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Interaction of artificial metallic objects with biosusceptometric measurements
R Engelhardt1, E B Fung, P Kelly
1University Hospital Hamburg-Eppendorf, Germany. engelhar@uke.uni-hamburg.de
Neurology & Clinical Neurophysiology : NCN
|July 14, 2005
Summary
Metallic medical implants like port-a-caths and surgical clips generally do not interfere with liver iron concentration (LIC) measurements using biosusceptometry. However, dental braces can cause significant artifacts, especially in iron-overloaded patients.
Area of Science:
- Biomagnetism
- Medical Physics
- Materials Science
Background:
- Metallic objects in patients can distort magnetic fields used in medical imaging and biosusceptometry, leading to measurement artifacts.
- Accurate assessment of magnetic susceptibility and relaxation rates is crucial for diagnostic accuracy.
Purpose of the Study:
- To quantify the magnetic susceptibility of common medical implants (port-a-caths, surgical clips) and assess their impact on liver iron concentration (LIC) measurements.
- To evaluate the in vivo effect of port-a-caths and dental braces on LIC measurements using SQUID biosusceptometry.
Main Methods:
- SQUID biosusceptometry was used to measure the magnetic susceptibility of vascular access port-a-caths and surgical clips.
- In vivo measurements assessed the impact of port-a-caths and dental braces on LIC measurements at varying radial distances from the gradiometer.
Main Results:
- Port-a-caths exhibited a mean magnetic volume susceptibility comparable to non-ferromagnetic materials, with minimal impact on LIC at 5 cm.
- Modern surgical clips showed negligible interference with LIC measurements.
- Dental braces, particularly those with high Nickel content, demonstrated ferromagnetic properties and significantly interfered with LIC measurements, even in iron-overloaded livers.
Conclusions:
- Vascular access port-a-caths and modern surgical clips are generally safe for use with SQUID-based LIC measurements.
- Dental braces pose a significant artifact risk for LIC measurements due to their ferromagnetic properties and can obscure results in patients with high liver iron levels.