imaios mri ankle

Standard axial, coronal and sagittal planes are used in the ankle both on 1.5T and in 3T.In addition to the standard planes, a oblique scan is sometimes included oriented perpendicular to the peroneus and tibialis posterior tendons.The orientation of the tendons along the medial and lateral malleolus can cause the 'magic angle artifact' to occur.This artifact is visible on short TE images (f.e. Protocol specifics will Augmentation of T waves is observed at fields used in standard imaging but this side effect in MRI is completely reversible upon removal from the magnet . MRI with its multiplanar capabilities, excellent soft-tissue contrast, non-invasiveness and lack of ionizing radiation, has become a valuable tool in evaluating patients with foot and ankle problems. Clinical History: A 17 year-old female injured her right ankle 4 days ago during a soccer game.

An ankle MRI may be performed if a person has suffered a serious ankle injury.

In this article a systematic approach is presented on how to describe a standard MRI of the ankle.We use a checklist when evaluating an MRI of the Ankle:When you have evaluated all these structures, combine your findings and try to make a specific diagnosis.Start your exam with fatsat images of the bones to screen for edema.This patient has bone marrow edema on the posterior side of the distal tibia.On the axial image, the edema is localised around the insertion site of the posterior syndesmosis.The patient on the left has bone marrow edema in the medial malleolus.The patient on the right has edema in the medial talus.The bone marrow edema in these patients is due to avulsion injury on the insertion sites of the deltoid ligament.This patient has bone marrow edema in both the medial malleolus and the medial talus.The lateral ligaments also show edema and thickening.Stress fractures of the calcaneus are a frequently unrecognized source of heel pain.This patient has edema in the calcaneus as a result of a stress fracture.In those cases you may consider a CT-scan which can be more sensitive.This patient has multiple stress fractures of the calcaneus.In this patient there is very subtle edema in the distal fibula.When there is edema like in this case and no visible fracture line, you may consider CT.Do not mention the edema without having ruled out a fracture line on MR or CT.In this case there is a lot of edema in the navicular bone.The axial image nicely depicts the stress fracture.OCD is an abbreviation which can stand for either Osteochondritis Dissecans or Osteochondral Defect.Both describe a joint defect which involves the articular cartilage and the underlying subchondral bone.When a small defect in the chondral plate is present, the intraarticular fluid will erode the subchondral bone, which will result in bone marrow edema.In the foot and ankle many accessory ossicles can be seen.Compression of the os trigonum and surrounding soft tissues between the tibia and the calcaneus during plantar flexion can be a cause of posterior impingement.The term Stieda process is used, when the lateral tubercle is very prominent.This is an example of posterior impingement due to a symptomatic os trigonum.Here an example of an os trigonum with rather subtle edema.This case is shown to demonstrate the great variety of ossicles and tubercles on the posterior side of the talus.This patient has an unfused prominent lateral tubercle with a fibrous connection to the talus, therefore it is a partly fused os trigonum.Once you have studied the bones, scan the joints for effusion.The left image shows a normal fluid accumulation in the tibiotalar joint, talocalcaneal joint en retrocalcaneal bursa.The right image shows massive joint effusion as a reaction to degenerative osteochondral defects in the tibiotalar joint.Two examples of diffuse joint effusion in the tibiotalar joint.The capsule thickening can be posttraumatic or postoperative.On the right a patient who developed postoperative fibrosis after resection of a Haglund exostosis.In this patient there is only a small effusion in the ankle joint.On the fatsat images, you may think that there is only some edema in the subcutaneous fatty tissue.Capsular thickenig and soft tissue abnormalities are usually better seen on non-fatsat images.In this case there is fibrous thickening of the capsule (arrow).This patient has secundary degenerative changes in the joint with subchondral edema and cyst formation.Scroll through the image stack for the ligamentous anatomy in the axial plane.The syndesmoses are usually involved in exorotation injuries like:In A - a normal anterior syndesmosis is seen as a thin low intensity band.In B - the anterior syndesmosis is thickened with edema, indicating partial tearing or grade 2 injury.In C - the anterior syndesmosis is thickened and there probably is a focal discontinuity (arrow) and that is the reason why this was called a grade 3 injury (full thickness tear).Isolated injury of the anterior syndesmosis can be seen in low grade exorotation injuries.In this patient there is a full thickness tear of the anterior