MRI Mid-Foot – Generic Standard Protocol

1. Executive Summary

Mid-foot MRI occupies a specific niche in musculoskeletal imaging: it is the modality of choice for soft tissue and bone marrow pathology that is invisible or equivocal on plain radiography and CT, yet it requires technical precision that is distinctly more demanding than most other foot and ankle MRI examinations. The mid-foot — comprising the navicular, cuboid, three cuneiform bones, and the bases of the five metatarsals — is a small, geometrically complex region where the diagnostic structures of interest (Lisfranc ligament complex, plantar fascia mid-foot attachments, peroneal and tibialis posterior tendon insertions, tarsometatarsal articular surfaces, cuboid and navicular cortex) are often 1–3 mm in dimension. This demands both optimal coil selection and careful slice-plane prescription relative to the individual foot anatomy.

The clinical context is broad: from diabetic foot with suspected Charcot neuroarthropathy — where MRI detects early osseous oedema before radiographic changes — to athletic Lisfranc injury, to stress fracture of the navicular or metatarsal bases, to inflammatory arthropathy of the tarsometatarsal joints. All of these require a dedicated approach that neither the ankle protocol nor a generic foot survey addresses optimally.

CT remains superior for cortical bone detail, fracture line delineation in acute trauma, and detection of small calcifications (plantar plate calcification, accessory ossicle characterisation). Radiography is the first-line modality for acute trauma. Ultrasound is the first-line modality for superficial soft tissue assessment (Morton's neuroma, plantar fascia thickness). MRI supersedes all these modalities for bone marrow assessment, early stress reaction, early Charcot change, cartilage, ligament (particularly Lisfranc), and deep soft tissue pathology.

1.1 Core Strengths

Bone marrow sensitivity: MRI detects bone marrow oedema from stress reaction, early stress fracture, early Charcot neuroarthropathy, and inflammatory arthropathy weeks before radiographic changes become visible. STIR and fat-suppressed PD sequences are the most sensitive bone marrow sequences available in any modality.

Lisfranc ligamentous assessment: the Lisfranc ligament complex — comprising the dorsal, interosseous, and plantar Lisfranc ligaments between the medial cuneiform and the second metatarsal base — is the primary stabiliser of the tarsometatarsal (TMT) joint and the structure whose integrity determines surgical versus conservative management. Coronal and axial sequences at high resolution reliably display the interosseous Lisfranc ligament (the most important component) and its dorsal counterpart.

Charcot neuroarthropathy staging: MRI differentiates active Charcot (bone marrow oedema, joint effusion, ligamentous disruption) from inactive/chronic Charcot (sclerosis, fragmentation, deformity), and distinguishes Charcot from osteomyelitis — a clinically critical and diagnostically challenging differentiation in the diabetic foot.

Tarsal coalition characterisation: fibrous and cartilaginous coalitions between the mid-foot tarsal bones (particularly calcaneonavicular) produce characteristic intermediate T1/T2 signal bridging, and the associated bone marrow changes are clearly depicted on MRI.

Plantar plate and plantar fascia: the plantar fascia at the mid-foot and the plantar plates of the tarsometatarsal joints are best assessed on sagittal and coronal MRI sequences.

1.2 Intrinsic Limitations of the Generic Protocol

Cortical detail is inferior to CT: stress fracture lines, subtle cortical disruption at the tarsometatarsal joints, and periosteal reaction are better seen on CT. For acute trauma where surgical planning requires precise cortical fracture anatomy, CT is the complementary tool.

Resolution at the detection limit for small ligaments: the Lisfranc interosseous ligament is 2–4 mm wide. At the resolution achievable with a standard hand/wrist phased-array coil (the typical coil for mid-foot MRI), this structure is at the detection threshold. Partial tears versus complete tears can be difficult to discriminate, particularly for the plantar Lisfranc ligament.

Dynamic and weight-bearing assessment not possible: weight-bearing MRI is not widely available. The clinical instability of a Lisfranc injury is best assessed on weight-bearing radiographs. MRI documents the ligamentous injury but cannot directly demonstrate the functional instability.

Neuroarthropathy vs osteomyelitis differentiation remains imperfect: despite multiple proposed MRI criteria, the differentiation of active Charcot neuroarthropathy from superimposed osteomyelitis remains one of the most challenging diagnostic problems in the diabetic foot. The generic protocol provides the sequences for this assessment but the differentiation requires clinical integration and is not resolved by MRI alone.

