Optimized inversion recovery sequences for quantitative T1 and magnetization transfer imaging

✍ Scribed by Ke Li; Zhongliang Zu; Junzhong Xu; Vaibhav A. Janve; John C. Gore; Mark D. Does; Daniel F. Gochberg

• Publisher: John Wiley and Sons
• Year: 2010
• Tongue: English
• Weight: 836 KB
• Volume: 64
• Category: Article
• ISSN: 0740-3194
• DOI: 10.1002/mrm.22440

✦ Synopsis

Abstract

Inversion recovery sequences that vary the inversion time (t~i~) have been employed to determine T~1~ and, more recently, quantitative magnetization transfer parameters. Specifically, in previous work, the inversion recovery pulse sequences varied t~i~ only while maintaining a constant delay (t~d~) between repetitions. T~1~ values were determined by fitting to a single exponential function, and quantitative magnetization transfer parameters were then determined by fitting to a biexponential function with an approximate solution. In the current study, new protocols are employed, which vary both t~i~ and t~d~ and fit the data with minimal approximations. Cramer‐Rao lower bounds are calculated to search for acquisition schemes that will maximize the precision efficiencies of T~1~ and quantitative magnetization transfer parameters. This approach is supported by Monte Carlo simulations. The optimal T~1~ schemes are verified by measurements on MnCl~2~ samples. The optimal quantitative magnetization transfer schemes are confirmed by measurements on a series of cross‐linked bovine serum albumin phantoms of varying concentrations. The effects of varying the number of sampling data points are also explored, and a rapid acquisition scheme is demonstrated in vivo. These new optimized quantitative imaging methods provide an improved means for determining T~1~ and magnetization transfer parameter values compared to previous inversion recovery based methods. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.