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Musculoskeletal MRI

Musculoskeletal MRI. Goals. What types of MR studies are available for evaluation of the musculoskeletal system? Considerations when ordering a study

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Musculoskeletal MRI

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  1. Musculoskeletal MRI

  2. Goals • What types of MR studies are available for evaluation of the musculoskeletal system? • Considerations when ordering a study • Remember one of the roles of the radiologist is as consultant to work with you in determining the best study for the patient’s needs (it’s in the job description)… talk to them! • Most common pathologies for which MSK MRI is performed

  3. Exam Types • MRI without contrast • Most common • Evaluation of ligaments, tendons, occult fracture, cartilage • MRI with contrast • Evaluation of bone or soft tissue tumor, osteomyelitis, abscess • MR Arthrogram • Evaluation of labrum, intercarpal ligaments

  4. Body Part • When ordering any study must have a ddx in mind, particularly with MRI (not a screening tool) • Cannot perform an MRI of a whole extremity (time, pt motion, protocol issues) • Must identify part to be imaged – be specific • A joint, a bone (prox, mid, distal), a muscle (origin, belly, insertion) • Must have plain radiograph

  5. Most Common Indications • Occult fx or stress fx • Early osteonecrosis – in pt with risk factors & pain, known AVN of one hip • Osteomyelitis – plain film is insensitive (30-50% loss of bone density) BUT necessary for MRI interpretation, nucs has poor resolution • Osteochondral lesion – evaluate stability • Ligament/tendon injury – knee, shoulder, ankle > other jts • Bone tumor – MUST HAVE X-RAY 1st, imperative in providing ddx on MRI (dx on x-ray, determine extent on MR) • Soft tissue mass/muscle injury

  6. Considerations when ordering an MRI • Joint replacement in joint of interest – don’t do it • Pacemaker – don’t do it • Claustrophobia - sedation • Unable to hold still/follow instructions – sedation • Metal in area of interest (susceptibility artifact) – consult radiologist, may vary technique or recommend another study • Metal not in area of interest ie. orbits (motion, overheating) • If you only remember one thing, remember this: • cannot do a PE protocol chest CT without contrast

  7. Metal Artifact Small metal foreign body results in large area of signal void. Metal or gas = black hole.

  8. General Principles • Fluid, edema, inflammation is bright on T2 • Fat is bright on T1 & T2 (can have fat sat) • Blood is often bright on T1 • Tendons & ligaments are black on all sequences • Cartilage is bright on T2 • Muscle is intermediate in signal

  9. Pelvis & Hip – Normal Anatomy • Joints – sacroiliac, pubic symphysis, hips • Tendons – iliopsoas, gluteal, hamstrings, rectus femoris • Bursa – trochanteric, iliopsoas • Bones – evaluate for bone marrow replacing process (MM, mets), AVN, occult or stress fx • Acetabular labrum – need intra-articular gadolinium

  10. Femoral Head Osteonecrosis • Groin pain • Many predisposing factors: trauma (fem neck fx, dislocation), steroids, SLE, sickle cell dz, pancreatitis, alcohol abuse, Gaucher’s dz • Increased risk of contralateral AVN, must evaluate other side, most sensitive study is MRI • MRI: • Early – bone marrow edema • Later – geographic area of abnormal signal in the anterosuperior femoral head; double line sign on T2 • Even later – subchondral collapse, femoral head collapse, degenerative joint dz

  11. Femoral Head Osteonecrosis

  12. the other hip – 40% bilateral Anterior and superior femoral head

  13. More examples of AVN

  14. and more… Triple line sign?

  15. Labral Tear • Clicking, locking, pain with pivoting/twisting • Traumatic (young), degenerative (older) or assoc. with femoroacetabular impingement (middle-aged) • MRI: • Anterosuperior or posterosuperior • Linear high T2 signal • Loss of triangular morphology • Paralabral cyst • MR arthrogram most sensitive study – contrast fills tear

  16. Knee – Normal Anatomy • Anterior & posterior cruciate ligaments • Medial & lateral menisci • Medial collateral ligament • Lateral ligamentous complex (lateral collateral, iliotibial band, biceps femoris) • Extensor mechanism • Normal variant (discoid meniscus)

  17. Knee – Normal Anatomy

  18. ACL Tear • Sports injury, rapid stopping/starting/pivoting (skiing, soccor, football, basketball etc), anterior drawer sign on PE • MRI: • Disruption of fibers, high signal on T2 • Pivot-shift contusions • Anterior translation of tibia relative to femur • Associated with MCL and medial meniscus injury – O’Donahue’s unhappy triad • Associated with Segond fx (avulsion of mid third lateral capsular ligament from lateral tibial plateau)

