MRI compatibility and visibility assessment of implantable medical devices

Schueler, Beth A.; Parrish, Todd B.; Lin, Jyh Cherng; Hammer, Bruce E.; Pangrle, B. J.; Ritenour, E. Russell; Kucharczyk, John; Truwit, Charles L.

doi:10.1002/(sici)1522-2586(199904)9:4<596::aid-jmri14>3.0.co;2-t

Cited by 73 publications

(49 citation statements)

References 17 publications

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“…According to the above-mentioned standard, magnetically induced torque has to be smaller than the product of the maximum device length and device weight, i.e., the mechanical torque T me due to gravity. Several medical products as surgical instruments or prosthetic heart valves have been examined for hazardous torque in the MR environment applying at least the limits in this standard (3)(4)(5)(6)(7)(8)(9)(10)(11)(12).…”

mentioning

confidence: 99%

Eddy‐current induction in extended metallic parts as a source of considerable torsional moment

Graf

Lauer

Schick

2006

Magnetic Resonance Imaging

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Purpose:To examine eddy-current-provoked torque on conductive parts due to current induction from movement through the fringe field of the MR scanner and from gradient switching. Materials and Methods:For both cases, torque was calculated for frames of copper, aluminum, and titanium, inclined to 45°to B 0 (maximum torque case). Conditions were analyzed in which torque from gravity (legal limit, ASTM F2213-02) was exceeded. Experiments were carried out on a 1.5 T and a 3 T scanner for copper and titanium frames and plates (Ϸ50 ϫ 50 mm 2 ). Movement-induced torque was measured at patient table velocity (20 cm/second). Alternating torque from gradient switching was investigated by holding the specimens in different locations in the scanner while executing sequences that exploited the gradient capabilities (40 mT/m). Results:The calculations predicted that movement-induced torque could exceed torque from gravity (depending on the part size, electric resistance, and velocity). Two experiments on moving conductive frames in the fringe fields of the scanners confirmed the calculations. For maximum torque case parameters, gradient-switching-induced torque was calculated to be nearly 100 times greater than the movement-induced torque. Well-conducting metal parts located off center vibrated significantly due to impulse-like fast alternating torque characteristics. Conclusion:Torque on metal parts from movement in the fringe field is weak under standard conditions, but for larger parts the acceptable limit can be reached with a high static field and increased velocity. Vibrations due to gradient switching were confirmed and may explain the sensations occasionally reported by patients with implants.

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confidence: 99%

Eddy‐current induction in extended metallic parts as a source of considerable torsional moment

Graf

Lauer

Schick

2006

Magnetic Resonance Imaging

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“…Previously performed numerical studies have only focused on the evaluation of the amount of RF energy absorbed by the tissues around different implants (SAR), but not on the device electronics. Schueler et al [2] calculated the magnetic field around an aluminum spheroid implant as well as the eddy currents on this implant surface. Field distribution around this spheroid implant was similar to the results obtained in the present work, but the RF field magnitude was not specified.…”

Section: Discussionmentioning

confidence: 99%

“…It is relatively easy, for example, to demonstrate that heating or induced voltages can occur, but far more difficult to prove that they are not hazardous. Experimental studies have been extensively used to assess the MRI-safety of various active implants (pacemakers [4]- [9], defibrillators [1], [5], neurostimulators [10], [11], and infusion pumps [2], [12], [13]) and this type of investigation is mandatory before the commercialization and marketing of implants as MRI safe. However, experimental tests are only possible at the end of the product development cycle when fully functional implants are available and design change costs are the highest.…”

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confidence: 99%

Safety of Active Implantable Devices During MRI Examinations: A Finite Element Analysis of an Implantable Pump

Büchler

Simon²,

Burger³

et al. 2007

IEEE Trans. Biomed. Eng.

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Abstract-The goal of this study was to propose a general numerical analysis methodology to evaluate the magnetic resonance imaging (MRI)-safety of active implants. Numerical models based on the finite element (FE) technique were used to estimate if the normal operation of an active device was altered during MRI imaging. An active implanted pump was chosen to illustrate the method. A set of controlled experiments were proposed and performed to validate the numerical model. The calculated induced voltages in the important electronic components of the device showed dependence with the MRI field strength. For the MRI radiofrequency fields, significant induced voltages of up to 20 V were calculated for a 0.3T field-strength MRI. For the 1.5 and 3.0T MRIs, the calculated voltages were insignificant. On the other hand, induced voltages up to 11 V were calculated in the critical electronic components for the 3.0T MRI due to the gradient fields. Values obtained in this work reflect to the worst case situation which is virtually impossible to achieve in normal scanning situations. Since the calculated voltages may be removed by appropriate protection circuits, no critical problems affecting the normal operation of the pump were identified. This study showed that the proposed methodology helps the identification of the possible incompatibilities between active implants and MR imaging, and can be used to aid the design of critical electronic systems to ensure MRI-safety.Index Terms-Biomedical equipment safety, finite element methods, magnetic resonance imaging.

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“…The stent-graft was suspended by a fine string, attached at the estimated center of mass, to a specially constructed device (a plastic protractor mounted on a wooden stand) and placed at the portal of the magnet bore (15)(16)(17)24,26). The accuracy of this device is Ϯ0.5°.…”

Section: Assessment Of Ferromagnetismmentioning

confidence: 99%

“…Previous studies have shown that MRI is safe if the metallic implant exhibits none, or negligible, ferromagnetism, in the sense that the metallic implant is not affected by the static magnetic field (15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25). With respect to heating, patients may safely undergo MRI if the metallic implant is not or is only slightly (Յ1.0°C) heated when tested ex vivo (16,(22)(23)(24)(25)(26)(27)(28)(29).…”

mentioning

confidence: 99%

MR Evaluation Ex Vivo and In Vivo of a Covered Stent-Graft for Abdominal Aortic Aneurysms: Ferromagnetism, Heating, Artifacts, and Velocity Mapping

Engellau

Olsrud

Brockstedt

et al. 2000

J. Magn. Reson. Imaging

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MRI compatibility and visibility assessment of implantable medical devices

Cited by 73 publications

References 17 publications

Eddy‐current induction in extended metallic parts as a source of considerable torsional moment

Eddy‐current induction in extended metallic parts as a source of considerable torsional moment

Safety of Active Implantable Devices During MRI Examinations: A Finite Element Analysis of an Implantable Pump

MR Evaluation Ex Vivo and In Vivo of a Covered Stent-Graft for Abdominal Aortic Aneurysms: Ferromagnetism, Heating, Artifacts, and Velocity Mapping

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