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MRI of the Ankle and Hindfoot UCSD MRI Review Winter 2001

MRI of the Ankle and Hindfoot UCSD MRI Review Winter 2001. Steven S. Eilenberg, MD Director of MRI North County Radiology Assistant Clinical Professor UCSD. Imaging Techniques Grouping Concept The Ligaments The Tendons The Bones and Joints. Hinterlands Sinus Tarsi & Tarsal Tunnel

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MRI of the Ankle and Hindfoot UCSD MRI Review Winter 2001

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  1. MRI of the Ankle and HindfootUCSD MRI ReviewWinter 2001

  2. Steven S. Eilenberg, MDDirector of MRINorth County RadiologyAssistant Clinical ProfessorUCSD

  3. Imaging Techniques Grouping Concept The Ligaments The Tendons The Bones and Joints Hinterlands Sinus Tarsi & Tarsal Tunnel Some Interesting Cases Topics of Discussion

  4. Ankle and Hindfoot • Taken for Granted Unless Diseased • Little Respect • Training Programs • Imaging Centers • Referring and Treating Docs • Very Complex but Manageable

  5. Ligament Injuries Tendon Pathology Bony Pathology Fractures / Bruises Stress Reaction / Fractures Infection Infarction Tumor Idiopathic Marrow Edema Joint Pathology Osteoarthritis Infection / Inflamm Joint Bodies & OCD Instability Coalitions Common Conditions

  6. Soft Tissues Plantar Fasciitis Sinus Tarsi Syndrome Anterolateral Impingement Ganglia Tumor Infection Inflammatory Neural Entrapment Morton Neuroma Tarsal Tunnel Common Conditions

  7. Protocoling 101 • Develop Protocol Consensus • Protocols Should be Complete Enough to Encompass Most Conditions You Encounter • Avoid Multiple Protocols for Same Region • Talar Dome v Tendon/Achilles v Ligament v Plantar Fascia v Stress Fx v etc. • Why? • Symptoms Nonspecific • Disease Grouping

  8. Benefits of Inclusive Protocols • More Consistent Exam Quality • Fewer Callbacks • Greater Familiarity with Anatomy if Presented Same Way Each Time • Better Interpretations • Happier Technologists

  9. Imaging of Ankle and Hindfoot • Straight Axial v 20 Degree Plantar Flexion • Appropriate Localizer • Strive for Anatomical Orthogonal Planes • Define Coronal Axial Sagittal WRT Anatomy • Use Axial to Prescribe Sag and Cor • Image in at Least Three Planes • T1 In Three Planes • Long TR Sequence Matching in Three Planes

  10. Imaging of Ankle and Hindfoot • Smallest Coil Possible • Isocenter • Image Only Affected Foot/Ankle • Use Atlas • Include Heel Pad on Cor and Sag • Navicular Through Achilles on Cor • Include Plantar Fascia on Axials

  11. Imaging of Ankle and Hindfoot • T1 Sequence Suggestion: • Conventional T1 v FSE T1 (Both OK) • 3-5 mm Thick. 1 mm Gap. High Res Helps • Long TR Sequence Suggestion: • FSE Fat Sat PD or Lightly T2 weighted • FSE STIR with Reduced TI • Generally Avoid 2-D GRE • 3-D GRE if Using Workstation

  12. Ankle Sprains Injury to Talar Dome OCD, Osteoarthritis Instability Ankle Osteoarthritis Subtalar Osteoarthritis Injury to Intertarsal Ligament Instability Sinus Tarsi Syndrome Disease Grouping

  13. Disease Grouping • Injury To Tendons • Tendinosis • Local Inflammation • Effusion • Tarsal Tunnel Syndrome • Tearing • Instability • Loss of Arch • Plantar Fascia Stress • Subtalar Joint OA • Sinus Tarsi Syndrome

  14. Three Groups Syndesmotic Group Interosseous Tibiofibular Group Lateral Collateral ATFL CFL PTFL Medial Collateral Complex (Deltoid) 5 Bands or… Can Group into Deep (Short ACL) Superficial Ankle Ligaments

  15. Syndesmotic Group • Anterior and Posterior Tibiofibular Ligaments • Interosseous Ligament • Complex Tears - “Run in a Stocking” • Horrific and Unstable Injuries. Need ORIF. • Often See Ankle and Proximal Fibular Fxs • Best Seen on Axial Images, T1 and Fat Suppressed

