Transcript CAS NUMéro 1

MRI OF PROTHETIC IMPLANTS IN MSK
Nathalie CHEMLA MD, Eric PESSIS MD,
Clinic Paris V
Cochin Hospital Paris
CCN Saint Denis
France
MRI OF PROTHETIC IMPLANTS IN MSK
• The use of MRI in the
presence of metallic
hardware has
traditionally been
limited by susceptibility
artifacts generated by
the presence of the
metallic components.
PULSE PARAMETERS MODIFICATIONS ON SE
– Maximize the
bandwidth
– Imaging at 1.5 T,
instead of 3 T
– Thin sections
– Large matrix
(encoding phase
perpendicular to
métal axis)
– High number of
excitations
STIR AND METAL ARTIFACTS
• Use STIR
imaging to
avoid failure
of fat
suppression
(instead of
frequencyselective fat
suppression
MAVRIC ( multiacquisition variableresonance image combination )
• However, these
factors can be not
sufficient.
• More recently,
new technique
such as
(MAVRIC) : a
method to correct
displacement
artifacts
STIR
MAVRIC
MAVRIC
•
•
•
•
3D Fast Spin Echo PD technic
With or without IR (fat sat effect)
multiple overlapping volumes .
Helps eliminate through-plane distortions
and reduce in-plane artifacts.
• The combined images have minimal
artifact and include signal from a wide
range of frequency offsets near metal.
MAVRIC
• Maximize bandwith
• FOV: minimum 18 cm to avoir aliasing
wrap-around
• Minimum 5 mm slices
• 110° angle to reduce SAR (specific
absorbtion rate)
• High matrix
TENDINITIS AND STRESS FRACTURE
CUBE VERSUS MAVRIC
Hip arthroplasty: osseous integration
• Using conventional SE T1 and STIR MR imaging technique,
the regions of bone around the metal implants are obscured
by artifacts (white arrows).
• MAVRIC image show improved clarity and help to visualize
bone-stem interface (yellow arrows)
T1
STIR
MAVRIC
Hip arthroplasty :osseous integration
• Complete osseous integration of a cementless
hip arthroplasty implant : direct contact between
the implant and the surrounding trabecular bone
without separation.
FSE T2 with fat
suppression
MAVRIC
TOTAL KNEE ARTHROPLASTY: OSTEOLYSIS
•
•
Periprosthetic osteolysis over the anterior aspect of tibial peg ( red arrow) well
visualized on plain film and
Not visible on FSE T2 with water excitation (IDEAL) MR image
FSE T2 IDEAL
Total knee arthroplasty: osteolysis
•
•
Periprosthetic osteolysis over the anterior aspect of tibial peg (red arrow) is well
visualized on T2 MAVRIC image and
Not visible on correspondant FSE T2 with water excitation (IDEAL) image
Sagittal T2 MAVRIC
FSE T2 IDEAL
Lumbar disk arthroplasty at the L4-L5 level
•
•
Conventional plain film and MR images of the lumbar spine (SE T1 and FSE T2
sequences) show severe artifacts from orthopedic hardware that obscure the
anatomy and limit evaluation of the spinal canal with MRI (yellow arrows).
Corresponding MAVRIC image show significant reduction of artifact in the spinal
canal (white arrow).
SE T1
FSE T2
T2 MAVRIC
•
•
Screw fixation of a sacroiliac joint disruption
Conventional MR images of the lumbar spine (SE T1 and FSE T2 sequences) show
severe artifacts from a screw that obscure the anatomy and limit evaluation of the
spinal canal with MRI (yellow arrows).
Corresponding MAVRIC image show significant reduction of artifact in the spinal canal
(white arrow).
FSE T2
SE T1
FSE T2
Screw fixation of a sacroiliac joint disruption
•
•
Conventional sagittal MR image of the lumbar spine (FSE T2 sequence)
shows severe artifacts from a screw that limit evaluation of the spinal canal
(yellow arrow).
Corresponding MAVRIC images shows significant reduction of artifact in the
spinal canal (white arrow).
FSE T2
T2 MAVRIC
T2 MAVRIC
SE and corresponding MAVRIC images show significant reduction of
artifact in the spinal canal especially on axial plan.
T2SE
Is there disk herniation ?
MAVRIC
Mavric: no disk hernation
CERVICAL SYRINX BETTER ANALYSIS WITH MAVRIC
Conclusion
•
Multiacquisition Variable-Resonance Image
Combination (MAVRIC) Method
 Allows to reduce substantially artifacts from metal
implants at MRI
 Improve visualization of metal-to-bone interface
 Improve the visualization of soft tissue near and far
the metallic implant
 Evaluation of metal implants and adjacent bone or
tissue is enhanced with MAVRIC images
THANKS TO DR ERIC PESSIS
THANKS TO ERIC LÉVÊQUE
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