RadteraMRA Head (Intracranial) Without Contrast
MRNo contrastNeuro
Indications
- Suspected intracranial aneurysm
- Aneurysm screening (family history, ADPKD)
- Intracranial stenosis
- AVM / vascular malformation
- Vasculitis / vasospasm follow-up
Patient prep
- MRI safety screening
- No fasting; no IV needed for standard TOF
- Head coil
Contrast
None / non-contrast
Technique
- 3D time-of-flight (TOF) is the standard non-contrast technique for circle of Willis
- Axial 3D TOF slab covering skull base through above the circle of Willis
- Use multiple overlapping thin slabs (MOTSA) and ramped RF to limit saturation
- Superior saturation band to suppress venous flow; MIP reconstructions in multiple projections
Series / Sequences
| # | Series / Sequence | Plane | Weighting / Recon | Thickness | Notes |
|---|---|---|---|---|---|
| 1 | 3D TOF MRA | axial (source) | TOF GRE | 0.6-1 mm | Circle of Willis; thin source images + MIPs |
| 2 | MIP reconstructions | multiple | TOF MIP | N/A | Rotational MIPs for aneurysm display |
Key points
- Always review source images, not only MIPs—small aneurysms and stenoses are missed on MIP alone.
- TOF overestimates stenosis severity due to turbulent flow signal loss.
- For AVM/fistula or when TOF inadequate, add contrast-enhanced or time-resolved MRA (e.g., TWIST/TRICKS).
- Often paired with MRA neck for full vascular survey.
References
• ACR-ASNR-SPR Practice Parameter for Performing and Interpreting MR Angiography
• Radiopaedia: Intracranial MRA link
• ACR Appropriateness Criteria: Cerebrovascular Disease
• Radiopaedia: Intracranial MRA link
• ACR Appropriateness Criteria: Cerebrovascular Disease
Source: Researched — verify against your institution
Reference template — verify and adapt to your scanner, vendor and institution before clinical use. Not a substitute for clinical judgment.