Tracking planar orientations of active MRI needles.

PURPOSE To determine and track the planar orientation of active interventional devices without using localizing RF microcoils. MATERIALS AND METHODS An image-based tracking method that determines a device's orientation using projection images was developed. An automated and a manual detection scheme were implemented. The method was demonstrated in an in vivo mesocaval puncture procedure in swine, which required accurate orientation of an active transvascular needle catheter. RESULTS The plane of the catheter was determined using two projection images. The scan plane was adjusted automatically to follow the catheter plane, and its orientation with respect to a previously acquired target plane was displayed. The algorithm facilitated navigation for a fast and accurate puncture. CONCLUSION Using image-based techniques, with no mechanical design changes, the orientation of an active intravascular probe could be tracked.