title: Prospective head motion correction using FID-guided on-demand image navigators.
abstract: We suggest a motion correction concept that employs free-induction-decay (FID) navigator signals to continuously monitor motion and to guide the acquisition of image navigators for prospective motion correction following motion detection.
  
  
  
  Motion causes out-of-range signal changes in FID time series that, and in this approach, initiate the acquisition of an image navigator. Co-registration of the image navigator to a reference provides rigid-body-motion parameters to facilitate prospective motion correction. Both FID and image navigator are integrated into a prototype magnetization-prepared rapid gradient-echo (MPRAGE) sequence. The performance of the method is investigated using image quality metrics and the consistency of brain volume measurements.
  
  
  
  Ten healthy subjects were scanned (a) while performing head movements (nodding, shaking, and moving in z-direction) and (b) to assess the co-registration performance. Mean absolute errors of 0.27 ± 0.38 mm and 0.19 ± 0.24° for translation and rotation parameters were measured. Image quality was qualitatively improved after correction. Significant improvements were observed in automated image quality measures and for most quantitative brain volume computations after correction.
  
  
  
  The presented method provides high sensitivity to detect head motion while minimizing the time invested in acquiring navigator images. Limits of this implementation arise from temporal resolution to detect motion, false-positive alarms, and registration accuracy. Magn Reson Med 78:193-203, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
authors.affiliation: Advanced Clinical Imaging Technology (HC CMEA SUI DI BM PI), Siemens Healthcare AG, Lausanne, Switzerland.|LTS5, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.|Department of Radiology, University Hospital (CHUV), Lausanne, Switzerland.
authors.forename: Maryna
authors.initials: M
authors.lastname: Waszak
authors.affiliation: Advanced Clinical Imaging Technology (HC CMEA SUI DI BM PI), Siemens Healthcare AG, Lausanne, Switzerland.|LTS5, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.|Department of Radiology, University Hospital (CHUV), Lausanne, Switzerland.
authors.forename: Pavel
authors.initials: P
authors.lastname: Falkovskiy
authors.affiliation: Advanced Clinical Imaging Technology (HC CMEA SUI DI BM PI), Siemens Healthcare AG, Lausanne, Switzerland.|LTS5, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.|Department of Radiology, University Hospital (CHUV), Lausanne, Switzerland.
authors.forename: Tom
authors.initials: T
authors.lastname: Hilbert
authors.affiliation: Advanced Clinical Imaging Technology (HC CMEA SUI DI BM PI), Siemens Healthcare AG, Lausanne, Switzerland.|LTS5, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.|Department of Radiology, University Hospital (CHUV), Lausanne, Switzerland.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Bonnier
authors.affiliation: Advanced Clinical Imaging Technology (HC CMEA SUI DI BM PI), Siemens Healthcare AG, Lausanne, Switzerland.|LTS5, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.|Department of Radiology, University Hospital (CHUV), Lausanne, Switzerland.
authors.forename: Bénédicte
authors.initials: B
authors.lastname: Maréchal
authors.affiliation: Department of Radiology, University Hospital (CHUV), Lausanne, Switzerland.
authors.forename: Reto
authors.initials: R
authors.lastname: Meuli
authors.affiliation: Department of Radiology, University Hospital (CHUV), Lausanne, Switzerland.|Centre d'Imagerie BioMedicale (CIBM), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.|Department of Radiology, University of Geneva, Geneva, Switzerland.
authors.forename: Rolf
authors.initials: R
authors.lastname: Gruetter
authors.affiliation: Advanced Clinical Imaging Technology (HC CMEA SUI DI BM PI), Siemens Healthcare AG, Lausanne, Switzerland.|LTS5, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.|Department of Radiology, University Hospital (CHUV), Lausanne, Switzerland.
authors.forename: Tobias
authors.initials: T
authors.lastname: Kober
authors.affiliation: LTS5, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.|Department of Radiology, University Hospital (CHUV), Lausanne, Switzerland.|Siemens Medical Solutions USA, Inc, Boston MA, USA.
authors.forename: Gunnar
authors.initials: G
authors.lastname: Krueger
mesh_terms: D000328:Adult; D000465:Algorithms; D016477:Artifacts; D001921:Brain / Q000033:anatomy & histology*; D005260:Female; D019416:Head Movements; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D038361:Neuronavigation; D010363:Pattern Recognition, Automated / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted
keywords: FID navigators; MRI; head imaging; image navigators; motion detection; prospective motion correction