Image quality in non-gated versus gated reconstruction of tongue motion using magnetic resonance imaging: a comparison using automated image processing
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The use of gated or ECG triggered MR is a well-established technique and developments in coil technology have enabled this approach to be applied to areas other than the heart. However, the image quality of gated (ECG or cine) versus non-gated or real-time has not been extensively evaluated in the mouth. We evaluate two image sequences by developing an automatic image processing technique which compares how well the image represents known anatomy.
Four subjects practised experimental poly-syllabic sentences prior to MR scanning. Using a 1.5 T MR unit, we acquired comparable gated (using an artificial trigger) and non-gated sagittal images during speech. We then used an image processing algorithm to model the image grey along lines that cross the airway. Each line involved an eight parameter non-linear equation to model of proton densities, edges, and dimensions.
Gated and non-gated images show similar spatial resolution, with non-gated images being slightly sharper (10% better resolution, less than 1 pixel). However, the gated sequences generated images of substantially lower inherent noise, and substantially better discrimination between air and tissue. Additionally, the gated sequences demonstrate a very much greater temporal resolution.
Overall, image quality is better with gated imaging techniques, especially given their superior temporal resolution. Gated techniques are limited by the repeatability of the motions involved, and we have shown that speech to a metronome can be sufficiently repeatable to allow high-quality gated magnetic resonance imaging images. We suggest that gated sequences may be useful for evaluating other types of repetitive movement involving the joints and limb motions.
KeywordsMR imaging ECG gated Non-ECG gated Image quality Comparison Automatic processing Non-linear Image processing Optimization Markov Monte-Carlo Signal Noise Ratio Tongue Speech Phrase Utterance
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- 8.Demolin D, Lecuit V, Metens T, Nazarian B, Soquet A (1998) Magnetic resonance measurements of the velum port opening. In: Proceedings of the 5th international conference on spoken language processing (ICSLP), Sydney, pp 425–429. http://www.isca-speech.org/archive/icslp_1998/i98_0532.html. Accessed 5 2008
- 9.Demolin D, Metens T, Soquet A (2000) Real time MRI and articulatory coordinations in vowels. In: Proceedings of the 5th seminar on speech production: models and data. Universität München, Kloster Seeon, pp 93–96Google Scholar
- 10.Engwall O (2004) From non-gated MRI to 3D tongue movements.In: Proceedings of the 8th international conference on spoken language processing (ICSLP 2004), Jeju Island, Korea, vol II, pp 1109–1112. http://www.speech.kth.se/ctt/publications/papers04/icslp2004_realtime.pdf Accessed 5 2008
- 18.Joye WA, Mandel E (2003) New features of SAOImage DS9. In: Payne HE, Jedrzejewski RI, Hook RN (eds) Astronomical data analysis software and systems XII ASP conference series, vol 295, p 489Google Scholar