When dedicated child protocols are required: diabetic foot (Charcot vs osteomyelitis dedicated protocol); Lisfranc injury pre-surgical mapping; navicular stress fracture protocol; plantar plate injury; inflammatory arthropathy of the TMT joints; tarsal tunnel syndrome (more distal); Morton's neuroma (forefoot, not mid-foot).

2. Main Clinical Indications

2.1 Standard Indications

Lisfranc ligament injury is the primary sports medicine indication for mid-foot MRI. The Lisfranc injury spectrum ranges from ligamentous sprain to complete tarsometatarsal dislocation, and distinguishing partial from complete ligamentous disruption is the critical management decision. Weight-bearing radiographs should always precede MRI for acute Lisfranc trauma; MRI adds the ligamentous map and bone marrow injury pattern that radiographs cannot provide. The generic protocol with high-resolution coronal and axial PD-FS sequences centred on the tarsometatarsal joints is adequate for initial assessment.

Navicular stress fracture and stress reaction are among the most common mid-foot injuries in runners and military recruits. Plain radiographs and CT are relatively insensitive for early stress reaction; MRI demonstrates bone marrow oedema and early stress fracture lines weeks before radiographic changes. The navicular — at the apex of the medial longitudinal arch and subject to maximal compressive forces in the transverse plane — has a central avascular zone that makes navicular stress fractures prone to non-union. MRI characterises the fracture completeness and the avascular zone involvement, which guides surgical versus conservative management.

Charcot neuroarthropathy in the setting of diabetic peripheral neuropathy is one of the most clinically important mid-foot indications. The tarsometatarsal and Lisfranc joints are among the most common Charcot sites. Early active Charcot produces bone marrow oedema that may be indistinguishable clinically from deep infection, and the management is opposite (off-loading vs surgical debridement). MRI with contrast is the most sensitive imaging tool for staging Charcot activity and for raising the possibility of superimposed osteomyelitis.

Diabetic foot and suspected osteomyelitis at the mid-foot level — particularly overlying the cuboid, cuneiform bones, and metatarsal bases — requires MRI as the primary diagnostic tool when deep infection or osteomyelitis is suspected and plain radiographs are equivocal or negative. The generic protocol with STIR, T1, and post-contrast T1 covers the essential sequences; gadolinium is mandatory for this indication.

Accessory ossicle pathology — particularly os naviculare (os tibiale externum) and accessory cuneiform ossicles — produces mid-foot pain when the fibrocartilaginous synchondrosis between the accessory bone and the parent bone becomes symptomatic. MRI demonstrates the synchondrosis signal, associated bone marrow oedema, and the relationship to the tibialis posterior tendon insertion. The generic protocol is usually adequate.

Tarsal coalition involving calcaneonavicular and naviculocuneiform coalitions produces mid-foot pain and limited subtalar motion in adolescents and young adults. CT characterises the coalition type (bony vs fibrocartilaginous) better than MRI for bony coalitions; MRI demonstrates fibrocartilaginous coalitions and the associated bone marrow changes at the coalition margins better than CT.

Mid-foot arthritis and inflammatory arthropathy: tarsometatarsal joint osteoarthritis is common after mid-foot trauma and in older patients. MRI demonstrates cartilage loss, subchondral marrow changes, and synovitis — particularly relevant when distinguishing post-traumatic osteoarthritis from active inflammatory arthropathy (rheumatoid, psoriatic, gout).

2.2 Urgent Red Flags Requiring Expedited or Emergency Imaging

The mid-foot is not a life-threatening anatomical region. However, the following scenarios require prompt imaging:

3. Preparation Reference

Universal MRI safety screening is covered in the general MRI preparation page and is not repeated here.

3.1 Anatomy-Specific Preparation Items

Footwear and socks: the patient must remove all footwear, socks, compression stockings, and foot orthoses before the examination. Metallic components in athletic footwear (insoles with metallic stiffeners, ankle braces with metallic stays) produce susceptibility artefacts at the field of view margins. Compression stockings produce minor skin impressions that do not affect imaging but should be removed to allow accurate coil placement.

Prior surgical hardware: mid-foot surgery — Lisfranc fusion with screws and plates, navicular fixation, tarsometatarsal arthrodesis — produces metallic susceptibility artefacts that can significantly degrade imaging of the fused segments. At 3T, the blooming from stainless steel hardware is 4× larger than at 1.5T. For post-operative mid-foot MRI with hardware, 1.5T is strongly preferred and MARS (Metal Artefact Reduction Sequences) techniques should be applied. Titanium hardware produces substantially less artefact than stainless steel.

