title: Prospective motion correction using tracking coils.
abstract: Intracavity imaging coils provide higher signal-to-noise than surface coils and have the potential to provide higher spatial resolution in shorter acquisition times. However, images from these coils suffer from physiologically induced motion artifacts, as both the anatomy and the coils move during image acquisition. We developed prospective motion-correction techniques for intracavity imaging using an array of tracking coils. The system had <50 ms latency between tracking and imaging, so that the images from the intracavity coil were acquired in a frame of reference defined by the tracking array rather than by the system's gradient coils. Two-dimensional gradient-recalled and three-dimensional electrocardiogram-gated inversion-recovery-fast-gradient-echo sequences were tested with prospective motion correction using ex vivo hearts placed on a moving platform simulating both respiratory and cardiac motion. Human abdominal tests were subsequently conducted. The tracking array provided a positional accuracy of 0.7 ± 0.5 mm, 0.6 ± 0.4 mm, and 0.1 ± 0.1 mm along the X, Y, and Z directions at a rate of 20 frames-per-second. The ex vivo and human experiments showed significant image quality improvements for both in-plane and through-plane motion correction, which although not performed in intracavity imaging, demonstrates the feasibility of implementing such a motion-correction system in a future design of combined tracking and intracavity coil.
authors.affiliation: Department of Radiology, Dana-Farber Cancer Institute, Boston, Massachusetts 02215, USA. lei_qin@dfci.harvard.edu
authors.forename: Lei
authors.initials: L
authors.lastname: Qin
authors.forename: Ehud J
authors.initials: EJ
authors.lastname: Schmidt
authors.forename: Zion Tsz Ho
authors.initials: ZT
authors.lastname: Tse
authors.forename: Juan
authors.initials: J
authors.lastname: Santos
authors.forename: William S
authors.initials: WS
authors.lastname: Hoge
authors.forename: Clare
authors.initials: C
authors.lastname: Tempany-Afdhal
authors.forename: Kim
authors.initials: K
authors.lastname: Butts-Pauly
authors.forename: Charles L
authors.initials: CL
authors.lastname: Dumoulin
mesh_terms: D016477:Artifacts; D006801:Humans; D007089:Image Enhancement / Q000295:instrumentation*; D007090:Image Interpretation, Computer-Assisted / Q000295:instrumentation*; D021621:Imaging, Three-Dimensional / Q000295:instrumentation*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D008280:Magnetics / Q000295:instrumentation*; D009038:Motion; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity