🧲 GRE-T2* Imaging
GRE-T2\* (Gradient-Recalled Echo T2-star) is a magnetic resonance imaging (MRI) sequence that is highly sensitive to magnetic field inhomogeneities, making it especially useful for detecting substances like blood products, iron, or calcium in the brain.
🧠 Key Characteristics
- Uses gradient echo rather than spin echo, making it faster but more susceptible to artifacts.
- Sensitive to susceptibility effects, such as those caused by hemosiderin, microbleeds, or calcifications.
- Called T2\* because it reflects both T2 decay and local magnetic field variations.
- Often used to detect:
- Cerebral microbleeds
- Cavernous malformations (CCM)
- Calcifications
- Old hemorrhages
📈 Technical Notes
- Typically acquired in 2D or 3D format.
- Produces “blooming effect” where small areas of blood or metal appear larger.
- Less sensitive than SWI (Susceptibility Weighted Imaging) for small venous structures or subtle findings.
📌 Comparison
| Sequence | Sensitivity to blood | Sensitivity to small veins | Spatial resolution |
| ———— | ———————- | —————————– | ——————— |
| GRE-T2* | Moderate | Low | Moderate |
| SWI | High | High | High |
| CE-T1 | Low (but shows vessels with contrast) | Moderate | High |
✅ Best Practice
- Use GRE-T2* when time or access to advanced MRI sequences is limited.
- Prefer SWI or CE-T1 for detailed evaluation of developmental venous anomalies (DVAs) or subtle microvasculature.