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MR Imaging of the knee
Dr.Ajai Perti MD.
Chief Radiologist & Medical Director
Vita Diagnostics Ltd.
MR & CT Imaging Center...
Knee pathology
• Meniscal pathology
• Ligament injury
• Cartilage lesions
• Bony and tendinous lesions.
Technique
• Dedicated extremity coil
• Small FOV – 18 cm
• 4mm slices / 1mm gap
• 224 x 256 matrix
• Sequences : coronal T...
Meniscal anatomy
Lateral meniscus Medial meniscus
Grading of meniscal signal
Grade I : Globular intrasubstance increased
signal intensity, not extending to
articular surfac...
Grade I
Grade II
Grade III
Meniscal tear
• Horizontal
• Vertical
- Radial
- Longitudinal
- Oblique
• Complex
Radial tear
Radial tear at
meniscal root
Radial tear at
meniscal root
Longitudinal tear
Complex tear
Bucket handle tear
Anterior flipped horn
Discoid meniscus
• Dysplastic; Disc like configuration
• Commonly affects lateral meniscus
• Imaging:
- Radial diameter >1...
Discoid lateral meniscus
Parameniscal cyst
Pseudo meniscal tears
MR imaging accuracy
Sensitivity Specificity
Neg.pred.
value
Medial
meniscal tear 93-98% 84-91% >95%
Lateral
meniscal tear ...
Normal ACL
ACL avulsion
Mid substance tear
Proximal ACL tear
Interstitial tear
Chronic ACL tear
Cartilage erosions
in ACL tear
ACL ganglion cyst
Tibial tunnel determines
impingement
Femoral tunnel determines
isometry
Normal PCL
PCL injury
• Less common – 5-20%
• Associated with other injuries
Partial PCL tear Complete PCL tear
PCL avulsion
MCL injury
Grade I : Edema & hemorrhage superficial to lig.
Grade II : Displacement of lig. fibres from bone
Grade III : C...
Grade II
Grade I
Grade III
LCL tear
Posterolateral corner injury ……
O’Donoghue’s triad
MR imaging accuracy
Sensitivity Specificity
ACL tear 95-98% 73-88%
PCL tear 97-99% 80-95%
Tendon tears
Chondromalacia patella
• Softening of articular cartilage
• Common in young adults, can mimic meniscal tear
• Predisposing...
• Primarily affects male patients -
10 to 20 yrs
• Typically involves the lateral
surface of med.fem.condyle.
• H/o trauma...
Osteochondritis dissecans - Staging
Stage I : lesion 1-3cm ; intact cartilage
Stage II : Cartilage defect ; no loose body
...
Spontaneous osteonecrosis
• Older females , acute medial joint pain
• Subchondral sclerotic focus with marrow
edema, often...
Tibial stress fracture
Menisceal tears-a dilemma
• Grade-2 vs grade 3 signals –
• To distinguish articular surface extension of
the tears.
• Intrasubstance tear –at scopy ...
Contd….
• Transverse ligament-
• Anterior horns of medial & lateral
meniscus.
• Antero-lateral to LM - between tibial
atta...
contd….
• Fibrillation- Fraying of the free edge.
• Use fat sat images.
• FrayingMacerationImbibes synovial
fluidHigh s...
cont…
• Popliteus tendon-
• Sheath near the Posterior horn of LM 
Grade-3 signal  Tear.
• After lat. meniscectomy Popli...
contd. …
• Menisco-Femoral Ligaments-Anterior -Lig.
Of Humphrey- ant. to PCL-34%.
• Posterior -Lig. Of Wrisberg- post. to ...
Pseudo bucket-handle tear….
• Separate portions of PHLM-In corona
sections.
• Not seen with Medial meniscus.
• Look at Sag...
Lax meniscal sign….
• Lax or redundant meniscus- MM with
asso. EffusionMimics menisceal tear.
• Disappears with joint ma...
Others…..
• Vaccum Phenomenon-Intra-articular
gas Signal void Mimics tear.
• Pesudo loose body-Intercondylar notch
Low ...
Final Request….
• What the mind doesn’t know the eyes…….
• Radiologists do make mistakes even after
years of MR interpreta...
Thank you for your patience…..
Knee mri
Knee mri
Knee mri
Knee mri
Knee mri
Knee mri
Knee mri
Knee mri
Knee mri
Knee mri
Knee mri
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Knee mri

