Frequency drift in MR spectroscopy at 3T.
Frequency drift in MR spectroscopy at 3T.
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DOI：
10.1016/j.neuroimage.2021.118430
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发表时间：
2021-11-01
期刊：
影响因子：
5.7
通讯作者：
Edden RAE
中科院分区：
文献类型：
--
作者：
Hui SCN;Mikkelsen M;Zöllner HJ;Ahluwalia V;Alcauter S;Baltusis L;Barany DA;Barlow LR;Becker R;Berman JI;Berrington A;Bhattacharyya PK;Blicher JU;Bogner W;Brown MS;Calhoun VD;Castillo R;Cecil KM;Choi YB;Chu WCW;Clarke WT;Craven AR;Cuypers K;Dacko M;de la Fuente-Sandoval C;Desmond P;Domagalik A;Dumont J;Duncan NW;Dydak U;Dyke K;Edmondson DA;Ende G;Ersland L;Evans CJ;Fermin ASR;Ferretti A;Fillmer A;Gong T;Greenhouse I;Grist JT;Gu M;Harris AD;Hat K;Heba S;Heckova E;Hegarty JP 2nd;Heise KF;Honda S;Jacobson A;Jansen JFA;Jenkins CW;Johnston SJ;Juchem C;Kangarlu A;Kerr AB;Landheer K;Lange T;Lee P;Levendovszky SR;Limperopoulos C;Liu F;Lloyd W;Lythgoe DJ;Machizawa MG;MacMillan EL;Maddock RJ;Manzhurtsev AV;Martinez-Gudino ML;Miller JJ;Mirzakhanian H;Moreno-Ortega M;Mullins PG;Nakajima S;Near J;Noeske R;Nordhøy W;Oeltzschner G;Osorio-Duran R;Otaduy MCG;Pasaye EH;Peeters R;Peltier SJ;Pilatus U;Polomac N;Porges EC;Pradhan S;Prisciandaro JJ;Puts NA;Rae CD;Reyes-Madrigal F;Roberts TPL;Robertson CE;Rosenberg JT;Rotaru DG;O'Gorman Tuura RL;Saleh MG;Sandberg K;Sangill R;Schembri K;Schrantee A;Semenova NA;Singel D;Sitnikov R;Smith J;Song Y;Stark C;Stoffers D;Swinnen SP;Tain R;Tanase C;Tapper S;Tegenthoff M;Thiel T;Thioux M;Truong P;van Dijk P;Vella N;Vidyasagar R;Vovk A;Wang G;Westlye LT;Wilbur TK;Willoughby WR;Wilson M;Wittsack HJ;Woods AJ;Wu YC;Xu J;Lopez MY;Yeung DKW;Zhao Q;Zhou X;Zupan G;Edden RAE
梯度线圈和无源匀场组件发热是B 0场中不稳定的常见原因，尤其是在使用梯度密集序列时。本研究的目的是为MR波谱（MRS）期间遇到的典型漂移设定一个基准，通过比较来自大量研究中心的场漂移数据，评估MRI扫描仪上实时场频率锁定的需求。使用来自3家主要供应商的99台3 T MR扫描仪为80个参与研究中心制定了标准化方案。在EPI序列之前和之后采集体模水信号。该方案包括：最小的预备成像;短的fMRI前PRESS; 10分钟的fMRI采集;和长的fMRI后PRESS采集。术前和术后fMRI PRESS均为非水抑制。实时频率稳定/调整在适当时关闭。60台扫描仪重复了第二个数据集的方案。此外，在一个部位进行了3小时后的fMRI MRS采集，以观察梯度温度和漂移率的变化。使用MATLAB进行光谱分析。将fMRI前PRESS数据中的频率漂移与fMRI后前5：20分钟和完整30：00分钟的数据进行比较。测量中位数（四分位距）漂移，并显示在小提琴图中。进行配对t检验以比较fMRI前后的频率漂移。使用FID-A生成模拟体内光谱，以可视化观察到的频率漂移的影响。对于最极端的情况，将模拟频谱与频率轨迹进行卷积。频率漂移对NAA和GABA的影响也被模拟为线性漂移的函数。使用皮尔逊相关系数和组内相关系数（ICC）将重复方案的数据与相应的第一个数据集进行比较。从99台扫描仪收集的数据中，4台因各种原因被排除。因此，最终分析了来自95台扫描仪的数据。对于前5：20分钟（64次瞬变），fMRI前的中位数（四分位距）漂移为0.44（1.29）Hz，fMRI后为0.83（1.29）Hz。在整个30 min（360次瞬变）运行中，该频率增加至3.15（4.02）Hz。fMRI前的平均漂移率为0.29 Hz/min，后为0.43 Hz/min。配对t检验表明fMRI后漂移增加，正如预期的那样（p < 0.05）。与频率漂移卷积的模拟光谱显示，GE、Philips和Siemens扫描仪在fMRI后NAA单态的强度分别降低了26%、44%和18%。ICC表示在不同日期获得的数据集之间具有良好的一致性。单部位长时间采集显示，fMRI后约3小时，漂移率降至0.03 Hz/min。本研究分析了95台3 T MRI扫描仪的频率漂移数据。漂移的中位数水平相对较低（低于1 Hz的5分钟平均值），但最极端的情况下，漂移水平较高。不同扫描仪的漂移程度不同，观察到线性和非线性漂移。
Heating of gradient coils and passive shim components is a common cause of instability in the B0 field, especially when gradient intensive sequences are used. The aim of the study was to set a benchmark for typical drift encountered during MR spectroscopy (MRS) to assess the need for real-time field-frequency locking on MRI scanners by comparing field drift data from a large number of sites. A standardized protocol was developed for 80 participating sites using 99 3T MR scanners from 3 major vendors. Phantom water signals were acquired before and after an EPI sequence. The protocol consisted of: minimal