Verification of neuronavigated TMS accuracy using structured-light 3D scans

Noora Matilainen*, Juhani Kataja, Ilkka Laakso

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

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Objective. To investigate the reliability and accuracy of the manual three-point co-registration in neuronavigated transcranial magnetic stimulation (TMS). The effect of the error in landmark pointing on the coil placement and on the induced electric and magnetic fields was examined. Approach. The position of the TMS coil on the head was recorded by the neuronavigation system and by 3D scanning for ten healthy participants. The differences in the coil locations and orientations and the theoretical error values for electric and magnetic fields between the neuronavigated and 3D scanned coil positions were calculated. In addition, the sensitivity of the coil location on landmark accuracy was calculated. Main results. The measured distances between the neuronavigated and 3D scanned coil locations were on average 10.2 mm, ranging from 3.1 to 18.7 mm. The error in angles were on average from two to three degrees. The coil misplacement caused on average a 29% relative error in the electric field with a range from 9% to 51%. In the magnetic field, the same error was on average 33%, ranging from 10% to 58%. The misplacement of landmark points could cause a 1.8-fold error for the coil location. Significance. TMS neuronavigation with three landmark points can cause a significant error in the coil position, hampering research using highly accurate electric field calculations. Including 3D scanning to the process provides an efficient method to achieve a more accurate coil position.

Original languageEnglish
Article number085004
Number of pages12
JournalPhysics in Medicine and Biology
Issue number8
Publication statusPublished - 21 Apr 2024
MoE publication typeA1 Journal article-refereed


  • dosimetric modelling
  • electric field
  • landmark pointing
  • navigated TMS
  • navigation accuracy
  • transcranial magnetic stimulation


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