Wei Wang1,
2, Zion Tse3, Ravi T. Seethamraju4, Charles L.
Dumoulin5, Tina Kapur1, Akila N. Viswanathan2,
Robert A. Cormack2, Ehud J. Schmidt1
1Radiology,
Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United
States; 2Radiation Oncology, Brigham and Women's Hospital, Harvard
Medical School, Boston, MA, United States; 3Engineering,
University of Georgia, Athens, GA, United States; 4MR R&D, Siemens
Healthcare, Boston, MA, United States; 5Radiology, Cincinnati
Children's Hospital, Cincinnati, OH, United States
The presence of metal in MR-guided interventional procedures affects MR-tracking quality by causing static magnetic field and radiofrequency field inhomogeneities. A custom-built carbon fiber catheter for radiation bracytherapy applications was tested using different MR-tracking methods (zero-phase reference and Hadamard multiplexing schemes without or with phase-filed dithering (PFD) strategy). The test environment included surrounding metallic needles and simulated physiological motions from a motional platform. Results showed an MR-tracking capability at 40 fps and 0.6 &[mult] 0.6 &[mult] 0.6 mm3 and demonstrated that the Hadamard scheme produced a more accurate and robust result than zero-phase-reference, and the use of PFD dramatically enhanced both tracking schemes.