MRI is an essential tool in the accurate diagnosis of musculoskeletal diseases. It provides detailed images of bones, joints, and soft tissues without exposing patients to radiation. The document discusses the fundamentals of how MRI works and key sequences such as T1-weighted and T2-weighted. It then examines the use of MRI in evaluating common orthopedic conditions affecting the spine, knee, hip, shoulder, wrist, foot and ankle. MRI is useful for assessing injuries, tumors, and other pathologies. It allows evaluation of the extent of issues like disc herniations, ligament tears, and fractures.

1. MRI in Orthopaedics
Presenter: Dr Raghavendra S
Moderator:Dr Sivaprasad
RRMCH,BANGALORE

2. Introduction
• MRI is an essential tool in the accurate diagnosis and
treatment of musculoskeletal disease.
• Basic working knowledge of certain key principles is
important for the accurate utilisation of the technology
• useful when the examination is directed at solving a
certain clinical problem, but its value as a screening study
for nonspecific pain is more limited.

3. Fundamentals of MRI
• All neutrons and protons within the nucleus
spin about their axes and generate a
magnetic field called a magnetic dipole.
• Even-numbered nuclei cancel each other
out.
• Odd-numbered nuclei generate a magnetic
moment, which can be represented as a
vector.

4. • When placed in a magnetic
field, odd-numbered nuclei
align parallel to the external
magnetic field in one of two
orientations: spin-up or spin-
down
• spin-up orientation (slightly
greater stability) and
generate an overall small
net magnetization vector

5. • human body is replete
with hydrogen, a
ubiquitous atom with
odd-numbered nuclei
(hydrogen has one
proton and no neutrons)
• precess, or “wobble

6. • When an RF pulse
is applied within an
external magnetic
field, the net
magnetization
vector flips from its
longitudinal
direction by a
certain angle (flip
angle).

7. • This flipping process
produces a
transverse
magnetization vec-tor
(perpendicular to the
external magnetic
field) and a
longitudinal
magnetization vector
(parallel to the
external magnetic
field)

8. • When an RF pulse is turned off , the precessing nuclei return
to their original equilibrium state and realign with the external
magnetic field.
• The return or recovery of the longitudinal magnetization is
known as T1 recovery(spin-lattice relaxation)
• the transverse magnetisation vector decays exponentially,
with a decay rate constant, or T2.(spin-spin relaxation)
• As would be expected, T1, T2, and differ for individual
tissues.

10. • T1-weighted image
• T2-weighted image
• Intermediate-weighted or proton-density–weighted image
• Fluid-sensitive sequence, such as STIR or fat-suppressed T2-weighted image
• Gradient-echo image
• Postgadolinium T1-weighted image

11. CONTRAINDICATIONS
• Absolute
• intracerebral aneurysm clips
• automatic defibrillators
• internal hearing aids and metallic orbital foreign bodies.
• cardiac pacemakers are not MRI safe.MRI- compatible pacemakers has been recently developed.
• Cardiac valve prostheses can be safely scanned.
• Relative
• first-trimester pregnancy
• intravascular stents placed within 6 weeks.
• metal external fixation devices should not be scanned
• internal orthopaedic hardware and orthopaedic prostheses are safe to scan.
• titanium prostheses generate much less artifact than stainless steel.

12. General Spine Anatomy
• discovertebral complex has three components:
• Cartilaginous end plate
• Annulus fibrosus
• Nucleus pulposus
• intervertebral discs show intermediate signal intensity on
T1-weighted images and high signal intensity on T2-
weighted images.The outer annulus appears hypointense
on T2.

13. • As the disc degenerates and as patients age, the signal intensity of the
nucleus pulposus decreases.
• CSF
• Spinal Cord
• Ligaments
• The ligamentum flavum connects the lamina of adjacent vertebrae and is
seen as a hypointense band posterior to the dura.
• nerve roots have intermediate signal intensity and are surrounded by high
signal intensity fat on T1-weighted images and by high signal intensity
CSF on T2-weighted images..

16. Lumbar Spine
• Sagittal Images
• The midsagittal
image should be
evaluated
first,then
sequentially
evaluated toward
each side to
assess the facet
joints and neural
foramina.
• sagittal images
can be
concurrently
evaluated with
the axial
sequence to
confirm laterality.

18. AXIAL IMAGES
• the degree of
contribution of
the three
primary
contributors to
spinal stenosis
(disc pathology,
facet
arthropathy, and
ligamentum
flavum
hypertrophy)
should be noted

20. Nomenclature and Classification of
Lumbar Disc Pathology
• Fardon and Milette
• Normal: a young disc that is morphologically normal
• Congenital/developmental variant
• Degenerative/traumatic lesion:lesion: annular tear, degenera-
tion, herniation
• Inflammation/infection
• Neoplasia
• Morphologic variant of unknown importance

21. • annular tears ( annular
fissures) are separations
between annular fibers,
avulsion of fibers from their
vertebral body insertions.
• degenerative- includes
desiccation, fibrosis,
narrowing of the disc space,
diffuse bulging of the
annulus beyond disc space,
extensive fissuring, defects
and sclerosis of the end
plates, and osteophytes.

