Development and evaluation of a numerical simulation approach to predict metal artifacts from passive implants in MRI

Tobias Spronk,Gregor Schaefers,Oliver Kraff,Harald H Quick,Jakob Kreutner

doi:10.1007/s10334-021-00966-5

Abstract

ObjectiveThis study presents the development and evaluation of a numerical approach to simulate artifacts of metallic implants in an MR environment that can be applied to improve the testing procedure for MR image artifacts in medical implants according to ASTM F2119.MethodsThe numerical approach is validated by comparing simulations and measurements of two metallic test objects made of titanium and stainless steel at three different field strengths (1.5T, 3T and 7T). The difference in artifact size and shape between the simulated and measured artifacts were evaluated. A trend analysis of the artifact sizes in relation to the field strength was performed.ResultsThe numerical simulation approach shows high similarity (between 75% and 84%) of simulated and measured artifact sizes of metallic implants. Simulated and measured artifact sizes in relation to the field strength resulted in a calculation guideline to determine and predict the artifact size at one field strength (e.g., 3T or 7T) based on a measurement that was obtained at another field strength only (e.g. 1.5T).ConclusionThis work presents a novel tool to improve the MR image artifact testing procedure of passive medical implants. With the help of this tool detailed artifact investigations can be performed, which would otherwise only be possible with substantial measurement effort on different MRI systems and field strengths.

Highlights

Due to the increasing number of Magnetic Resonance (MR) examinations and the growing percentage of patients with biomedical implants [1,2,3], it is becoming increasingly important to obtain a detailed understanding of the behavior of implanted medical devices (IMD) in an MR environment
Due to the clinical relevance of medical implants and the impact of their artifacts on MRI diagnostics, the ASTM F2119 standard has been formulated by the American Society for Testing and Materials (ASTM) defining procedures for measuring MR artifacts from medical implants [12]
If a patient with an implant is to be examined in an MRI system with different field strength, e.g. 3T or even 7T, the results of the artifact test obtained at only 1.5T may have no direct or only limited clinical relevance

Summary

Introduction

Due to the increasing number of Magnetic Resonance (MR) examinations and the growing percentage of patients with biomedical implants (e.g. stents, orthopedic implants) [1,2,3], it is becoming increasingly important to obtain a detailed understanding of the behavior of implanted medical devices (IMD) in an MR environment. Due to the clinical relevance of medical implants and the impact of their artifacts on MRI diagnostics, the ASTM F2119 standard has been formulated by the American Society for Testing and Materials (ASTM) defining procedures for measuring MR artifacts from medical implants [12]. This standard describes an experimental setup to determine the artifact size in MRI under strictly defined test parameters. The ASTM standard requires performing the testing procedure at only one field strength (1.5T or 3T) and only for a limited set of sequence parameters This may lead to a limited transferability of test results to all patient cases and potential MRI examinations. Based on the increasing relevance of MR scans at higher field strengths (3T and 7T) [13, 14], currently a potential challenge is that the artifact size of older implants has been evaluated at 1.5T only

Methods

Results

Discussion

Conclusion