🧲 GRE-T2* Imaging [Neurosurgery Wiki]

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====== 🧲 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.