Selective 3D ultrashort TE imaging: comparison of “dual-echo” acquisition and magnetization preparation for improving short-T 2 contrast
- 282 Downloads
The objective of this study was to compare two different schemes for long-T 2 component suppression in ultrashort echo-time (UTE) imaging. The aim was to increase conspicuity of short-T 2 components accessible by the UTE technique.
Materials and methods
A “dual-echo” and a magnetization-preparation approach for long-T 2 and fat suppression were implemented on clinical scanners. Both techniques were compared in 3D UTE exams on healthy volunteers regarding short-T 2 Signal-to-noise ratio (SNR), long-T 2 suppression quality, and scan efficiency. A quantitative SNR evaluation was performed using ankle scans of six volunteers. T 2 suppression profiles were simulated for both approaches to facilitate interpretation of the observations.
At 1.5 T, both techniques perform equally well in suppressing long-T 2 components and fat. Magnetization preparation requires more shimming effort due to the use of narrow-band pulses, while the “dual-echo” technique requires a post-processing step to form a subtraction image. For scans with a short repetition time (TR), the “dual-echo” approach is much faster than the magnetization preparation, which depends on slow T 1 recovery between preparation steps. The SNR comparison shows slightly higher short-T 2 SNR for the “dual-echo” approach. At 3.0 T, magnetization preparation becomes more challenging due to stronger off-resonance effects.
Both techniques are well suited for long-T 2 suppression and offer comparable short-T 2 SNR. However, the “dual-echo” approach has strong advantages in terms of scan efficiency and off-resonance behavior.
KeywordsMR imaging Ultrashort TE imaging 3D imaging Long-T2 suppression Musculoskeletal imaging
- 1.Pauly J, Conolly S, Nishimura D, Macovski A (1989) Slice-selective excitation for very short T 2 species. In: Proceedings 8th annual meeting SMRM, vol 28Google Scholar
- 5.Reichert IL, Benjamin M, Gatehouse PD, Chappell KE, Holmes J, He T, Bydder GM (2004) Magnetic resonance imaging of Periosteum with ultrashort TE pulse sequences. Magn Reson Med 19:99–107Google Scholar
- 10.Crowe LA, Wang YX, Gatehouse P, Tessier J, Waterton J, Robert P, Bydder G, Firmin DN (2005) Ex vivo MR imaging of atherosclerotic rabbit aorta labelled with USPIO—Enhancement of iron loaded regions in UTE imaging. In: Proc Intl Soc Mag Reson Med., vol 13, p 115Google Scholar
- 12.Pauly J, Conolly S, Macovski A (1992) Suppression of long T 2 components for short T 2 imaging. J Magn Reson Imaging 2:145Google Scholar
- 18.Liang ZP, Lauterbur PC (2000) Principles of magnetic resonance imaging. IEEE, Inc., New YorkGoogle Scholar
- 20.Gurney P, Larson P, Nishimura D (2005) Long-T2 suppressed ultra short-TE 3DPR imaging. In: Proc Intl Soc Mag Reson Med., vol 13, p 787Google Scholar
- 25.Larson PE, Vidarsson L, Pauly JM, Nishimura DG (2005) Linear combination filtering long-T2* suppression in ultra-short echo time (UTE) imaging. In: Proc Intl Soc Mag Reson Med., vol 13, p 2264Google Scholar