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1. CT SCAN AND MRI IN
ORTHOPAEDICS
MODERATED BY
DR. S.P.SAIKIA,ASSIST.PROF
PREPARED BY
DR. S.H.RANNA,PGT
01-06-2016

2. Introduction to CT
• Designed by Godfrey N.
Hounsfield to
overcome the visual
representation
challenges in
radiography by
collimating the X-ray
beam and transmitting
it only through small
cross-sections of the
body.

3. C.T. scan • CT scan machines uses
X-rays, a powerful form
of electromagnetic
energy.
• CT combines X radiation
and radiation detectors
coupled with a
computer to create
cross sectional image of
any part of the body.

4. PRINCIPLE OF C.T SCAN
• The internal structure of an object can be
reconstructed from multiple projections of the
object. (Radon 1917 mathematically).

5. Cont..
• Density at a given point on an image
represents the x-ray attenuation
properties within the patient along a line
between the x-ray focal spot and the
point on the detector corresponding to
the point on the image

6. Cont…
• CT scanning is a
systematic
collection and
representation of
projection data.

7. CT Scan Methodology

8. Cont..

9. Comparison of CT with Conventional
Radiography
• Conventional radiography suffers from the collapsing of
3D structures onto a 2D image.
• CT gives accurate diagnostic information about
the distribution of structures inside the body.

10. Cont..
• A conventional X-ray image is basically a
shadow. Shadows gives an incomplete picture
of an object's shape.

11. Generations
generation configuration detector beam Min scan time
first Translate -
rotate
1-2 Pencil thin 2.5min
second Translate -
rotate
3-52 Narrow fan 10sec
Third
Rotate- rotate 256-1000 Wide fan 0.5sec
fourth Rotate- fixed 600-4800 Wide fan 1sec
fifth Electron beam 1284 Wide fan
electron
beam
33ns

13. CT ARTHROGRAPHY
• Arthrography is introduction of contrast
agent positive contrast iodine iodide
solution negative contrast, air or
combination of both into the joint
space.
• Advantages:
– Simple
– Effective

14. CT scan of spine
Clinical value of CT without 3D
Bone structure +++
Facet arthritis +++
Disc prolapse +++
Symptomatic disc without prolapse ------
trauma +++
spondylitis ++
Tumor +++
Spinal stenosis(central) +++
Spinal stenosis (lateral) +++

17. Spinal canal stenosis

19. Disc prolapse

20. Fracture in spine

21. CT scan of pelvis

23. CT SCAN KNEE
indications of knee Arthrography
Fractures around knee
Preoperative planning
Meniscal lesion and discoid meniscus
Cartilage lesion
Synovitis and bursitis
Demonstration of bone cyst or tumors
Cruciate ligament tear
Collateral ligament tear

24. CT of knee

25. CT SCAN OF SHOULDER
INDICATIONS
PLAIN CT CT Arthrography
# of proximal humerus Labral lesion
Scapular # Imaging joint capsule
Glenoid fracture Rotator cuff pathology
Bony bankart lesion Biceps tendon pathology
Hill –Sachs lesion
Arthritis of GH joint
Arthritis of AC joint
Calcific tendinitis

26. 1) Glenoid
2) Humerus
3) Deltoid
4) Infraspinatus
5) Scapula
6) Supraspinatus
7) Clavicle
8) Subscapularis

27. CT SCAN OF ANKLE
indications
Plafond fracture
Trimalleolar fracture
Talus fracture
Calcaneus fracture
Planning for management
Bony lesion around ankle

28. CT SCAN OF ANKLE

30. CT SCAN OF HAND
indications
-diagnosis of acute hand injuries- # dislocation of
carpal.
-diagnosis of initial degenerative changes.
-visualization of bone tumors.
-demonstration of distal radio-ulnar instability.
-demonstration of intra-articular loose bodies
-demonstration of pathological rotation in pronation-
supination following a DER #.
Post-operative follow up in scaphoid pseudoarthrosis

32. MRI IN ORTHOPAEDICS
Prof Peter Mansfield -2003

33. WE ARE MAGNETS! Really?
• Human body is built of only 26 elements.
• Let us ignore all elements but Hydrogen.
• When in ionic state (H+), it is nothing but a
proton.
• Proton is not only positively charged, but also
has magnetic spin (wobble)!
• MRI utilizes this magnetic spin property of
protons of hydrogen to elicit images!!
• We are magnets!

34. But why we can’t act like magnets?
• The protons in body
are spinning in a hap
hazard fashion, and
cancel all the
magnetism. That is our
natural state!
• We need to discipline
them first, how?

35. We need a big magnet from outside!
• Magnetic field strength:
0.3 – 7 T (2500 times more
than earth’s magnetic
field). Average field
strength – 1.5 T
• Open magnet – less field
strength, less
claustrophobic
• Closed magnet – more
field strength,
claustrophobic

36. Now, its time to listen to radio in
RESONANCE.
• Pushing a swing in time with natural
interval of the swing will make the
swing higher and higher.
• Similarly, radio frequency pulses in
resonance push the aligned protons (H+)
to a higher energy level.

37. What is Radio Frequency pulse?
• Same as Radio waves – high wavelength, low
energy electromagnetic waves
• Radiofrequency coils
– Act as transmitter and receiver
– Different types of coils

38. Turn off the radio
• The higher energy
gained by the protons
is retransmitted
(NMR signal)
• The original
magnetization begins
to recover (T1)
• The excessive spin
begins to dephase
(T2)

39. Now, we re-transmit the energy for
image processing
• The emitted energy is too small (despite
2500 times the magnetic field with
resonance RF pulse) to convert them
into images.
• Hence, repeated “ON-OFF” of RF pulses
are required.
• The emitted energy is stored (K-space),
analysed and converted into images.