  19. ACL Tear

  20. ACL Tear – Pivot shift contusion

  21. PCL Tear • Dashboard injury of flexed knee, posterior drawer sign on PE • MRI: • Disruption of fibers/thickened fibers • Abnormal high T2 signal • Avulsion at insertion on posterior tibia

  22. PCL Tear

  23. Meniscal Tear • Joint line tenderness, clicking, locking • MRI: • High T2 signal in the meniscus extending to the articular surface • longitudinal, radial, flap (flipped), oblique, bucket-handle • Parameniscal cyst

  24. Oblique Undersurface Tear w/ Parameniscal Cyst

  25. Bucket-handle Tear • Medial > lateral • Diminutive meniscus • Inner edge of meniscus is displaced medially into notch • Double PCL sign

  26. Bucket-handle Tear

  27. Discoid Meniscus • Predisposes to early degeneration and tear of meniscus • Lateral >> medial • MRI: • Large meniscus, no longer C-shaped • Bowtie should not be seen on ≥3 consecutive sagittal images (4mm)

  28. Discoid Meniscus

  29. Medial Collateral Ligament Tear • Valgus stress • Complete or partial tears affecting superficial and/or deep fibers • MRI: • Disruption of fibers with thickening & abnormal high signal • Associated with ACL & medial meniscal tears • Pellegrini-Stieda lesion – ossification at origin of MCL indicative of old tear

  30. Medial Collateral Ligament Tear • Pellegrini-Stieda lesion • Indicates old MCL tear • Ossification at origin of MCL from medial femoral condyle

  31. Acute on chronic MCL tear

  32. Patellar Tendon Tear • Partial or complete • Most commonly in proximal third of tendon at inferior pole of patella • Plain film: • patella alta • MRI: • Disruption of fibers, thickening & abn signal • Fluid-filled gap, hemorrage or granulation tissue

  33. Patellar Tendon Tear

  34. Patellar Tendon Teardifferent patient

  35. Jumper’s Knee (Patellar Tendinosis) • Repetitive trauma • MRI: • Proximal third of patellar tendon (posterior fibers) • Early – edema in peritenon • Later - thickening & edema (inc T2) • Even later – partial or complete tear • +/- reactive osteitis in lower pole patella (edema) • Reactive edema in adjacent fat pad

  36. Jumper’s Knee

  37. Jumper’s Knee

  38. Osteochondral Lesion • Young male, 50% have h/o trauma • Lateral aspect of medial femoral condyle, talar dome, capitellum • Plain film: area of sclerosis or bone/cartilage fragment in situ or defect with loose body in joint • MRI necessary to determine stability and guide treatment (stable-heal spontaneously, unstable-surgery) • MRI: • Fragment composed of hyaline articular cartilage and underlying subchondral bone • Unstable if fluid between fragment and donor site on T2

  39. OCD

  40. OCD

  41. Ankle – Normal Anatomy • Joints – tibiotalar, distal tibiofibular, subtalar (ant, middle, post), intertarsal • Tendons – flexor (tibialis posterior, digitorum longus, hallucis longus), extensor (tibialis anterior, hallucis longus, digitorum), peroneus (longus, brevis), Achilles • Ligaments – medial (deltoid), lateral (talofibular, talocalcaneal), syndesmotic, Lis-Franc • Muscles, bones, plantar fascia • Normal Variants – plantaris, accessory soleus

  42. Tarsal Coalition • Lack of segmentation of two tarsal bones • Most commonly calcaneonavicular or talocalcaneal (middle subtalar joint) • 20% bilateral; pain, flat foot • Cartilaginous, fibrous, osseous • Plain film: anteater sign, continuous C sign, talar beak, pes planus • MRI: • Cartilaginous, fibrous or bony bridge between 2 tarsal bones • Fibrous/cartilaginous - JSN, irregularity, sclerosis, bone marrow edema • Bony – continuity of bone marrow and cortex

  43. Talocalcaneal Coalition

  44. Calcaneonavicular Coalition

  45. Calcaneonavicular Coalition

  46. Accessory Soleus Muscle

  47. Accessory Soleus

  48. … and OCD Stable or unstable?

  49. Peroneus Brevis Split Tear • Peroneus brevis is normally round and anterior to longus • Tear most commonly at level of lateral malleolus • MRI: • C-shaped tendon • Longitudinal split, peroneus longus may be interposed between two subtendons • +/- fluid in tendon sheath (tenosynovitis)

  50. Peroneus Brevis Split Tear Tom Talar dome Dick Harry Peroneus tendons Achilles

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