22. • Herniation is defined
as a localized
displacement of disc
contents beyond the
borders of the
intervertebral disc
space
• disc material may
include
• nucleus
• cartilage
• fragmented
apophyseal bone
• annular tissue or a
combination

23. • PROTRUSION and EXTRUSION

25. Lumbar disc protrusion. Sagittal (A) and axial (B) T2-weighted images showing a
central disc protrusion at the L4-L5 level (arrow
on each).

26. EXTRUSION

31. Lumbar Spinal Stenosis
• compress
ion of the
neural
elements
in the
spinal
canal,
lateral
recesses,
or neural
foramina.

32. • Mild-canal
triangular ,flavum
< 2mm,thecal sac
not compressed.
AP >75%
• Moderate-mild +
deformity of the
cal sac AP canal
diameter 50 to
75%
• Severe-
pronounced
deformity of
sac,flavum>4mm,
AP <50

33. KNEE

35. ACL
• Course
• Composed of the antero-
medial and posterolateral
bundles.
• Intraarticular but
extrasynovial
• Should not show marked
increased signal on T2-
weighted imaging, but it may
have minimally increased
signal on T1-weighted
images because of the
presence of fatty tissue

37. PCL
• PCL curves
anteriorly to
insert on the
anterolateral
aspect of the
medial femoral
condyle
• appears as a
thicker, darker,
curved band
compared with
the ACL.

38. KNEE
PATHOLOGIC CONDITIONS OF MENISCI
• composed-fibrocartilage
appear as low-signal
structures on all
sequences
• sagittal images, the
menisci appear as dark
triangles in the central
portion of the joint and
assume a “bow tie”
configuration at the
periphery of the joint

39. Meniscal Tears

40. • Most tears
involve the
medial
meniscus,
but most
acute tears
involve the
lateral
meniscus
• chronic ACL
tears
associated
with
meniscus
tears.
posterior horn of the
medial meniscus

41. Bucket handle tear

42. medial meniscus and
displaced inferior to the PCL
(arrow-
head), exhibiting the double-
PCL sign

43. ACL TEARS
• H/o twisting or
valgus injury to the
knee with a planted
foot and often
describes sensing
a “pop” inside the
knee.
• adult ACL usually
avulses from its
femoral attachment
or develops an
intrasubstance
tear.
• The tendon does
not have to
dissociate
completely to
become
incompetent.
In skeletally immature patients,
the ACL may remain intact and avulse a fragment of
bone off of the attachment.

45. • MRI findings
commonly
associated with
acute ACL
injury include
loss of ligament
continuity and
replacement of
the ligament by
a poorly
marginated
pseudomass -
shows high
signal on T2
and low signal
on T1.

46. a bone bruise- lateral femoral condyle and the posterior aspect of the
lateral tibial platea

47. • sagittal fat-suppressed proton-density
image shows advanced degeneration
(marked thickening) of the ACL
Segond fracture

48. PCL
consistently has
lower signal on
MRI than does the
ACL. MRI is very
sensitive for tears
of the PCL
because of its
normal low signal
Any increased
signal within the
PCL on T2-
weighted images
is suspicious for
injury.

50. HIP
• initial radiographs are often
normal, MRI may confirm the
diagnosis.
• better delineates the extent of
marrow necrosis.
• On T1-weighted images, the
classic MRI appearance of
osteonecrosis is that of a
geographic region of abnormal
marrow signal within the normally
bright fat of the femoral head.
• The T2-weighted images reveal a
margin of bright signal, and the
resulting appearance has been
termed the “double line” sign. This
sign essentially is diagnostic of
osteonecrosis.
OSTEONECROSIS

51. Fig. 7.10 A coronal FSE image of the
left hip showing a region of os-
teonecrosis at the weight-bearing
surface of the femoral head with
a classic serpentine line of
demarcation from the adjacent normal
bone

52. Osteoarthritis
• characterized by articular cartilage degenerative change with hip joint space narrowing
Femoroacetabular impingement
Previous slipped capital femoral epiphysis
Developmental dysplasia of the hip
Legg-Calvé-Perthes disease
Trauma
Other anatomic variants
• appearance of osteoarthritis on MR images is similar to that on conventional radiographs
Hypointense subchondral sclerosis of the femoral head and acetabulum
Joint space narrowing
Osteophyte formation
Subchondral cysts

54. SHOULDE
R
• tendons of the
supraspinatus,
infraspinatus, and
teres minor
muscles maintain
low signal
• Rotator cuff tears
appear as areas
of increased T2-
weighted signal,
representing fluid
within the tendon
substance
rotator cuff tear
impingement
rotator cuff tear