41. MRI SHOULDER
Rotator cuff Instability Other
Bursitis Labral lesion Tumors
Intratendinous
degeneration
Capsule lesion Fractures
Partial tear RC Bony bankart defect Avascular necrosis
Complete tear RC Hill –Sachs defect Inflammation
Muscle fibrosis and
atrophy
Rotator cuff lesion
Arthritis

42. Axial image of shoulder

43. Axial image of shoulder

44. Axial image of shoulder

45. Axial image of shoulder

46. Coronal image of shoulder

47. Coronal image of shoulder

48. Coronal image of shoulder

49. Coronal image of shoulder

50. Sagital image of shoulder

51. Sagital image of shoulder

52. Sagital image of shoulder

55. MRI KNEE
Meniscal lesion
Cruciate ligament tears
Collateral ligament tears
Cartilage lesions: arthritis,osteochondritis dissecans
Inflammatory changes: Synovitis
Changes in bone: oedema, necrosis, fracture
Cysts : baker cyst
Tumors
Intra-articular loose bodies
Soft tissue envelope: tear ,hematoma, tumor.

56. • Sections
• Coronal- Ant. To Post.
• Sagital- Lateral to Medial
• Axial- From above downward
• Position for knee
MRI-
• Knee in full extension and 5
degree of
• internal rotation

57. Meniscal Tear
Grade 1- Globular signal
within the meniscus.
Grade 2- Linear signal
within the meniscus
not reaching the
articular surface.
Grade 3- Linear signal
within the meniscus
reaching the articular
surface.

58. GRADE-1 GRADE-2 GRADE-3

60. Radial tear- Tear perpendicular to free
edge of meniscus

61. Longitudinal tear

62. Bucket Handle Tear-
Longitudinal tear
along the length of the meniscus
and the inner rim flips into the
intercondylar notch while
remaining attached to the
anterior and posterior horns.
Double-PCL sign -The flipped
fragment lies inferior and
anterior to the PCL

64. Meniscal cyst
• Joint fluid is expressed
into adjacent soft tissue
through the tear
• Mostly occur in medial
compartment
• Most common
associated tear is
horizontal cleavage tear

65. ACL Tear
Acute-
 Replacement of normal striated
appearance by cloud like high
signal intensity .
 Discontinuity of ligament and
fibres don’t go parallel to
intercondylar roof
• Chronic-
 Nonvisualisation of ligament or
Angulation of ligament because
of scarring.
 Shallow orientation not parallel
to intercondylar roof

66. normal
acute
avulsion
chronic

67. PCL TEAR

68. Partial PCL tear Complete PCL tear PCL avulsion

69. Medial Collateral Ligament
Grade I : Edema &
hemorrhage superficial to
lig.
Grade II : Displacement of lig.
fibres from bone
Grade III : Complete lig.
discontinuity.

70. Grade I Grade II Grade III

71. Lateral Collateral Ligament tear

72. O”donoghues Triad
ACL TEAR MCL TEAR MM TEAR

73. ITB FRICTION QT RUPTURE JUMPERS KNEE

74. BAKERS CYST

75. Chondromalacia patella
NORMAL PATELLA

76. Grade -I Grade -II
Grade -III
Grade -IV

77. MRI SPINE

78. AXIAL IMAGE

80. SAGITAL IMAGE
Mid sagital parasagital Foraminal sagital

81. DISC DEGENERATION DISEASE

82. DISC BULGE

83. DISC HARNIATION

85. Spinal canal stenosis

87. Tubercular spine

88. MRI HIP
AVASCULAR NECROSIS OF FEMORAL HEAD
PERTHES DISEASE
SEPTIC ARTHRITIS
SOFT TISSUE INJURIES WITH FRACTURES
OSTEOARTHRITIS
OCCULT OSSEOUS INJURIES
TUMORS AROUND HIP
LABRAL AND CAPSULAR PATHOLOGY

89. Acetabular labral tear
1.Degenerative 2.femoro-acetabular impingement 3.traumatic
4.hypermobility 5.psoas impingement 6.dysplastic labral tear

90. Greater trochanteric pain syndrome

91. Osteonecrosis (AVN)

92. Before entering tunnel, there is
a checklist!
►No mobiles, no credit cards, please!
►Known potential safety concerns due
to large static magnetic field:
– Internal cardiac pacemakers
– Steel cerebral aneurysm clips
(ferromagnetic)
– Small steel slivers embedded in eye
– Life-support equipment with magnetic
steel
– Cochlear implants
– Stents anywhere in the body
– Needs sedation- infants, claustrophobia

93. MRI
►Faster
►Less expensive
►Less sensitive to patient
movements
►Easier in claustrophobics
►Acute haemorrhage
►Calcification
►Bone details
►Foreign body
►No ionising radiation
►Greater details, hence
more sensitive and more
specific
►Any plane scanning
►Contrast less allergic
►No beam hardening
artefact
CT

94. And the disadvantages?
• Claustrophobia. Patients are in a very
enclosed space.
• Weight and size. There are limitations to how
big a patient can be.
• Noise. The scanner is very noisy.
• Cost. A scanner is very, very expensive,
therefore scanning is also costly.
• Medical Contraindications. Pacemakers, metal
objects in body etc.