Spin-echo magnetic resonance spectroscopic imaging at 7 T with frequency-modulated refocusing pulses.
Journal Article (Journal Article)
Two approaches to high-resolution SENSE-encoded magnetic resonance spectroscopic imaging (MRSI) of the human brain at 7 Tesla (T) with whole-slice coverage are described. Both sequences use high-bandwidth radiofrequency pulses to reduce chemical shift displacement artifacts, SENSE-encoding to reduce scan time, and dual-band water and lipid suppression optimized for 7 T. Simultaneous B0 and transmit B1 mapping was also used for both sequences to optimize field homogeneity using high-order shimming and determine optimum radiofrequency transmit level, respectively. One sequence ("Hahn-MRSI") used reduced flip angle (90°) refocusing pulses for lower radiofrequency power deposition, while the other sequence used adiabatic fast passage refocusing pulses for improved sensitivity and reduced signal dependence on the transmit-B1 level. In four normal subjects, adiabatic fast passage-MRSI showed a signal-to-noise ratio improvement of 3.2±0.5 compared to Hahn-MRSI at the same spatial resolution, pulse repetition time, echo time, and SENSE-acceleration factor. An interleaved two-slice Hahn-MRSI sequence is also demonstrated to be experimentally feasible.
Full Text
Duke Authors
Cited Authors
- Zhu, H; Soher, BJ; Ouwerkerk, R; Schär, M; Barker, PB
Published Date
- May 2013
Published In
Volume / Issue
- 69 / 5
Start / End Page
- 1217 - 1225
PubMed ID
- 22692894
Pubmed Central ID
- PMC3443531
Electronic International Standard Serial Number (EISSN)
- 1522-2594
Digital Object Identifier (DOI)
- 10.1002/mrm.24357
Language
- eng
Conference Location
- United States