preparatory imaging; a short pre-fMRI PRESS; a ten-minute fMRI acquisition; and a long post-fMRI PRESS acquisition. Both pre- and post-fMRI PRESS were non-water suppressed. Real-time frequency stabilization/adjustment was switched off when appropriate. Sixty scanners repeated the protocol for a second dataset. In addition, a three-hour post-fMRI MRS acquisition was performed at one site to observe change of gradient temperature and drift rate. Spectral analysis was performed using MATLAB. Frequency drift in pre-fMRI PRESS data were compared with the first 5:20 minutes and the full 30:00 minutes of data after fMRI. Median (interquartile range) drifts were measured and showed in violin plot. Paired t-tests were performed to compare frequency drift pre- and post-fMRI. A simulated in vivo spectrum was generated using FID-A to visualize the effect of the observed frequency drifts. The simulated spectrum was convolved with the frequency trace for the most extreme cases. Impacts of frequency drifts on NAA and GABA were also simulated as a function of linear drift. Data from the repeated protocol were compared with the corresponding first dataset using Pearson's and intraclass correlation coefficients (ICC). Of the data collected from 99 scanners, 4 were excluded due to various reasons. Thus, data from 95 scanners were ultimately analyzed. For the first 5:20 min (64 transients), median (interquartile range) drift was 0.44 (1.29) Hz before fMRI and 0.83 (1.29) Hz after. This increased to 3.15 (4.02) Hz for the full 30 min (360 transients) run. Average drift rates were 0.29 Hz/min before fMRI and 0.43 Hz/min after. Paired t-tests indicated that drift increased after fMRI, as expected (p < 0.05). Simulated spectra convolved with the frequency drift showed that the intensity of the NAA singlet was reduced by up to 26%, 44 % and 18% for GE, Philips and Siemens scanners after fMRI, respectively. ICCs indicated good agreement between datasets acquired on separate days. The single site long acquisition showed drift rate was reduced to 0.03 Hz/min approximately three hours after fMRI. This study analyzed frequency drift data from 95 3T MRI scanners. Median levels of drift were relatively low (5-min average under 1 Hz), but the most extreme cases suffered from higher levels of drift. The extent of drift varied across scanners which both linear and nonlinear drifts were observed.
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影响因子：
3.3
作者：
Graedel, Nadine N.;Polimeni, Jonathan R.;Guerin, Bastien;Gagoski, Borjan;Wald, Lawrence L.
通讯作者：
Wald, Lawrence L.
影响因子：
5.7
作者：
Mikkelsen M;Barker PB;Bhattacharyya PK;Brix MK;Buur PF;Cecil KM;Chan KL;Chen DY;Craven AR;Cuypers K;Dacko M;Duncan NW;Dydak U;Edmondson DA;Ende G;Ersland L;Gao F;Greenhouse I;Harris AD;He N;Heba S;Hoggard N;Hsu TW;Jansen JFA;Kangarlu A;Lange T;Lebel RM;Li Y;Lin CE;Liou JK;Lirng JF;Liu F;Ma R;Maes C;Moreno-Ortega M;Murray SO;Noah S;Noeske R;Noseworthy MD;Oeltzschner G;Prisciandaro JJ;Puts NAJ;Roberts TPL;Sack M;Sailasuta N;Saleh MG;Schallmo MP;Simard N;Swinnen SP;Tegenthoff M;Truong P;Wang G;Wilkinson ID;Wittsack HJ;Xu H;Yan F;Zhang C;Zipunnikov V;Zöllner HJ;Edden RAE
通讯作者：
Edden RAE
影响因子：
3.3
作者：
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影响因子：
3.3
作者：
KLOSE, U
通讯作者：
KLOSE, U
影响因子：
3.3
作者：
Ernst, Thomas;Li, Jikun
通讯作者：
Li, Jikun