55. Impingement syndromes
• Although
impingement can be
suggested by an
imaging technique,
it remains a clinical
diagnosis
• narrowing of the
subacromial space
by spurs or
osteophytes, a
curved or hooked
acromial morpholgy,
and signal
abnormalities in the
cuff indicating
tendinosis or
tendinopathy.
Type I acromion

56. Rotator Cuff Tears
• The supraspinatus and
infraspinatus tendons are the most
common tendons torn.
• Rotator cuff tears can be
characterized as partial thickness
or full thickness
• partial-thickness tears
• increased signal in the rotator cuff
that only partially traverses the
rotator cuff substance.
A sagittal oblique T2-weighted
image showing a partial-
thickness rotator cuff tear
(arrow) on a background of
tendinosis

57. Full-thickness tears of the subscapularis
and
teres minor
• Low to intermediate signal intensity on
T1-weighted images, intermediate to
high signal intensity on proton-density
images, and fl uid signal intensity on
T2-weighted sequences
complete tendon defect or complete
discontinuity of the tendon with retraction, and
abnormal
increased signal intensity within the tendon
defect
A sagittal oblique T2-weighted image showing
a full-thick-
ness rotator cuff tear

59. Type II acromion.
Type III acromion

60. TUMOR
• Defining tumor extent and planning for surgical and
radiation therapy.
• T1-weighted images are useful in identifying areas of
marrow replacement of edema.
• T2-weighted sequences delineate soft-tissue exten-sion
because most neoplasms become hyperintense in
contrast to surrounding muscle and fat.

61. coma arising in osteochondroma. A, Radiograph reveals irregular ossification throughout e
ighted coronal image shows hypointense marrow signal within lesion and extension of this
ur (arrows). C, Axial fat-suppressed, T2-weighted image demonstrates typical hyperintensi
(arrows), in contrast to surrounding normal tissues

62. Osteochondroma
• the most common benign
bone tumor
• MRI can be used to
assess the malignant
transformation of an
osteochondroma to a
chondrosarcoma. If the
cartilage cap exceeds 2
cm in adults and 3 cm in
chil-dren, malignant
transformation is
considered to be more
likely.

63. Aneurysmal Bone Cyst
• Conventional
radiographs show an
expansile, lytic lesion
that expands the cortex
into the surrounding
soft tissues. MRI
shows a rim of low
signal intensity, with
multiple lobules and
septations
• MRI shows a rim of low
signal intensity, with
multiple lobules and
septations
A coronal T2-weighted image of the distal femur
shows
an aneurysmal bone cyst with multiple fl uid–fl uid
levels (arrows). The
lesion is expansile, destroying the cortex

64. WRIST
Early osteonecrosis of scaphoid following fracture. A, T1-weighted coronal image of
the wrist shows a transverse
fracture of the mid-scaphoid (arrow). B, Fat-suppressed T2-weighted coronal image
reveals marrow edema in the distal pole fragment
only (arrow), suggesting proximal pole ischemia.

65. FOOT AND ANKLE
• Most common conditions
• tendinopathy, articular disorders, and osseous pathologic
conditions, often after trauma.
• TENDON INJURIES
• Most commonly affected are the calcaneal and posterior
tibial tendons

66. • The pathologically enlarged
tendon-low signal on all
sequences.
• When partially torn, the tendon
demonstrates focal or fusiform
thickening with edema or
hemorrhage in T2.
• With complete rupture, there is
discontinuity of the tendon fibers.
• Increased fluid in the sheath of the
tendon-indicates tenosynovitis
• Insufficient or ruptured tendons can
appear thickened, attenuated, or
even discontinuous.

67. OSSEOUS INJURIES
• Heel pain
• Differentiating stress fracture and
plantar fasciitis

68. Osteochondritis dissecans of talus

69. • Morton neuroma is most frequently
• found in the distal third metatarsal interspace
• Unlike most other tumors, this lesion lacks increased signal
on T2-weighted sequences.
• common foot mass, plantar fibroma or
• plantar fibromatosis, usually is quite easily confirmed by the
• presence of signal-poor mass arising from the plantar fascia

70. Metal Artifact Reduction Sequence
MARS
• Artifact arising from metal hardware remains a significant
problem in orthopedic magnetic resonance imaging
• The sequence, which is based on view angle tilting in
combination with increased gradient strength, can be
conveniently used in conjunction with any spin-echo sequence
• allows visualization of marrow adjacent to hip screws, thus
enabling diagnosis or exclusion of avascular necrosis.
• spinal fixation hardware, the MARS technique frequently allows
visualization of the vertebral bodies and spinal canal contents
• visualization of structures adjacent to implanted
metal staples,pins, or screws

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73. • Thank you