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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 Bibliography 1. Fritz J, Lurie B, Miller TT, Potter HG. MR imaging of hip arthroplasty implants. Radiographics : a review publication of the Radiological Society of North America, Inc. 2014;34(4):E106-32. 2. Hargreaves BA, Worters PW, Pauly KB, Pauly JM, Koch KM, Gold GE. Metal-induced artifacts in MRI. AJR American journal of roentgenology. 2011;197(3):547-55. 3. Hayter CL, Koff MF, Shah P, Koch KM, Miller TT, Potter HG. MRI after arthroplasty: comparison of MAVRIC and conventional fast spin-echo techniques. AJR American journal of roentgenology. 2011;197(3):W405-11. 4. Koff MF, Shah P, Koch KM, Potter HG. Quantifying image distortion of orthopedic materials in magnetic resonance imaging. Journal of magnetic resonance imaging : JMRI. 2013;38(3):610-8. 5. Nawabi DH, Hayter CL, Su EP, et al. Magnetic resonance imaging findings in symptomatic versus asymptomatic subjects following metal-onmetal hip resurfacing arthroplasty. The Journal of bone and joint surgery American volume. 2013;95(10):895-902.