Multiphase CT angiography [Neurosurgery Wiki]

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====== Multiphase CT angiography ======

===== Indications =====

Multiphase [[CT angiography]] (MP-CTA) is an advanced [[imaging]] technique used primarily to assess vascular structures in various clinical settings, including stroke, trauma, and aneurysm evaluation. It involves obtaining multiple sets of CT images over different time phases after contrast injection to evaluate blood flow dynamics.

==== Phases ====

Typically, MP-CTA consists of:

1. **Early Arterial Phase** – Captures contrast as it enters the arterial system, providing high-resolution imaging of arteries.

2. **Peak Arterial Phase** – Offers optimal visualization of arterial anatomy, often used for aneurysm and stenosis evaluation.

3. **Late Arterial/Early Venous Phase** – Allows assessment of arteriovenous shunting, collateral circulation, and venous filling.

4. **Venous Phase** – Helps in evaluating venous anatomy and pathology.

5. **Delayed Phase** (optional) – Useful in detecting slow-flow lesions, venous malformations, or blood-brain barrier breakdown.

==== Clinical Applications ====


[[Multiphase CT angiography in acute ischemic stroke]].

- **Acute Ischemic Stroke:** Helps in assessing collateral circulation, which is crucial for deciding on endovascular treatment.

- **[[Intracranial Aneurysm Diagnosis]]:** Improves detection sensitivity compared to single-phase CTA.

- **Arteriovenous Malformations (AVMs):** Provides insight into arterial feeders, nidus, and venous drainage.

- **Trauma:** Identifies active bleeding sites and vascular injuries.

- **Peripheral Vascular Disease:** Assists in detecting arterial stenosis and occlusion.

- **Oncology:** Assesses tumor vascularity and response to anti-angiogenic therapies.

==== Advantages Over Conventional CTA ====

- Improved **visualization of collaterals** in stroke patients.

- Enhanced detection of **delayed-filling aneurysms** or vascular abnormalities.

- Reduced risk of **missing arterial pathology** due to timing discrepancies.

- **Dynamic blood flow assessment** without requiring invasive catheter-based angiography.

==== Technical Considerations ====

- Requires **synchronized contrast administration** and **precise timing** of scans.

- Higher **radiation dose** compared to single-phase CTA, though optimized protocols can mitigate this.

- Can be combined with **perfusion imaging** for comprehensive stroke assessment.

==== Conclusion ====

MP-CTA is a powerful tool in neurovascular and cardiovascular imaging, offering dynamic insights into blood flow and vascular integrity. Its applications continue to expand with advancements in CT technology and post-processing algorithms.