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. Author manuscript; available in PMC: 2016 May 1.
Published in final edited form as: Magn Reson Med. 2014 Jun 5;73(5):1803–1811. doi: 10.1002/mrm.25300

Figure 4.

Figure 4

One-dimensional MR-tracking signal-intensity profiles acquired with an active stylet filled catheter after insertion into the gel phantom, which contained 14 other conventional stylets. (a) Signal intensity profile from acquisition without applying an orthogonal dephasing gradient. In this case, the broad signal from the coupled surrounding stylets overwhelmed the peak from the micro-coil, resulting in the in-ability to obtain the true micro-coil location (the narrow peak highlighted with the black arrow). (b,c) Signal intensity profiles from acquisition with orthogonal PFD gradients applied in two different directions. Some PFD directions were superior in preserving the signal from the micro-coil while suppressing the broad surrounding signals. (d) Tracking signal, achieved by applying a maximum intensity projection to the intensity profiles generated from three different orthogonal dephasing gradients, provided a very high SNR to determine the micro-coil location.