Diabetic patient preparation: for suspected Charcot or osteomyelitis, blood glucose should be measured before the examination. Extremely elevated glucose does not contraindicate MRI but must be documented as it may affect clinical decision-making based on the imaging findings.

Pain and immobility: mid-foot pain can make positioning uncomfortable, particularly in patients with Charcot deformity, post-surgical foot, or acute ligamentous injury. Mild analgesia 30–60 minutes before the examination improves positioning tolerance and reduces motion. A pillow or foam pad under the knee reduces the dorsiflexion at the ankle that otherwise causes involuntary foot motion during the examination.

Bilateral comparison: the contralateral foot is occasionally useful for comparison, particularly in children or young patients with suspected accessory ossicle variants, or in early Charcot where the "normal" side provides a reference. Bilateral comparison adds scan time but can be achieved in most patients by repositioning.

3.2 Patient Positioning on the MRI System

Position options: three positions are available for mid-foot MRI, each with specific advantages:

Superman/prone with foot extended overhead: the preferred position for mid-foot MRI when the patient tolerates it. Placing the mid-foot at or near isocentre maximises B0 homogeneity and SNR. Fat suppression quality is best at isocentre. The foot is dorsiflexed at approximately 20° (the "neutral" foot position), keeping the plantar surface roughly horizontal.

Supine feet-first: the foot is imaged in the bore with the patient supine and feet entering the bore first. The mid-foot will be approximately 30–40 cm from isocentre in a standard 60–70 cm bore scanner. This off-isocentre position degrades fat suppression with spectral methods (CHESS/SPAIR), making Dixon fat suppression mandatory in this position. Despite this limitation, feet-first supine is the most comfortable position for most patients.

Supine head-first (arm-at-side): the affected foot is placed in the scanner along with the patient's body. This positions the foot very far from isocentre (> 60 cm) and is the worst position for fat suppression. Only acceptable as a last resort when feet-first and Superman are not possible.

Coil selection: a dedicated small extremity coil (hand/wrist phased-array) or a dedicated foot/ankle coil, placed directly over the mid-foot, provides the highest SNR for mid-foot imaging. The hand/wrist coil (typically 8 channels, internal diameter 10–15 cm) is the most commonly available coil for mid-foot MRI in general radiology departments. A 16-channel small extremity coil provides superior SNR for very high-resolution work (sub-millimetre in-plane resolution) but is less commonly available. Avoid using a large body coil or knee coil for mid-foot — the coil-to-tissue distance is too large and SNR is insufficient for the required resolution.

Centring: isocentre at the level of the second TMT joint (the most constrained and clinically important TMT joint) — approximately at the proximal shaft of the second metatarsal. Verify on the three-plane localiser that all five TMT joints, the cuboid, the three cuneiforms, and the navicular are within the FOV. For a specific navicular stress fracture evaluation, centre at the navicular.

Foot alignment: place the foot in a neutral dorsiflexion position (approximately 0–20° plantar flexion from the knee axis). Avoid forced plantar flexion, which distorts the tarsometatarsal relationships. The plantar surface of the foot should be roughly perpendicular to the floor of the coil. Verify anatomical alignment on the three-plane localiser — the second metatarsal long axis should be approximately parallel to the superior-inferior direction in the scanner on the coronal view.

Immobilisation: foam wedges or rolled towels around the foot within the coil reduce inadvertent motion. For the Superman position, a strap or tape over the dorsum of the foot secured to the coil table prevents ankle extension during the examination.

Common positioning errors:

• Foot excessively plantar-flexed: the TMT joint plane is oblique rather than perpendicular to the axial plane, degrading the ability to assess TMT joint spacing
• Coil placed too proximally over the ankle: mid-foot is at the edge of the coil sensitivity region; SNR dramatically reduced
• Foot rotated within the coil (supinated or pronated): the coronal plane cuts through the cuneiforms asymmetrically, making symmetry comparison impossible

4. Standard Protocol Design

The mid-foot MRI protocol is built around three orthogonal planes — coronal, sagittal, and axial — each prescribed relative to the foot long axis, with PD fat-suppressed sequences as the primary diagnostic tool supplemented by T1 for anatomy and STIR for bone marrow screening.