syndesmosis (yellow arrow).This patient had a Weber C fracture, which is a grade 4 pronation exorotation injury in the Lauge-Hansen classification.Acute injury presents as edema and thickening, while an old injury presents with thickening and low signal intensity due to scar formation.In A there is edema and thickening around the anterior and posterior syndesmosis (arrow), indicative of acute grade 2 injuries.In C there is scar tissue as a result of previous injury, which again can be a cause of posterior impingement.The ATFL runs from the lateral malleolus anteriorly to the lateral border of the talus.This is the most commonly injured ligament of the ankle and it is also the first to be injured on the lateral side.The patient on the left has subtle edema around the ATFL-ligament, while the ligament itself looks normal.The patient in the middle has thickening and architecture distortion representing a partial tear (grade 2).Here an example of a grade 3 ATFL tear with a bright rim sign (arrow).It is thought that it is caused by a chemical shift artifact when subcortical fatty marrow is exposed to joint fluid.The CFL runs from the distal fibula to the lateral side of the calcaneus and is best appreciated on coronal images.The CFL passes two joints, the talocrural joint and the talocalcaneal joint.The PTFL courses posterior to the lateral tubercle on the posterior aspect of the talus.The deltoid or medial ligament is more difficult to evaluate, since seven components have been described.The deltoid ligament is best evaluated in the coronal plane.The superficial layer of the deltoid ligament is connected to the navicular bone anteriorly and the calcaneus posteriorly.These images show injury to the deep deltoid ligament.The image on the right shows fiber discontinuity making it a full thickness or grade 3 tear.On these images we can recognize the close relationship between the deltoid ligament and the periosteum of the medial malleolus and the flexor retinaculum.On the image in the middle there is a deltoid ligament injury with separation of the periosteum or "periosteal stripping".On the image on the right there is thickening of the deltoid ligament with a low signal intensity as a result of chronic injury.Thickening of the periosteum is a common finding and indicates injury of the deltoid ligament in the past.The plantar fascia is a thick aponeurosis which supports the arch on the plantar side of the foot.Plantar fasciitis, the most common cause of heel pain in the athlete, is a low-grade inflammation involving the plantar aponeurosis and the perifascial structures.Spurring as seen on a X-ray therefore can be seen in symptomatic and asymptomatic patients.Tendinopathy is a collective term to describe different tendon disorders like tendinosis, tendinitis and mucoid degeneration.The pathogenesis of these disorders is different, but the clinical presentation and imaging features are not always distinctive.The achilles tendon does not have a tenosynovial layer but a paratenon.The posterior tibial tendon is the most commonly injured tendon.Posterior tibial tendon dysfunction is more common in women and in people older than 40 years of age.Posterior tibial tendon injury in young patients is mainly due to trauma or overuse.When the posterior tibial tendon is injured, be sure to check the spring ligmanent, since they together maintain the arch of the foot on the medial side.The images show tendinopathy of the PTT, aswell as injury to the spring ligament.The Achilles tendon is the largest and strongest tendon in the human body.Achilles tendinopathy is most likely due to a series of microtears that weaken the tendon and cause swelling of the tendon (image on the right).On sagital images the achilles tendon should be a straight line without any fluid around it and no focal thickening.Normally, a small amount of fluid is seen in the retrocalcanear bursa.This image shows fibrotic tissue anterior to the Achilles tendon (yellow arrow) after resection of a Haglund exostosis.This image shows an extreme case of insertion tendinopathy of the Achilles tendon.Rupture of the Achilles tendon usually occurs in the part of the tendon situated within 6 centimeters of the insertion to the calcaneus.The peroneus brevis tendon is injury-prone, because it is positioned inbetween the fibula and peroneus longus tendon.Once a small tear is initiated, it will results in a cashew nut deformity.In the middle and right we see two examples of cashew nut deformity, indicative of partial split rupture.This can be challenging, because the actual tear cannot be seen, only the architectural deformation.Split tears are associated with inversion injuries, most likely due to greater force on these tendons after ligamentous injury.Split tears of the peroneus longus are less common.Accessory muscles are frequently seen around the ankle joint.However when you compare the findings with the normal patient on the left, you will detect the big accessory soleus muscle.The patient on the right has a hypertrophic plantaris muscle.

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