MRI anatomy of ankle radiology ppt pk is nice presentation that covers cross sectional anatomy as well as relevant anatomy from standard radiology book like CT MRI whole body by Hagga . cross section of mri is taken from mrimaster.com. This will help for radiology resident as well radiographers.

1. MRI ANKLE
Dr Pradeep Kumar

2. Introduction
• MR imaging has increased the scope for the diagnosis and treatment of
many ankle and foot diseases.
• Many abnormalities in the bones and soft tissue are demonstrated much
earlier on MRI before they become evident on other imaging modalities.
• Excellent soft tissue resolution, noninvasive nature, multiplaner capabilities
of MR imaging make it valuable for the detection and assessment of a
variety of soft tissue disorders of ligaments, tendons and other soft tissue
structure.
• MR imaging is useful for detection and assessment of bone contusion,
stress and insufficiency fractures and bone marrow edema.
• MR imaging is an important tool in evaluation of ankle ligament injury.

3. Imaging technique:
• Axial, coronal, sagittal planes parallel to the table top.
• The patient is supine with foot is about 20 deg of planter flexion.
Planter flexion is useful for : 1) for decrease the magic angle effect. 2)
it accentuates the fat plane b/w the peroneal tendons. 3) it allows
better visualization of calcaneofibular ligament.
• Extremity surface coil is used to enhance spatial resolution. Usually
12-16 cm FOV is used with a matrix of 256-512, 3-5 mm section
thickness with 1mm interval are usually preferred.
• Marrow abnormalities are best evaluated with T1 and STIR seg.

6. Imaging protocol
• T2 Fat suppressed/Inversion recovery- axial coronal saggital
• Fat suppressed fse pd
• T1 saggital
• When the tendons are the site of clinical concern --- PD-weighted
images along with T2-weighted sequences in the straight axial and
oblique coronal planes
• Tears in the substance of the ankle tendons are usually best seen with
PD-weighted images

7. • Ankle joint is hinge type of synovial joint formed by the articular
surfaces of distal tibia, fibula and talus.
• Ankle joint is surrounded by joint capsule strengthened by ligaments
and surrounded by tendons. The capsule is attached superiorly to the
articular surface of tibia and malleoli , inferiorly to the talus around its
upper articular surface.
• Ankle joint are divided into medial, lateral and syndesmotic groups.
• Tendons around ankle are divided into anterior , posterior and lateral
groups.

8. Normal tendon anatomy:
• Appears as low signal intensity structures on all sequences. T1 WI
provides good anatomic details, whereas T2 WI are useful for
assessing pathology. Any increased signal intensity on T2 WI indicates
presence of pathology.
• Magic angle effect produces increased signal within normal tendons .
When they form an angle of about 55 deg with main magnetic vector.
Commonly seen in PD and GRE sequences in tibialis posterior tendon
at its navicular bone insertion. To minimize magic angle effect foot is
20 deg planter flexed.

11. Anterior ankle tendons:
• There are four tendons from medial to lateral –TA, EHL,EDL,PT. These
tendons serves as dorsiflexors of foot and ankle.
• They are seldom affected with tibialis anterior being most commonly
involved.

12. Medial ankle tendons:
• Tibialis posterior attaches to navicular , cuniform and base of 1st-4rt
metatarsal. Tibialis posterior tendon provides support to longitudinal
arch of foot and injury can cause flat foot.
• Flexor digitorum longus passes lateral to tibialis posterior tendon and
inserts to distal phalanges of 2nd-5th toes.
• Flexor halluces longus passes beneath sustentaculum talus and insert
into base off 1st toe distal phalanx. Sheath of FHL tendon
communicates with ankle joint and fluid within sheath is common.

14. Medial aspect
Tendon: Tibialis posterior
Flexor digitorum longus
Flexor H. longus
Ligaments: Deltoid ligament

15. Posterior ankle tendons:
• Achilles and plantaris tendons are located in midline of posterior ankle and is
largest tendon in the body, diffusely low in signal intensity. Usually has flat or
concave anterior margin on axial images. Becomes convex when diffusely
thickened. Normally tendon measures 7 mm in AP-diameter.
• Does not have tendon sheath so cannot have tenosynovitis, but have paratenon
so Para-tendinitis can occurs. Paratenon is seen as thin line of intermediate signal
intensity on axial images.
• Plantaris lies anteromedial to Achilles tendon with high signal intensity fat plane
between.
• Tear of Achilles tendon occurs 4cm above the calcaneus insertion or at
musculotendinous junction.
• Retro-calcaneal bursa is located b/w the tendon and posterior aspect of
calcaneous, whereas tendoachilles bursa is located posterior to tendon in
subcutaneous fat.