  16. The Lateral Collateral Ligaments • Injuries Progress from Anterior to Posterior (As a Rule) • ATFL • Most Commonly Injured • Most Inferior Ligament, Tip of Fibula to Talus • Slight Caudal Angulation • Grade I, II, III

  17. ATFL And Anterolateral Impingement • Common Cause of Chronic Lateral Pain • Usually Result of Multiple Reinjuries • Synovial Hypertrophy and Granulation Tissue • Smudgy, Increase in Soft Tissue in Region of ATFL • Arthroscopic Debridement May Relieve

  18. Those Other LCLs • Calcaneofibular Ligament • Cord-like Structure Deep to Peroneus Tendons • Harder to See. Oblique on Axial and Coronal • Look for it in All Planes • Advantage of High Res 3-D GRE and Workstation • Seldom Completely Tears

  19. Those Other LCLs • Posterior Talofibular Ligament • Seldom Torn. Last to be Torn • Normally Looks Fuzzy and Edematous • May Insert on Os Trigonum • Probably the Most Unrecognized Injury with Respect to this Ligament, Can Destabilize the Os Trigonum

  20. Os Trigonum Syndrome • Disease Can Be Either Bone or Joint Centered • May See OA, Effusion • May See High Signal in OT and Surrounding Tissue • Primary Source of Pain v Secondary • Example of Secondary: Irritation of FHL

  21. Medial Collateral Ligament Complex - Deltoid • Less Commonly Injured • Deep (2 Bands) and Superficial Group (3 Bands) • Concentrate on Deep Portion • Deep Portion Best Seen on Coronal Images • Superficial Group Well Seen on Axial and Coronal • Should Look Like A Short ACL • Injuries Look Like Injured ACL • Swelling Indistinct Discontinuous

  22. Destabilized HindFoot • May See Nothing Radiographically • May See Inexplicable Bone Marrow Edema • May See OA in Subtalar Joints • Most typically posterior STJ • May See Abnormal Signal in Sinus Tarsi

  23. Sinus Tarsi Syndrome • Note: Radiologists Don’t See Syndromes • “Nonarticular” Space Between Calc and Talus • Contains Interosseous Ligament, Neurovascular Structures, and Fat • Most Commonly See: • Fat In ST Replaced by Soft Tissue • May See Adjacent Bony Changes • Usually See Intact Interosseous Ligament

  24. The Talar Dome • Frequently Injured at Time of Sprain • Often Radiographically Occult • Equal Involvement Med. and Lat. Margins • Types Of Injuries • Bone Bruise • Chondral • Osteochondral (Adopt This Term) • Note: Don’t Use OCD for all Injuries

  25. Osteochondral Injury To The Talar Dome • May Be Radiographically Occult, Until Chronic • What Do You Need To Say? • Where, and How Big • Condition of Overlying Cartilage • Condition of Underlying Bone ( Partially v completely loose) • Presence of Joint Bodies • Presence of OA in Ankle • Complete Description Painlessly Stages the Lesion

  26. An Artifact to Know About • Magic Angle Phenomenon • Collagen Containing Structures Oriented At Or Near 55 Degrees with Respect to Magnet’s Bore • Artifact Comes and Goes as Approach and Leave the Magic Angle • Spurious Increase in Signal in Affected Structure • No Accompanying Size Change

  27. Magic Angle, Continued • Where is it Seen Most Commonly? • Tendons, Around the Malleoli • Posterior Horns of Menisci, esp. Lateral • Short Segments of Rotator Cuff • Short Segment of Glenoid Labrum • What Sequences Are Most Affected? • T1 and T2* GRE • Field Strength Dependent? • To some Degree, but Stronger at Low Field

  28. Mitigating Magic Angle • Most Important- Know About It • Uniformly Gray • Predictable Locations • No Change In Size of Affected Structure • Nonpersistance on Long TR Sequences • Try to Avoid Magic Angle, If Possible • Position Joint Differently

  29. The Tendons • What Can Happen To Them? • Inflammation Around Them (Tenosynovitis) • Peritendonitis if Not Tendon Sleeve (Achilles) • Degeneration and Tearing • Usually at Points of Friction (Around Malleoli) • Swollen (Grade I) • Thin (Grade II) • Disrupted (Grade III) • Splitting (Most Often Peronius Brevis- Usually Part of Grade II) • Subluxation / Dislocation • Tumors (Giant Cell and Ganglia)

