In vitro assessment of a fiducial marker for lung lesions: MRI issues at 3 T

Abstract

Objective: The objective of our study was to assess MRI issues at 3 T for a newly developed fiducial marker used to localize lung lesions.

Materials and methods: A fiducial marker designed for lung lesions (super-Lock Cobra) was investigated at 3 T for magnetic field interactions, MRI-related heating, and artifacts using standardized techniques. Magnetic field interactions were assessed with regard to translational attraction and torque. MRI-related heating was characterized by placing the marker in a gelled-saline-filled head-torso phantom and performing MRI using a transmit-receive radiofrequency body coil at an MR system-reported, whole-body-averaged specific absorption rate of 2.9 W/kg for 15 minutes. Artifacts were measured for the marker on MR images obtained using T1-weighted spin-echo and gradient-echo pulse sequences.

Results: The fiducial marker displayed very low magnetic field interactions (2° deflection angle and no torque) at 3 T. MRI-related heating was at the same level as the "background" (i.e., phantom heating without the marker) temperature rise. Artifacts were relatively small in relation to the size and shape of the marker.

Conclusion: The results of this investigation show that there are no MRI-related safety concerns and, thus, that it would be acceptable (i.e., "MR conditional") for a patient with this new fiducial marker to be examined using MRI at 3 T or less. Artifacts, although relatively small, may create issues if the area of interest is the same as that of the marker or if the interpreting radiologist does not know the marker is present.