title: Real-time MRI of speaking at a resolution of 33 ms: undersampled radial FLASH with nonlinear inverse reconstruction.
abstract: Dynamic MRI studies of the upper airway during speaking, singing or swallowing are complicated by the need for high temporal resolution and the presence of air-tissue interfaces that may give rise to image artifacts such as signal void and geometric distortions. This work exploits a recently developed real-time MRI technique to address these challenges for monitoring speech production at 3 T. The method combines a short-echo time radial FLASH MRI sequence (pulse repetition time/echo time = 2.22/1.44 ms; flip angle 5°) with pronounced undersampling (15 radial spokes per image) and image reconstruction by regularized nonlinear inversion. The resulting serial images at 1.5 mm in-plane resolution and 33.3 ms acquisition time are free of motion or susceptibility artifacts. This application focuses on a dynamic visualization of the main articulators during natural speech production (Standard Modern German). Respective real-time MRI movies at 30 frames per second clearly demonstrate the spatiotemporal coordination of lips, tongue, velum, and larynx for generating vowels, consonants, and coarticulations. The quantitative results for individual phonetic events are in agreement with previous non-MRI findings.
authors.affiliation: Biomedizinische NMR Forschungs GmbH am Max-Planck-Institut für biophysikalische Chemie, Göttingen, Germany.
authors.forename: Aaron
authors.initials: A
authors.lastname: Niebergall
authors.forename: Shuo
authors.initials: S
authors.lastname: Zhang
authors.forename: Esther
authors.initials: E
authors.lastname: Kunay
authors.forename: Götz
authors.initials: G
authors.lastname: Keydana
authors.forename: Michael
authors.initials: M
authors.lastname: Job
authors.forename: Martin
authors.initials: M
authors.lastname: Uecker
authors.forename: Jens
authors.initials: J
authors.lastname: Frahm
mesh_terms: D000328:Adult; D003199:Computer Systems; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D007830:Larynx / Q000033:anatomy & histology* / Q000502:physiology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D017711:Nonlinear Dynamics; D015203:Reproducibility of Results; D018401:Sample Size; D012680:Sensitivity and Specificity; D013060:Speech / Q000502:physiology*; D013068:Speech Production Measurement / Q000379:methods*; D055815:Young Adult