  30. The Tendons You Need To Know • Lateral • Peroneus Brevis (Anterior) • Peroneus Longus (Posterior) • Medial • Tom Dick ANd Harry • Posterior Tibialis, Flexor Digitorum Longus, Flexor Hallucus Longus

  31. The Tendons You Need To Know • Anterior • Tibialis Anterior • Posterior • Achilles • Plantaris (Just Know that it is There)

  32. Lateral Tendons • Peroneus Longus and Brevis • Brevis More Anterior • Brevis More Commonly Diseased • Brevis Most Commonly Split • Rarely Torn Completely (Grade III) • May be Subluxed (Torn Retinaculum) • Disease May Follow Ankle Sprain

  33. Medial Tendons • Posterior Tibialis Most Important • PT usually 2-3 X Larger than FDL • Diseased if Much Smaller or Larger • PT Flairs Just Prior to Insertion, May Simulate Disease • FHL-Most Common with Effusion • Communication with Ankle Joint • Most Sensitive to Changes in Gait

  34. Anterior Tendons • Tibialis Anterior Tendon Most Commonly Diseased - Still Uncommon • Most Common Level of Disease at Ankle Joint • Seldom Grade III, Unless Bisected

  35. Posterior Tendons • Achilles Tendinopathy • Insertional (Enthesopathy) • Noninsertional (Degenerative v Traumatic) • 3-6cm Proximal to Point of Insertion • Loss Of Concavity • Fusiform Swelling • Signal Abnormality • Cavitation • Discontinuity • Remains Thick After Healed

  36. Achilles Tendon • No Tendon Sheath • Peritendonitis • Predictable Location in Pre-achilles Fat • Intermediate to High Signal • Indistinct

  37. Bone Injuries • Stress Reaction v Stress Fracture • Most Commonly Involves Tibia, Calcaneus, Navicular and Talus

  38. Bone Injuries • Talar Dome • Often Missed, Pain Attributed to a Bad Sprain • See Bone Bruises and Osteochondral Fractures • Do Some Bone Bruises Progress? Probably! • Lateral Pain – X ray Negative • Not Uncommon to see Anterior Process of Calcaneus and Adjacent Cuboid Bruised or Fractured • Generalized Pain – Common to See Subtalar Joint Bruise or Fracture

  39. Tarsal Tunnel Syndrome • Radiologists don’t See Syndromes • Pain and Paresthesia – Plantar Aspect Foot • Most Often Unilateral • Entrapment of Posterior Tibial Nerve or Branch in the Tarsal Tunnel • Retinaculum & Bone Defines This Space • FDL, Artery-Nerve, FHL- All Surrounded by Fat

  40. Tarsal Tunnel Neural Entrapment • Idiopathic 50% • Remainder Caused by • Scar Tissue • Ganglia • Tenosynovitis (Usually FHL) • Varicose Veins In TT • Other Masses, Including Neuroma, and Lipoma

  41. Plantar Fascia • Static and Dynamic Supporter of Longitudinal Arch • Repetitive Trauma & Mechanical Stresses to the Plantar Fascia (Aponeurosis) • Microtears – Healing – Retear – Thickening • Fasciitis Common in Runners and Obese, But bulk of Cases non Running Women • Plantar Fascial Spur Not Sufficient for Dx • Role Of MRI?

  42. MRI of Plantar Fasciitis • Study Should Include Coronals and Sagittals. Coronals are Best • T1 and Edema Sensitive Long TR Sequence • Normal Plantar Fascia (3 mm Thick)

  43. MR Findings- Plantar Fasciitis • Plantar Fasciitis • Most Common: Edema on Both Sides of PF • Common: Thickening of PF (>6mm) • Less Common: Increased Signal in PF and Adjacent Intrinsic Muscles of the Foot • Uncommon: Marrow Reaction at Point of Origin (Calcaneal Tuberosity) • Rare: Disruption

  44. Important Points • Establish Protocol Consensus • Inclusive Protocols • Strive for Anatomic Orthogonal Planes • Image in Three Planes • Use Smallest & Best Coil • Isocenter • Image Only One Foot at a Time – Use Atlas!

  45. Important Points • Favorite Sequences • FSE FS PD v STIR with Reduced TI • Disease Grouping Concept (Smoke and Fire) • Become An Expert with the ATFL • Adopt the Term: Osteochondral Injury • Concept of Destabilized Hindfoot • Magic Angle (Always be on the Lookout)

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