Simultaneous 3D localization of multiple MR-visible markers in fully reconstructed MR images: proof-of-concept for subsecond position tracking

作者：Thoermer Gregor; Garnov Nikita; Moche Michael; Haase Juergen; Kahn Thomas; Busse Harald^*

来源：Magnetic Resonance Imaging, 2012, 20(3): 371-381.

DOI：10.1016/j.mri.2011.10.006

• MR markers
• Localization
• Guidance
• Navigation
• Tracking
• Interventional MRI

Purpose: To determine whether a greatly reduced spatial resolution of fully reconstructed projection MR images can be used for the simultaneous 3D localization of multiple MR-visible markers and to assess the feasibility of a subsecond position tracking for clinical purposes. %26lt;br%26gt;Materials and Methods: Miniature, inductively coupled RF coils were imaged in three orthogonal planes with a balanced steady-state free precession (SSFP) sequence and automatically localized using a two-dimensional template fitting and a subsequent three-dimensional (3D) matching of the coordinates. Precision, accuracy, speed and robustness of 3D localization were assessed for decreasing in-plane resolutions (0.6-4.7 mm). The feasibility of marker tracking was evaluated at the lowest resolution by following a robotically driven needle on a complex 3D trajectory. %26lt;br%26gt;Results: Average 3D precision and accuracy, sensitivity and specificity of localization ranged between 0.1 and 0.4 mm, 0.5 and 1.0 mm, 100% and 95%, and 100% and 96%, respectively. At the lowest resolution, imaging and localization took approximate to 350 ms and provided an accuracy of approximate to 1.0 mm. In the tracking experiment, the needle was clearly depicted on the oblique scan planes defined by the markers. %26lt;br%26gt;Conclusion: Image-based marker localization at a greatly reduced spatial resolution is considered a feasible approach to monitor reference points or rigid instruments at subsecond update rates.

• 出版日期2012-4