect using advanced T2*-weighted gradient-echo sequences.
Unlike conventional MRI, we use a multi-step process to enhance these findings:
- Phase and Magnitude Data: We combine both types of imaging data to create high-contrast visuals, making even tiny petechial bleeds—some as small as 1–2 mm—highly visible.
- Signal Loss Visualization: The magnetic perturbations caused by blood products create phase shifts that translate into signal loss, allowing us to see microbleeds that appear as dark spots (hypointensities).
- Post-Processing: We apply techniques like minimum intensity projection (mIP) to suppress background signals and amplify the visibility of small veins and hemorrhages.
In the context of traumatic brain injury (TBI), this sensitivity is critical because SWI is 2–4 times more sensitive than standard gradient-recalled echo (GRE) sequences. It allows us to identify diffuse axonal injury (DAI) and chronic microhemorrhages that standard T2-weighted or FLAIR sequences often miss, providing objective evidence of trauma even weeks or months after an injury.
Results may vary based on individual patient conditions. Please consult with a healthcare professional for diagnosis and treatment advice.
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