4.1 Mandatory Core Sequences

4.2 Conditional Sequences

4.3 Rationale Summary Per Sequence

Coronal PD-FS is the primary sequence for the mid-foot and the plane in which the Lisfranc ligament complex is best visualised. The coronal plane of the foot — perpendicular to the long axis of the metatarsals — displays the tarsometatarsal joints in cross-section, showing the articular surfaces of all five TMT joints simultaneously, the cuneiform–metatarsal base relationships, and — critically — the interosseous Lisfranc ligament as a low-signal band running between the medial cuneiform and the second metatarsal base. This ligament is only 2–4 mm wide and requires ≤ 0.4 × 0.4 mm in-plane resolution for reliable depiction. Fat suppression is mandatory to see bone marrow oedema against the normal fatty marrow background. At TE 20–40 ms (PD range), the ligaments and cartilage are displayed at optimal signal. Magic angle effect is present in ligaments oriented at approximately 55° to B0 — primarily the oblique fibres of the plantar Lisfranc ligament; this should be verified on a T2-weighted sequence when PD signal increase is seen.

Sagittal PD-FS provides the longitudinal profile of each ray (metatarsal–cuneiform–navicular or metatarsal–cuboid column), displays the plantar fascia and plantar aponeurosis along its length, and characterises the navicular and cuboid in their long axis. Navicular stress fractures, cuboid fractures, and accessory ossicle synchondrosis are best characterised on sagittal images. The plantar fascia mid-foot origin at the calcaneal tuberosity and the mid-foot plantar soft tissues including the intrinsic muscles are assessed on sagittal sequences.

Axial PD-FS provides the cross-sectional anatomy of the mid-foot at each tarsal and TMT level. The peroneal tendons (peroneus longus and brevis) at their insertion on the cuboid and fifth metatarsal base, and the tibialis posterior at its insertion on the navicular tuberosity, are assessed primarily in cross-section on axial images. The dorsal Lisfranc ligament (separate from the interosseous) is seen on axial sequences at the level of the first–second TMT joints. The tarsal sinus and the mid-tarsal joints are assessed in cross-section.

Coronal T1 (without fat suppression) provides the anatomical complement for bone marrow characterisation. Normal yellow marrow appears bright on T1; any replacement process (infiltration, oedema, red marrow conversion, osteomyelitis, metastatic disease) appears T1-dark. The T1 provides the anatomical localisation for bone marrow signal changes identified on STIR and PD-FS. The cortical bone integrity and the trabecular pattern are also assessed on T1. T1 without fat suppression should always be acquired before contrast injection as it provides the pre-contrast baseline for enhancement characterisation.

STIR provides the most B0-field-independent bone marrow oedema screening sequence. At the off-isocentre positions typically used for mid-foot imaging in the supine patient, spectral fat suppression (CHESS/SPAIR) may fail in the distal and lateral foot, whereas STIR provides reliable fat suppression regardless of B0 homogeneity. STIR is particularly important for screening bone marrow oedema in stress reactions, early Charcot, and subacute osteomyelitis. The STIR TI is 150–175 ms at 1.5T and 200–230 ms at 3T.

As documented throughout the MRIninja protocol series: STIR is absolutely contraindicated post-gadolinium — the inversion pulse nulls the signal of gadolinium-enhanced tissue, producing false-negative results for enhancement.

4.4 Sequence Matching and Cross-Sequence Consistency

The three orthogonal planes must all be prescribed from the foot long axis — not from the body axes. This is the cardinal rule for mid-foot MRI, analogous to the ankle and other foot and toe protocols. If the coronal, axial, and sagittal planes are not defined relative to the actual foot axis (which varies between patients due to foot position and natural rotation in the scanner), the TMT joints will not be assessed in their true cross-sectional plane and small ligament visualisation will be degraded.

For serial examinations (stress fracture healing, Charcot activity monitoring, treatment response), the plane prescription angles must be reproduced. Document the foot axis angulation relative to the scanner coordinate system.

Post-contrast T1-FS sequences must use the same geometric prescription as the pre-contrast T1 for meaningful comparison and potential subtraction.

4.5 Fat Suppression — Region-Specific Technical Considerations

Fat suppression in mid-foot MRI faces the same off-isocentre challenge as the wrist, fingers, and ankle — but with an additional complication: the mid-foot is at the extreme distal end of the lower extremity, and in most clinical positioning setups (supine feet-first), it is 30–60 cm from isocentre where B0 homogeneity is poorest.

