MRPen – 3D Marker Tracking for Percutaneous Interventions

Introduction In percutanous MR-guided interventions passive markers are used to delineate the position or the trajectory of rigid instruments. In particular, for linear instruments such as puncture needles cylindrical markers are favorable, as the instrument can be safely accommodated in their interior. Cylindrical markers can be localized rapidly if their approximate position is known [1]; however, only the symmetry axis of the instrument is determined and the rotation angle against the axis, which can be important e.g. to avoid needle deflection, is not known. In this work, a modified passive marker is proposed. The 3D position and rotation of the marker is estimated in real time, and an imaging slice is adjusted and orientated accordingly. Through the integration of a rotation-invariant linear structure, additionally the marker rotation is detected in two steps using a dedicated phase-only cross correlation algorithm.