title: Ultrashort echo time (UTE) imaging using gradient pre-equalization and compressed sensing.
abstract: Ultrashort echo time (UTE) imaging is a well-known technique used in medical MRI, however, the implementation of the sequence remains non-trivial. This paper introduces UTE for non-medical applications and outlines a method for the implementation of UTE to enable accurate slice selection and short acquisition times. Slice selection in UTE requires fast, accurate switching of the gradient and r.f. pulses. Here a gradient "pre-equalization" technique is used to optimize the gradient switching and achieve an effective echo time of 10μs. In order to minimize the echo time, k-space is sampled radially. A compressed sensing approach is used to minimize the total acquisition time. Using the corrections for slice selection and acquisition along with novel image reconstruction techniques, UTE is shown to be a viable method to study samples of cork and rubber with a shorter signal lifetime than can typically be measured. Further, the compressed sensing image reconstruction algorithm is shown to provide accurate images of the samples with as little as 12.5% of the full k-space data set, potentially permitting real time imaging of short T2(*) materials.
authors.affiliation: Department of Chemical Engineering and Biotechnology, University of Cambridge, New Museums Site, Pembroke Street, Cambridge CB2 3RA, United Kingdom. Electronic address: htf21@cam.ac.uk.
authors.forename: Hilary T
authors.initials: HT
authors.lastname: Fabich
authors.affiliation: Department of Chemical Engineering and Biotechnology, University of Cambridge, New Museums Site, Pembroke Street, Cambridge CB2 3RA, United Kingdom.
authors.forename: Martin
authors.initials: M
authors.lastname: Benning
authors.affiliation: Department of Chemical Engineering and Biotechnology, University of Cambridge, New Museums Site, Pembroke Street, Cambridge CB2 3RA, United Kingdom.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Sederman
authors.affiliation: Department of Chemical Engineering and Biotechnology, University of Cambridge, New Museums Site, Pembroke Street, Cambridge CB2 3RA, United Kingdom.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Holland
keywords: Compressed sensing; Gradient pre-equalization; MRI; UTE; Ultrashort echo time