Dixon fat suppression is the preferred technique for all PD and T1 sequences in mid-foot MRI. Dixon's B0-independent mechanism provides uniform fat suppression across the entire foot FOV including the peripheral cortical-marrow interfaces, the dorsal and plantar subcutaneous fat, and the tarsometatarsal region — even in the supine feet-first position far from isocentre.

SPAIR is an acceptable alternative when the patient is in the Superman position at isocentre, where B0 homogeneity is adequate for spectral fat suppression. SPAIR should not be relied upon for mid-foot sequences in the supine feet-first position.

STIR is the most reliable fat suppression for bone marrow screening regardless of patient position, and is the preferred sequence for this purpose in the mid-foot protocol, supplementing Dixon-suppressed PD sequences.

CHESS/ChemSat: not recommended as the sole fat suppression strategy for mid-foot MRI in supine positioning. Regional fat suppression failures along the lateral foot and dorsal fourth–fifth TMT region are the typical failure pattern.

5. Optimisation Strategy

5.1 Artifact Reduction by Source

Off-isocentre fat suppression failure is the dominant technical challenge in mid-foot MRI. In the supine feet-first position, the foot is 30–60 cm from isocentre, where B0 homogeneity is poor. This produces regional fat suppression failures that are characteristic: the lateral foot (fifth metatarsal base and cuboid region), the dorsal fourth–fifth TMT region, and the plantar subcutaneous fat may all show incomplete fat suppression. The result is T1/PD bright fat signal in these regions that can simulate bone marrow oedema or mask true signal changes. Prevention: Dixon fat suppression as the standard technique for all PD and T1-FS sequences; STIR as the bone marrow oedema screening sequence (B0-independent); Superman position at isocentre when possible.

Motion artefact is the second most common cause of non-diagnostic mid-foot MRI. At the very high spatial resolution required for ligament and cartilage assessment (0.3–0.4 mm in-plane), even 0.5 mm of motion between acquisitions produces visible blurring. The lever arm effect from foot movement at the ankle joint amplifies subtle patient motion. Prevention: comprehensive foam immobilisation within the coil; patient counselling before scanning about the need for foot stillness; reduce individual acquisition time to ≤ 5 minutes; small field of view reduces the apparent displacement at any given motion magnitude.

Chemical shift artefact at cortical margins produces a bright or dark band at the bone cortex–marrow interface in the frequency-encoding direction at narrow bandwidth, simulating periosteal reaction or cortical disruption. This is particularly problematic at the metatarsal base cortices and the cuneiform surfaces. At 3T, wider bandwidth (300–500 Hz/px) reduces the chemical shift displacement below the pixel size. The direction of the shift changes when frequency and phase encoding directions are swapped — this can help identify artefactual versus true cortical signal changes.

Magic angle artefact in ligaments and tendons at TE < 40 ms (PD range): the interosseous Lisfranc ligament, the plantar Lisfranc ligament, and the peroneal tendons at their mid-foot insertions may show apparent signal increase when oriented at approximately 55° to B0. This is artefactual and disappears at TE > 60 ms. Always verify equivocal PD signal in a mid-foot ligament at a T2-weighted TE — true tears persist; magic angle disappears.

Susceptibility artefacts from surgical hardware are the primary cause of non-diagnostic post-operative mid-foot MRI. Lisfranc fusion screws, metatarsal base fixation plates, and TMT joint arthrodesis hardware produce localised signal loss that may completely obscure the TMT joint being assessed. At 3T, the signal void is 4× larger than at 1.5T. For post-operative mid-foot MRI with stainless steel hardware: use 1.5T; apply MARS techniques (STIR instead of fat-suppressed PD; widen bandwidth; reduce echo train if possible); document the degraded regions explicitly in the report.

5.2 Protocol Efficiency and Throughput

A complete mid-foot MRI with three orthogonal planes, T1, and STIR requires 25–35 minutes at 3T with standard hand/wrist coil. Adding post-contrast sequences extends this to 35–45 minutes.

For the majority of sports medicine indications (Lisfranc ligament assessment, navicular stress fracture, metatarsal base injury), three-plane PD-FS + coronal T1 + coronal/sagittal STIR in approximately 25 minutes is adequate. Contrast is not required.

For the diabetic foot / Charcot / osteomyelitis assessment, post-contrast T1 is mandatory and adds 8–10 minutes. DWI as an additional differentiating sequence adds 4–5 minutes.

