PhDMagnetic Resonance Imaging (MRI) has been used to provide high-resolution
tomographic information, valuable in the study of static vocal tract. However,
speech does not present a static behaviour but relies on the continuous and dynamic
interaction of the vocal tract articulators and neighbouring tissues. Thus,
this could make real-time MRI (rt-MRI) an essential tool to assess speech, with
numerous advantages over the current clinical techniques. However, using rt-MRI
to image the upper vocal tract remains challenging; the motion of the articulators,
including the velum is fast while MRI data acquisition is slow thus inherently limiting
temporal resolution. Additionally, an intrinsic loss in SNR, spatial resolution
and/or visual image quality is present. The main focus of this thesis is to increase
clinical reliability of rt-MRI in speech by investigating novel methodologies for the
imaging of velopharyngeal motion. Firstly, commercial rt-MRI protocols at 1.5 T
and 3 T were compared, regarding image quality and temporal resolution compromise.
Optimal imaging protocols were suggested for both eld strengths. This
provided a starting point for future clinical translation and the use of commercial
and currently available protocols to image velopharyngeal motion. Furthermore,
imaging of velopharyngeal motion was further improved with non-standard acquisition
methods, such as non-Cartesian sampling and more advanced reconstruction
schemes. An improved imaging protocol for the assessment of velopharyngeal motion
was suggested. This was based on a highly accelerated radial trajectory with
a novel parallel imaging reconstruction method (radial tt-GRAPPA). The suggested
protocol not only allowed for improved image quality and image sharpness,but it was also viable for future clinical translation regarding o
offline computation
times compared to other reconstruction methodologies also investigated in this
thesis. In summary, this thesis added some novel insights into the eld of speech
rt-MRI, presenting improved and time effcient imaging protocols, adequate for
the assessment of velopharyngeal motion
