Improved encoding strategy for CPMG-based Bloch-Siegert B1+ mapping
Improved encoding strategy for CPMG-based Bloch-Siegert B1+ mapping
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DOI：
10.1002/mrm.23232
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发表时间：
2012-08-01
影响因子：
3.3
通讯作者：
Jakob, P. M.
中科院分区：
文献类型：
--
作者：
Sturm, V. J. F.;Basse-Luesebrink, T. C.;Jakob, P. M.
Bloch-Siegert (BS) based B?1+ mapping methods use off-resonant pulses to encode quantitative B?1+ information into the signal phase. It was recently shown that the principle behind BS-based B?1+ mapping can be expanded from spin echo (BS-SE) and gradient-echo (BS-FLASH) based BS B?1+ mapping to methods such as Carr, Purcell, Meiboom, Gill (CPMG)-based turbo-spin echo (BS-CPMG-TSE) and multi-spin echo (BS-CPMG-MSE) imaging. If CPMG conditions are preserved, BS-CPMG-TSE allows fast acquisition of the B?1+ information and BS-CPMG-MSE enables simultaneous mapping of B?1+, M0, and T2. To date, however, two separate MRI experiments must be performed to enable the calculation of B?1+ maps. This study investigated a modified encoding strategy for CPMG BS-based methods to overcome this limitation. By applying a bipolar off-resonant BS pulse before the refocusing pulse train, the needed phase information was able to be encoded into different echo images of one echo train. Thus, this technique allowed simultaneous B?1+ and T2 mapping in a single BS-CPMG-MSE experiment. To allow single-shot B?1+ mapping, this method was also applied to turbo-spin echo imaging. Furthermore, the presented modification intrinsically minimizes phase-based image artifacts in BS-CPMG-TSE experiments. Magn Reson Med, 2012. (C) 2011 Wiley Periodicals, Inc.
