Foot MRI protocol
A small, curved region where fat suppression fails easily and the targets (the plantar plate, a Morton's neuroma, a stress fracture) are millimetres across. The job is to plan to the metatarsal axis and keep the fat dark.
By the ScanFlo Editorial Team · Updated
In this section · Protocols
When this study is used
- Forefoot pain: plantar plate tear, Morton's neuroma or metatarsalgia.
- Stress fracture or osteomyelitis.
- Midfoot or Lisfranc injury; soft-tissue mass.
Patient & coil positioning
- Feet-first supine in a dedicated foot/ankle coil; forefoot centred and flat.
- Strap the foot; even toe motion blurs the fine structures.
- Small FOV and high matrix; the plantar plate and interdigital nerves are tiny.
Localizer
Three-plane localizer covering the target region (forefoot, midfoot or whole foot as indicated).
Sequence planning
For each sequence below you get the reference line the slice group follows, how much it covers, and why the sequence is in the protocol at all. Plan against the localizer, not by eye.
Short-axis (axial to metatarsals) PD/T2 fat-sat
Short-axisPlanning: Perpendicular to the metatarsal shafts through the region of interest.
Why: Plantar plate, interdigital (Morton's) neuromas and intermetatarsal bursae in cross-section.
Long-axis (sagittal to metatarsals) PD/T2 fat-sat
Long-axisPlanning: Parallel to the metatarsal shafts.
Why: Plantar-plate insertion, tendons and joint alignment along the ray.
Coronal (dorsoplantar) STIR
Coronal / dorsoplantarPlanning: Across the forefoot.
Why: Marrow oedema (stress fracture, osteomyelitis), with suppression that holds up over the curved foot.
T1
AnyPlanning: Matched coverage.
Why: Anatomy, marrow replacement and fracture lines.
Representative parameters
Treat these as ranges. Field strength, coil and vendor all move the numbers. What must not move is understanding why each sits where it does.
| Sequence | Matrix / FOV | Notes |
|---|---|---|
| Short-axis PD FS | 320–384 / 10–14 cm | Plantar plate, Morton's neuroma |
| Long-axis PD FS | 320 / 12–16 cm | Plate insertion, alignment |
| STIR | 256–320 / 12–16 cm | Marrow oedema; reliable suppression |
| T1 | 320 / 12–16 cm | Anatomy, fracture |
Artifacts & how to fix them
| Artifact | Typical cause | Mitigation |
|---|---|---|
| Fat-sat failure | Curved foot, air interface | Re-shim on the forefoot; STIR; Dixon |
| Low resolution | FOV too large for tiny targets | Small FOV, high matrix |
| Toe motion | Involuntary movement | Strap the foot; raise NEX |
| Magic angle | Curved tendon at 55° | Compare on T2 (long TE) |
What am I looking at?
You are not reporting the study, but recognising pathology helps you keep it in the field of view and know when to add a sequence or contrast. How the common findings read on the console:
| Finding | Sequence to check | How it reads |
|---|---|---|
| Plantar plate tear | Short + long-axis PD FS | Fluid/discontinuity at the plantar-plate insertion (usually 2nd MTP) |
| Morton's neuroma | Short-axis PD FS / T1 | Teardrop soft-tissue mass in the intermetatarsal space, dark on T2 |
| Stress fracture | STIR + T1 | Bright marrow oedema on STIR; a dark fracture line on T1 |
Review checklist
- Short-axis perpendicular to the metatarsals for the plantar plate and neuromas.
- Long-axis along the ray for the plate insertion.
- Fat suppression uniform (or STIR) over the curved forefoot.
- Small FOV and high matrix for the fine structures.
Mistakes that cost repeats
- Fat-sat failing over the curved foot and hiding oedema.
- FOV too large to resolve a small neuroma or plate tear.
- Toe motion blurring the study.
- Planes not referenced to the metatarsal axis.
Common questions
- How is a Morton's neuroma seen on MRI?
- As a teardrop-shaped soft-tissue mass in the intermetatarsal space (commonly the 2nd–3rd), typically low signal on T2 because it is fibrous. A short-axis fat-suppressed sequence perpendicular to the metatarsals shows it best, often with an adjacent intermetatarsal bursa.
- Why does foot MRI need STIR rather than spectral fat-sat?
- The foot is curved and sits away from the magnet isocentre, so the local field is inhomogeneous and frequency-based fat suppression fails patchily. STIR suppresses fat by inversion time, staying uniform across the forefoot.
- How are the imaging planes referenced in the foot?
- To the metatarsal shafts: a short-axis plane perpendicular to them for the plantar plate and interdigital nerves, and a long-axis plane parallel to them for the plate insertion and ray alignment.
Try it in ScanFlo: Plan a short-axis stack perpendicular to the metatarsals through the forefoot and look in the intermetatarsal spaces. That plane is what reveals a Morton's neuroma or a plantar-plate tear the routine views would miss. See ScanFlo MRI →