3D isotropic PD-FS (SPACE/CUBE/VISTA) at 0.3–0.4 mm isotropic can replace the three 2D planes in a single 8–10 minute acquisition, providing multiplanar reconstruction capability — beneficial for Lisfranc ligament assessment where the oblique fibres require non-standard reformats. This approach is particularly useful at 3T where the SNR margin supports isotropic acquisition.

5.3 Field Strength Considerations

3T is the preferred field strength for mid-foot MRI. The higher SNR supports the 0.3–0.4 mm in-plane resolution required for small ligament (Lisfranc) and plantar plate assessment. At 3T, the 2-mm thick slices necessary for tarsal stress fracture detection are achievable with adequate SNR. Dixon fat suppression at 3T compensates for the greater B0 inhomogeneity at the off-isocentre foot position.

1.5T is clinically adequate and preferred for:

• Post-operative mid-foot with metallic hardware (significantly less susceptibility artefact)
• Patients where the imaging question can be answered at lower spatial resolution
• When 3T scanner access is limited

The key practical consequence: at 1.5T, target in-plane resolution is 0.4–0.5 mm (sufficient for Lisfranc assessment in most cases) versus 0.3–0.4 mm at 3T. Both achieve clinically diagnostic quality for the primary mid-foot indications.

6. Contrast Use Principles Specific to Mid-Foot MRI

6.1 Non-Contrast Standard Protocol — Sufficient For

Non-contrast mid-foot MRI (PD-FS three planes + T1 coronal + STIR) is diagnostically adequate for:

• Lisfranc ligament assessment (partial vs complete tear)
• Navicular stress fracture detection and characterisation
• Accessory ossicle synchondrosis assessment
• Tarsal coalition characterisation
• Mid-foot osteoarthritis and post-traumatic changes
• Tendon insertion assessment (tibialis posterior at navicular; peroneal at cuboid and fifth metatarsal base)
• Bone marrow oedema screening (stress reaction, post-traumatic contusion)

Contrast is not required for the majority of mid-foot sports medicine and traumatic indications.

6.2 Gadolinium Indicated — Region-Specific Contexts

Gadolinium-enhanced sequences are required or strongly useful for:

• Diabetic foot / suspected osteomyelitis: enhancement of cortical sinus tracts, enhancement of bone marrow in cortical-breach osteomyelitis, abscess rim enhancement, and differentiation from Charcot neuroarthropathy (which also enhances but with different spatial distribution)
• Active Charcot neuroarthropathy staging: diffuse periarticular enhancement; bone marrow enhancement helps assess activity
• Soft tissue mass characterisation: vascular malformation, tenosynovial giant cell tumour, fibrosarcoma — all require enhancement characterisation
• Inflammatory arthropathy with synovitis: synovial pannus enhancement; erosion characterisation
• Suspected septic arthritis of TMT joints: enhancement of pericapsular tissues and synovium
• Post-operative assessment with suspected hardware loosening or septic complications: enhancement pattern at the hardware-bone interface

6.3 Post-Contrast Acquisition Timing

For mid-foot inflammatory and infectious indications, standard post-contrast T1-FS sequences at 3–5 minutes after injection provide the equilibrium phase enhancement that characterises most mid-foot pathology. The enhancement of synovium, bone marrow, and soft tissue infection is maximal at this phase.

No specific early-phase or multiphasic timing is required for standard mid-foot applications. The pre-contrast T1 (coronal) must always be acquired before injection for comparison.

7. Reporting Essentials

7.1 Interpretation Framework

Mid-foot MRI reporting follows a compartmental approach, systematically assessing each anatomical compartment before synthesising a diagnostic conclusion:

Medial column (first metatarsal base → medial cuneiform → navicular): assess the first TMT joint, the first cuneonavicular joint, the navicular body (stress fracture zone: central 60%), the navicular tuberosity (tibialis posterior insertion), and the medial cuneiform.

Central column (second and third metatarsal bases → intermediate and lateral cuneiforms): the second TMT joint and the interosseous Lisfranc ligament at the medial cuneiform–second metatarsal base junction. The most critical joint and ligament in the mid-foot.

Lateral column (fourth and fifth metatarsal bases → cuboid): peroneus longus groove on the cuboid; peroneus brevis at the fifth metatarsal base (styloid process); cuboid stress fractures.

Plantar structures: plantar fascia mid-course; intrinsic muscles; plantar plate at TMT level.

Bone marrow survey: systematic STIR assessment of all tarsal bones and metatarsal bases for marrow oedema.

