R2* estimation using "in-phase" echoes in the presence of fat: the effects of complex spectrum of fat.
R2* estimation using "in-phase" echoes in the presence of fat: the effects of complex spectrum of fat.
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DOI：
10.1002/jmri.23851
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发表时间：
2013-03
影响因子：
4.4
通讯作者：
Reeder, Scott B.
中科院分区：
文献类型：
--
作者：
Hernando, Diego;Kuehn, Jens-Peter;Mensel, Birger;Voelzke, Henry;Puls, Ralf;Hosten, Norbert;Reeder, Scott B.
To investigate R2* mapping robustness in the presence of fat using in-phase echoes, without and with spectral modeling of fat (single-peak and multi-peak models, respectively), using varying numbers of echoes. Data from 88 volunteers (men/women: 52/36, ages: 55.4±12.2) were randomly chosen according to MRI liver fat-fraction (%), and classified into 6 fat-fraction groups (1: 20 cases, 0–<10%; 2: 20 cases, 10–<20%; 3: 20 cases, 20–<30%; 4: 20 cases, 30–<40%; 5: 8 cases >40% liver fat; 6: subcutaneous fat from all cases). R2* maps obtained from 5 in-phase echoes (echo times: 4.8–23.8ms) were retrospectively reconstructed using single-peak and multi-peak fat modeling. R2* maps were also calculated using different numbers (2–5) of echoes. Multi-peak fat corrected R2* mapping is feasible from in-phase echoes, with noise performance comparable to single-peak R2* when using ≥4 echoes. Single-peak R2* showed poor robustness to varying echo time combinations in the presence of fat, where using few echoes resulted in large errors. These errors can be reduced using more echoes, or fully corrected using multi-peak fat modeling. The mean R2* increased significantly with increasing fat-fraction when using single-peak R2* for any TE combination (p<0.001), but did not vary when using multi-peak R2* for any TE combination (p≥0.158). R2* mapping uncorrected for spectral complexity of fat contains protocol and fat-dependent errors (lack of robustness) in tissues with high fat content. Accounting for complex fat spectrum improves robustness and accuracy of signal fitting, with modest noise performance loss.
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