(Tuesday, 7/16/2019) 3:45 PM - 4:15 PM
Room: Exhibit Hall | Forum 8
Purpose: Paramagnetic fiducials are currently being investigated for use as surgical markers. Since the fiducial is delivered via a needle and detected with a portable detector the risk of displacement is lower than traditional wire localization. In this way, paramagnetic fiducials are similar to radioactive seed localization but without the use of radioactive material. There may be a need for additional imaging between implantation and surgery including MRI. In this work, we evaluated the severity of MRI artifacts resulting from a magnetic fiducial as well as methods to mitigate them.
Methods: A 5x1 mm paramagnetic seed (MagSeed Endomag) was implanted into the center of a pork shoulder phantom. Scanning was performed on both a 1.5 T and 3T scanner (450w and 750w, General Electric) using clinical 2D T1 weighted fast-spin-echo imaging and 3D metal artifact reduction (MAVERIC SL) sequences.
Results: The implantation of the paramagnetic fiducial resulted in a signal void of approximately 20 to 40 mm as well as off slice excitation resulting in signal hyperintensities along the slice direction. The metal artifact reduction technique was able to reduce the size of the signal void by 30% – 37% as well as eliminate any off slice excitation artifacts.
Conclusion: This work shows that MRI with a paramagnetic fiducial results in significant signal void around the marker. While metal artifact reduction techniques provide some reduction in the signal void, the void is still significant. Additional imaging concerns would include the success of more advanced MRI sequences such as fat saturation, Dixon techniques, etc. These results should be considered when risk-reward is evaluated before ordering MRI imaging near such a paramagnetic fiducial. If the area of clinical interest is expected to be near the fiducial than sequence choices will likely be limited and the resulting images might provide little useful information.
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