Soft tissues: subcutaneous fat; dorsal and plantar tendons; any mass or collection.

Broad diagnostic axes: acute vs chronic injury; ligamentous vs osseous primary pathology; inflammatory vs mechanical vs neuropathic; focal vs diffuse bone marrow changes.

7.2 Mandatory Reporting Checklist

Technical quality:

• [ ] Field strength and coil documented
• [ ] Fat suppression technique noted
• [ ] Motion artefacts or fat suppression failures limiting interpretation noted

Lisfranc complex (for appropriate indications):

• [ ] Interosseous Lisfranc ligament: intact / partial tear / complete disruption
• [ ] Dorsal Lisfranc ligament: intact / tear
• [ ] Plantar Lisfranc ligament: intact / tear
• [ ] First–second TMT joint: normal / widened / flake fracture

Bone marrow (all tarsal bones and metatarsal bases):

• [ ] Navicular: signal normal / oedema / stress fracture (location, completeness)
• [ ] Cuneiforms (medial, intermediate, lateral): normal / signal change
• [ ] Cuboid: normal / signal change / fracture
• [ ] Metatarsal bases (1–5): normal / signal change
• [ ] Accessory ossicle signal if present

TMT joints:

• [ ] Joint spaces: normal / narrowed / widened
• [ ] Subchondral signal: normal / oedema / sclerosis
• [ ] Joint effusion

Tendons:

• [ ] Tibialis posterior at navicular tuberosity: intact / signal change / avulsion
• [ ] Peroneus brevis at fifth metatarsal base: intact / tear / avulsion
• [ ] Peroneus longus at cuboid groove: intact / signal change

Soft tissues and plantar structures:

• [ ] Plantar fascia: normal / thickened / signal change at mid-foot
• [ ] Soft tissue collection / mass / sinus tract

Post-contrast (if acquired):

• [ ] Enhancement pattern (bone marrow, soft tissue, joint)
• [ ] Sinus tract enhancement

7.3 Structured Reporting

Reports must include: Indication (clinical question: injury mechanism, diabetes, chronic pain, etc.); Technique (field strength, coil, sequences, contrast if used); Comparison (prior imaging); Findings (organised by anatomical compartment as above); Impression (direct answer to clinical question; ligament classification; fracture description; Charcot/osteomyelitis differentiation); Recommendations (weight-bearing radiographs if not performed; CT for pre-surgical planning; clinical follow-up interval); Limitations (hardware artefact; fat suppression failure region).

7.4 Incidental Findings — Clinical Decision Framework

Usually benign: small ganglion cyst in the dorsal mid-foot; intermetatarsal bursitis < 3 mm; incidental accessory ossicle without signal change; mild subchondral sclerosis without pain history.

May require clinical correlation: accessory ossicle with bone marrow oedema and adjacent soft tissue signal — may represent symptomatic os tibiale externum or symptomatic os peroneum; mid-foot bone marrow oedema in an asymptomatic region — may indicate early stress reaction; small TMT joint effusion in a diabetic patient without Charcot symptoms.

Require explicit communication: unexpected sinus tract with cortical breach — deep infection; unexpected aggressive bone lesion features (cortical destruction, periosteal reaction, soft tissue mass) — primary bone tumour or metastasis; unexpected neuropathic joint changes in an undiagnosed diabetic patient — communication to referring clinician immediately.

8. MRI Technologist Pearls

8.1 Sequence Order Logic

Recommended acquisition order for standard non-contrast mid-foot MRI:

1. Three-plane body localiser
2. Dedicated foot localiser (foot-specific low-resolution coronal + sagittal) ← mandatory additional step unique to foot/toe protocols
3. Coronal PD-FS ← primary Lisfranc ligament and TMT joint sequence; acquire first while patient most compliant
4. Sagittal PD-FS ← navicular, plantar structures, mediolateral column assessment
5. Axial PD-FS ← tendon insertions, dorsal Lisfranc, tarsal sinus
6. Coronal T1 ← anatomical complement; less motion-sensitive
7. STIR (coronal or sagittal) ← bone marrow screen; always before contrast

8.2 Positioning Tricks

Superman position for patients who can tolerate it: place a small pillow under the abdomen to reduce lumbar lordosis; ensure the foot is dorsiflexed by 15–20° using a foam wedge under the toes (not the mid-foot — the wedge under the toes dorsiflexes the forefoot while keeping the mid-foot in contact with the coil floor).

