In the current project we are working with electromagnetic (EM) sensors for navigating medical instruments. The accuracy in experiments with phantoms reported in literature is around 1-2mm.
However, when EM tracking is used in the clinics, the accuracy is decreasing due to patient movement, breathing, pulsation, ... . Clinical studies with EM tracking systems in literature report higher tracking errors. Moreover, using an EM tracking system changes the workflow and the physician have to get used to it.
Therefore, I am interested in whether EM tracking systems are currently used in clinical routine. If this is the case, what is the experience of physicians using such a system?
Article Electromagnetic Tracking in Medicine-A Review of Technology,...
Well, this is one of the first papers I red about EM tracking. It offers a good overview of this topic. Many clinical studies with EM tracking systems are cited in this paper. However, in the last section of the paper the authors conclude: While several clinical EM tracked systems have emerged, so far none has reached wide clinical use.
However, this paper was published in 2014. Six years in which these things may have changed. Moreover, my question is more related to whether EM Tracking is widely used or even has already become standard navigation in any medical procedure.
For example, I heard about Biomedical Centerline (https://www.centerlinebiomedical.com/), which develops and commercialize an endovascular guidance system based on EM tracking. However, the system is not yet available.
Hi Sonja,
I joined the department of movement science in NTNU three years ago. The team I joined, conducted research on the neck stability and they used EM tracking systems (EMTS) in their experiments (they used Liberty system from Polhemus). They wrote a paper on that experiment. Their results were questioned by the reviewers mainly due to the lack of accuracy when such systems are used for that type of experiments. My main task was analyzing the error of the EMTS. We wrote a paper on that, and the paper is still in the review process, but the conclusion could be useful.
Most of the papers that discuss this topic focus on the metal and EM interference and their effect on the position and orientation solutions (6 DOF). However, we discovered that the manufacturers of EMTS use linearization to approximate the measurements from the sensors (at least this is the case with Polhemus). I also discovered that this linearization induce a significant error in the position and orientation solution. This error, as you can imagine, increases with the movement of the sensor, whether in position or orientation. I couldn't find any work that addresses the problem of linearization as a source of error beside the EM interference.
To answer your question, I say the following. Generally speaking, the accuracy of the EMTS is questionable and this fact was realized by the researchers long time ago. However, since the EMTS have the excellent feature that they don't require a direct line of sight, they are still widely used in clinical experiments, as long as the motion to be detected is not very fast. Unfortunately, I can't give exact cut-off speeds beyond which the error will be unacceptable, but the paper under revision discusses those limits.
Thanks for your information. I look forward to the publication of your paper.
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