Felix Muñoz1, Yongwan Lim2, Sophia X Cui3, Helmut Stark4, Krishna S Nayak5,2. 1. Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, USA. jdfelix@usc.edu. 2. Ming Hsieh Department of Electrical and Computer Engineering, University of Southern California, Los Angeles, CA, USA. 3. Siemens Medical Solutions USA, Inc., Los Angeles, CA, USA. 4. Stark Contrast, Erlangen, Germany. 5. Department of Biomedical Engineering, University of Southern California, Los Angeles, CA, USA.
Abstract
OBJECTIVE: Speech production MRI benefits from lower magnetic fields due to reduced off-resonance effects at air-tissue interfaces and from the use of dedicated receiver coils due to higher SNR and parallel imaging capability. Here we present a custom designed upper airway coil for 1H imaging at 0.55 Tesla and evaluate its performance in comparison with a vendor-provided prototype 16-channel head/neck coil. MATERIALS AND METHODS: Four adult volunteers were scanned with both custom speech and prototype head-neck coils. We evaluated SNR gains of each of the coils over eleven upper airway volumes-of-interest measured relative to the integrated body coil. We evaluated parallel imaging performance of both coils by computing g-factors for SENSE reconstruction of uniform and variable density Cartesian sampling schemes with R = 2, 3, and 4. RESULTS: The dedicated coil shows approximately 3.5-fold SNR efficiency compared to the head-neck coil. For R = 2 and 3, both uniform and variable density samplings have g-factor values below 1.1 in the upper airway region. For R = 4, g-factor values are higher for both trajectories. DISCUSSION: The dedicated coil configuration allows for a significant SNR gain over the head-neck coil in the articulators. This, along with favorable g values, makes the coil useful in speech production MRI.
OBJECTIVE: Speech production MRI benefits from lower magnetic fields due to reduced off-resonance effects at air-tissue interfaces and from the use of dedicated receiver coils due to higher SNR and parallel imaging capability. Here we present a custom designed upper airway coil for 1H imaging at 0.55 Tesla and evaluate its performance in comparison with a vendor-provided prototype 16-channel head/neck coil. MATERIALS AND METHODS: Four adult volunteers were scanned with both custom speech and prototype head-neck coils. We evaluated SNR gains of each of the coils over eleven upper airway volumes-of-interest measured relative to the integrated body coil. We evaluated parallel imaging performance of both coils by computing g-factors for SENSE reconstruction of uniform and variable density Cartesian sampling schemes with R = 2, 3, and 4. RESULTS: The dedicated coil shows approximately 3.5-fold SNR efficiency compared to the head-neck coil. For R = 2 and 3, both uniform and variable density samplings have g-factor values below 1.1 in the upper airway region. For R = 4, g-factor values are higher for both trajectories. DISCUSSION: The dedicated coil configuration allows for a significant SNR gain over the head-neck coil in the articulators. This, along with favorable g values, makes the coil useful in speech production MRI.
Authors: Andrea Hayes; Julie M Alspaugh; Detlef Bartelt; Molly B Campion; John Eng; Bob W Gayler; Seanne E Henkel; Bronwyn Jones; Arpana Lingaraj; Mahadevappa Mahesh; Mark Rostkowski; Christine P Smith; Judy Haynos Journal: Dysphagia Date: 2009-02-07 Impact factor: 3.438