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Knee mri

  1. 1. MR Imaging of the knee Dr.Ajai Perti MD. Chief Radiologist & Medical Director Vita Diagnostics Ltd. MR & CT Imaging Centers, Cochin, Thrissur, Vaikom,Calicut
  2. 2. Knee pathology • Meniscal pathology • Ligament injury • Cartilage lesions • Bony and tendinous lesions.
  3. 3. Technique • Dedicated extremity coil • Small FOV – 18 cm • 4mm slices / 1mm gap • 224 x 256 matrix • Sequences : coronal T2*, STIR, sagittal T1, T2, T2*, axial T2 ; optional PD / T1 3D GRE fat sat.
  4. 4. Meniscal anatomy
  5. 5. Lateral meniscus Medial meniscus
  6. 6. Grading of meniscal signal Grade I : Globular intrasubstance increased signal intensity, not extending to articular surface. Grade II : Linear , may communicate with capsular margin. Grade III : Sharp linear, extending to articular surface
  7. 7. Grade I Grade II Grade III
  8. 8. Meniscal tear • Horizontal • Vertical - Radial - Longitudinal - Oblique • Complex
  9. 9. Radial tear
  10. 10. Radial tear at meniscal root
  11. 11. Radial tear at meniscal root
  12. 12. Longitudinal tear
  13. 13. Complex tear
  14. 14. Bucket handle tear
  15. 15. Anterior flipped horn
  16. 16. Discoid meniscus • Dysplastic; Disc like configuration • Commonly affects lateral meniscus • Imaging: - Radial diameter >12mm - Visualised in 3 or more sag. Slices - Loss of tapering
  17. 17. Discoid lateral meniscus
  18. 18. Parameniscal cyst
  19. 19. Pseudo meniscal tears
  20. 20. MR imaging accuracy Sensitivity Specificity Neg.pred. value Medial meniscal tear 93-98% 84-91% >95% Lateral meniscal tear 80-96% 91-99% >95%
  21. 21. Normal ACL
  22. 22. ACL avulsion
  23. 23. Mid substance tear
  24. 24. Proximal ACL tear
  25. 25. Interstitial tear
  26. 26. Chronic ACL tear
  27. 27. Cartilage erosions in ACL tear
  28. 28. ACL ganglion cyst
  29. 29. Tibial tunnel determines impingement Femoral tunnel determines isometry
  30. 30. Normal PCL PCL injury • Less common – 5-20% • Associated with other injuries
  31. 31. Partial PCL tear Complete PCL tear
  32. 32. PCL avulsion
  33. 33. MCL injury Grade I : Edema & hemorrhage superficial to lig. Grade II : Displacement of lig. fibres from bone Grade III : Complete lig. discontinuity.
  34. 34. Grade II Grade I Grade III
  35. 35. LCL tear
  36. 36. Posterolateral corner injury ……
  37. 37. O’Donoghue’s triad
  38. 38. MR imaging accuracy Sensitivity Specificity ACL tear 95-98% 73-88% PCL tear 97-99% 80-95%
  39. 39. Tendon tears
  40. 40. Chondromalacia patella • Softening of articular cartilage • Common in young adults, can mimic meniscal tear • Predisposing – Trauma, patellar malalignment, subluxation , PCL injury etc.
  41. 41. • Primarily affects male patients - 10 to 20 yrs • Typically involves the lateral surface of med.fem.condyle. • H/o trauma in 50% Osteochondritis dissecans
  42. 42. Osteochondritis dissecans - Staging Stage I : lesion 1-3cm ; intact cartilage Stage II : Cartilage defect ; no loose body Stage III : Partially detached ost.chond fragment Stage IV : Complete separation ; loose body +
  43. 43. Spontaneous osteonecrosis • Older females , acute medial joint pain • Subchondral sclerotic focus with marrow edema, often involving med.femoral condyle
  44. 44. Tibial stress fracture
  45. 45. Menisceal tears-a dilemma
  46. 46. • Grade-2 vs grade 3 signals – • To distinguish articular surface extension of the tears. • Intrasubstance tear –at scopy - may need probing. • Effusion- If present – disrupted menisceal surface.
  47. 47. Contd…. • Transverse ligament- • Anterior horns of medial & lateral meniscus. • Antero-lateral to LM - between tibial attachment of ACL and Infra patellar fat pad. • Seen in 40% pts. • Simulates an oblique tear of LM.
  48. 48. contd…. • Fibrillation- Fraying of the free edge. • Use fat sat images. • FrayingMacerationImbibes synovial fluidHigh signal on T2WIMimics a tear.
  49. 49. cont… • Popliteus tendon- • Sheath near the Posterior horn of LM  Grade-3 signal  Tear. • After lat. meniscectomy Popliteus Retained post.horn remnant.
  50. 50. contd. … • Menisco-Femoral Ligaments-Anterior -Lig. Of Humphrey- ant. to PCL-34%. • Posterior -Lig. Of Wrisberg- post. to PCL- 60%. • Fat bet. Post horn of LM and MF ligament Mimics vertical tear in post.horn of LM.
  51. 51. Pseudo bucket-handle tear…. • Separate portions of PHLM-In corona sections. • Not seen with Medial meniscus. • Look at Sagittal images.
  52. 52. Lax meniscal sign…. • Lax or redundant meniscus- MM with asso. EffusionMimics menisceal tear. • Disappears with joint manipulation.
  53. 53. Others….. • Vaccum Phenomenon-Intra-articular gas Signal void Mimics tear. • Pesudo loose body-Intercondylar notch Low signalMimics a loose body. • MCL bursa- bet. MM and MCL  Menisco-capsular tear.
  54. 54. Final Request…. • What the mind doesn’t know the eyes……. • Radiologists do make mistakes even after years of MR interpretation…. • Follow ups are of great help to improve the diagnostic accuracy…..!!!!
  55. 55. Thank you for your patience…..

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