For supine feet-first patients: tilt the coil gantry (if available) or use an angled foot rest to bring the mid-foot slightly closer to isocentre. A 5–10 cm elevation of the foot with a foam block under the heel improves coil coupling and reduces the distance to isocentre.

For the diabetic Charcot foot with deformity: the rocker-bottom deformity means the plantar surface is not flat. Foam wedges must be custom-shaped to the foot deformity to achieve stable positioning. The target FOV must be planned to account for the deformity — standard anatomical landmarks may not apply.

8.3 Fast Salvage Protocol

Three sequences in approximately 10 minutes provide the minimum clinically interpretable mid-foot MRI. T1 and axial plane can be added if the patient recovers compliance.

8.4 Common Avoidable Errors

9. Quality Control Checklist

• [ ] Dedicated foot localiser acquired before diagnostic sequences
• [ ] Coronal planes perpendicular to second metatarsal long axis (verified on sagittal localiser)
• [ ] All five TMT joints included in coronal coverage
• [ ] Navicular fully included (for navicular evaluation)
• [ ] Fifth metatarsal base and cuboid included in lateral coverage
• [ ] Fat suppression uniform across full mid-foot FOV — no regional failure (especially lateral foot)
• [ ] STIR acquired before contrast injection
• [ ] Motion artefacts assessed on coronal PD-FS (highest resolution — most sensitive to motion)
• [ ] T1 coronal acquired before contrast injection
• [ ] Post-contrast T1 acquired at stated timing (if contrast used)
• [ ] Phase encoding direction documented
• [ ] Laterality (left/right) correctly labelled
• [ ] All five mandatory sequences completed (or reason for omission documented)
• [ ] Magic angle check: any equivocal ligament PD signal verified on T2-weighted sequence

11. Evidence Gaps and Ongoing Debate

Optimal resolution threshold for Lisfranc ligament assessment: the interosseous Lisfranc ligament is 2–4 mm wide, but partial tears of the plantar component are at the detection threshold even with optimised protocols. No prospective study has defined the minimum in-plane resolution required for reliable complete versus partial Lisfranc tear classification with surgical correlation as reference standard.

3D isotropic vs 2D optimised sequences for mid-foot: the comparative diagnostic accuracy of 3D isotropic PD-FS (0.3–0.4 mm isotropic) versus 2D PD-FS (0.3 × 0.3 mm in-plane, 2 mm slice) for Lisfranc ligament and metatarsal base injury has not been prospectively evaluated in clinical series with surgical verification.

Charcot vs osteomyelitis differentiation: despite decades of research, the reliable differentiation of active Charcot from superimposed osteomyelitis on MRI remains an unresolved problem. Multiple MRI criteria have been proposed (sub-articular bone marrow distribution for Charcot; cortical breach and sinus tract for osteomyelitis; DWI restriction in acute infection) but their combination in a validated algorithm with reproducible thresholds does not exist. This is the primary clinical evidence gap in mid-foot MRI.

Role of DWI in mid-foot infection: preliminary data suggest DWI may help differentiate active osteomyelitis (high restriction) from Charcot (variable restriction), but prospective multicentre validation is lacking.

AI reconstruction for small extremity MRI: deep learning reconstruction (DLR) has been applied to knee and wrist MRI with validated results. Its specific validation for mid-foot MSK imaging — where in-plane resolution is at the detection limit for small structures — is not yet published in clinical series.

Gadolinium dose and timing optimisation for mid-foot infection: no specific study has established the optimal GBCA dose or post-injection timing for maximum osteomyelitis vs Charcot differentiation in the mid-foot. Standard timing (3–5 minutes) is based on general MSK principles rather than mid-foot-specific data.

12. Evidence-Based References

A. Guidelines / Consensus / Society Recommendations

(No dedicated society guideline exists specifically for mid-foot MRI protocol. The evidence base consists primarily of technical papers and anatomical studies.)

B. Systematic Reviews / Meta-analyses

C. Important Prospective / Original Studies

D. Technical MRI Papers

E. Landmark Historical References

End of document — MRI Mid-Foot Generic Standard Protocol — MRIninja v1.0 — May 2026

This master page is the reference for all future mid-foot MRI child pages including: Lisfranc ligament injury (partial vs complete); navicular stress fracture; Charcot neuroarthropathy vs osteomyelitis; tarsal coalition; accessory ossicle synchondrosis; mid-foot inflammatory arthropathy; plantar fascia mid-foot.