17. Lateral ankle tendon:
• Peroneus brevis and peroneus longus tendons pass posterior and
inferior to lateral malleolus in the retro-malleolar groove.
• Peroneus brevis is flatter and broader lies anterior to longus, whereas
peroneus longus is posteriolateral and is more rounded. Peroneal
tendons are held inplace by superior retinaculum.
• Split tears are common in brevis.
• Peroneal tendons can sublux or dislocate , whenever there is tear of
superior retinaculum. Diagnosis is made if tendons are located lateral
to distal fibula rather than posterior to it. Hypoplastic retromalleolar
groove can predispose to subluxation.

20. Normal Ligamentous anatomy:
• On MRI ligaments appear as a thin low signal intensity structure
between adjacent bones , becoming apparent due to adjacent high
signal fat.
• Many of the ligaments appear heterogenous due to interposition of
fat especially the posterior talo-fibular ligament and tibio-talar
component of deltoid ligament.

22. Syndesmotic ligament:
• Between distal tibia and fibula.
• Anterior syndesmosis: Anterior-inferior-tibio-fibular ligament (AITiFL)
is basically connecting Chaput tubercle of tibia to Wagstoffes tubercle
of fibula.
• Middle syndesmosis: Interosseous tibiofibular ligament.
• Posterior syndesmosis: Triangular shaped poster-inferior-tibio-fibular
ligament (PITiFL).

24. Lateral collateral ligaments:
• Anterior-talo-fibular ligament (ATaFL) appears as thin linear band
extending from talus to lateral malleolar tip. ATaFL is most commonly
injured.
• Posterior-talo-fibular ligament (PTaFL) has fan shaped insertion
demonstrating marked heterogenicity.
• Calcaneo-fibular ligament (CFL) seen as low signal intensity band runs
obliquely downwards between bone and peroneus tendon.
• Very rare that calcaneofibular ligament injury alone is seen, it is
always associated with ATaFL injury.

26. Medial Deltoid complex:
• Deltoid complex separated into superficial and deep layers.
• Deep layer demonstrates a striated appearance and extends from medial
malleolus to medial surface of the talus.
Divided into 1) Anterior tibio-talar ligament (Difficult to visalise)
2) Posterior tibio-talar ligament (always identified on every MR)
• Superficial layer has three bundles they are typically fused.
1) Tibio-navicular ligament: most anterior ligament, not always identifiable. Runs
from most anterior aspect of anterior colliculus to downwards and inserts into
navicular bone.
2) Tibio-spring ligament: from anterior colliculus to going downwards and inserting
into superomedial part of spring ligament.
3) Tibio-calcaneal ligament: from intercollicular groove running downwards into
stantacular tali of calcaneum.

28. Spring ligament complex:
• Aka calcanio-navicular ligament.
• Is a stabilizer of medial longitudinal arch.
• Has three components based on insertion
on navicular bone
1) Superomedial band: connecting
stanticulum of calcanium to superomedial
aspect of navicular bone. In between
posterior tibial tendon and medial head of
talus.
2) Medioplanter oblique band.
3) Inferoplanter longitudinal band.

29. Tarsal tunnel :
• Fibro-osseous tunnel located on medial side of ankle and hind foot
extending from medial malleolus to navicular bone.
• Talus and sustentaculum tali forms lateral wall and medially by flexor
retinaculum and abductor hallucis muscle.
• Contents: Posterior tibila N/A/V, tibialis posterior, FDL, FHL tendons.
• Syndrome can arises from abnormalities intrinsic or extrinsic to
tunnel.

31. Os trigonum :
• Is common accessory ossicle located behind the talus at the posterior
end of subtalar joint.
• Develops as a separate ossification center.
• During growth it fuses to talus in most cases but in 5-15% it remain
ununited.
• Diagnosis can be made by demonstrating marrow edema in os-
trigonum and the adjacent talus.

33. Os peroneum:
• The os peroneum is a common sesamoid bone located in the
peroneus longus tendon as it passes under the
cuboid. Painful os peroneum syndrome presents with marrow edema
of the ossicle with surrounding soft tissue edema, best shown with
a luid-sensitive MRI sequence targeted to the lesion

34. Os peroneum syndrome

35. Sinus Tarsi :
• Lateral Cone shaped space between talus and calcaneus.
• Contains fat, ligament, neurovascular structures and portion of the
posterior subtalar joint capsule.
• Replacement of normal sinus fat by low signal intensity material on
T1WI and low/high T2 can be associated with tear of ATFL, CFL.

38. • We use a checklist when evaluating an MRI of the Ankle:
• Bones: screen on fatsat images for bone marrow edema.
• Joints: screen for effusion and look at the joint capsule for thickening.
• Ligaments: check the syndesmosis, the lateral and medial ligaments.
• Tendons: check the tendons using the four quadrant approach;
• Flexors on the medial side.
• Achilles tendon posteriorly.
• Peroneal tendons on the lateral side.
• Extensors on the anterior side.
• When you have evaluated all these structures, combine your findings and
try to make a specific diagnosis.

59. Thank You