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Musculoskeletal Imaging

E3156. MRI of Ankle Arthroplasty Implants

Thawait G,  Netto C,  Schon L,  Fritz J. Johns Hopkins University, Baltimore, MD

Address correspondence to G. Thawait (gthawai1@jhmi.edu)

Background Information: Metal artifact reduction MRI of the ankle allows for comprehensive imaging evaluation of pain and dysfunction after arthroplasty, including periprosthetic bone resorption and osteolysis, synovitis, infection, periprosthetic fractures, arthrofibrosis, and component malalignment. The aim of this exhibit is to show the appearance of normal ankle arthroplasties and common abnormalities using optimal imaging parameters, including newer multispectral MR techniques.

Educational Goals/Teaching Points: The goal of this exhibit is to apply basic optimization and advanced techniques for metal artifact reduction MRI of ankle arthroplasty implants including multiacquisition with variable resonance image combination (MAVRIC) and slice encoding for metal artifact correction (SEMAC) algorithms. We will review the different FDA-approved ankle arthroplasty implants and their normal MRI appearances. Participants will be able to understand and diagnose the modes of failure of ankle arthroplasty implants using MRI and utilize a systematic checklist for structured reporting.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques: The following key pathophysiologic issues will be discussed with imaging findings: normal MRI appearances and MRI diagnosis of complications, including implant integration (biological and cement fixation, fibrous membrane formation, bone resorption, and osteolysis), bone lesions (progressive osteoporosis, implant subsidence, osseous stress reaction and focal overload, fracture, and osteonecrosis), synovitis (nonspecific synovitis, wear-induced synovitis, infection, and arthrofibrosis), impingement syndromes, sagittal implant alignment, musculotendinous abnormalities, and neurovascular compromise. We will also discuss appropriate imaging techniques including optimization strategies for MRI of ankle arthroplasty implants, multiparametric metal artifact MRI protocols (including dynamic and delayed contrast enhancement using conventional fast-spin-echo), MAVRIC and SEMAC pulse sequences, and types and frequency of modes of failure of ankle arthroplasty.

Conclusion: Ankle arthroplasties can be evaluated using metal artifact reduction MRI by optimizing the imaging protocol. Newer imaging sequences can provide optimal diagnostic value with shorter acquisition time and better metal artifact reduction using commercially available MR scanners. These imaging characteristics and scan techniques can provide optimal diagnostic value for patients with ankle arthroplasties to improve patient care.