Baboli Mehran, Storey Pippa, Sood Terlika Pandit, Fogarty Justin, Moccaldi Melanie, Lewin Alana, Moy Linda, Kim Sungheon Gene
Bernard and Irene Schwartz Center for Biomedical Imaging, Center for Advanced Imaging Innovation and Research (CAI2R), Department of Radiology, New York University School of Medicine, New York, New York, USA.
Department of Radiology, Weill Cornell Medicine, New York, New York, USA.
Magn Reson Med. 2021 Jul;86(1):33-45. doi: 10.1002/mrm.28692. Epub 2021 Feb 2.
To develop a simultaneous dual-slab three-dimensional gradient-echo spectroscopic imaging (GSI) technique with frequency drift compensation for rapid (<6 min) bilateral measurement of fatty acid composition (FAC) in mammary adipose tissue.
A bilateral GSI sequence was developed using a simultaneous dual-slab excitation followed by 128 monopolar echoes. A short train of navigator echoes without phase or partition encoding was included at the beginning of each pulse repetition time period to correct for frequency variation caused by respiration and heating of the cryostat. Voxel-wise spectral fitting was applied to measure the areas of the lipid spectral peaks to estimate the number of double-bond (ndb), number of methylene-interrupted double-bond (nmidb), and chain length (cl). The proposed method was tested in an oil phantom and 10 postmenopausal women to assess the influence of the frequency variation on FAC estimation.
The frequency drift observed over 5:27 min during the phantom scan was about 10 Hz. Phase correction based on the navigator reduced the median error of ndb, nmidb, and cl from 9.7%, 17.6%, and 3.2% to 2.1%, 9.5%, and 2.8%, respectively. The in vivo data showed a mean ± standard deviation frequency drift of 17.4 ± 2.5 Hz, with ripples at 0.3 ± 0.1 Hz. Our reconstruction algorithm successfully separated signals from the left and right breasts with negligible residual aliasing. Phase correction reduced the interquartile range within each subject's adipose tissue of ndb, nmidb, and cl by 18.4 ± 10.6%, 18.5 ± 13.9%, and 18.4 ± 10.6%, respectively.
This study shows the feasibility of obtaining bilateral spectroscopic imaging data in the breast and that incorporation of a frequency navigator improves the estimation of FAC.
开发一种具有频率漂移补偿功能的同步双层面三维梯度回波光谱成像（GSI）技术，用于快速（<6分钟）双侧测量乳腺脂肪组织中的脂肪酸组成（FAC）。
采用同步双层面激发及128个单极回波，开发了一种双侧GSI序列。在每个脉冲重复时间周期开始时，加入一组短的导航回波，该回波不进行相位或分区编码，以校正由呼吸和低温恒温器加热引起的频率变化。采用体素级光谱拟合来测量脂质光谱峰的面积，以估计双键数（ndb）、亚甲基间断双键数（nmidb）和链长（cl）。该方法在油模体和10名绝经后女性中进行测试，以评估频率变化对FAC估计的影响。
在模体扫描的5分27秒内观察到的频率漂移约为10 Hz。基于导航回波的相位校正将ndb、nmidb和cl的中位数误差分别从9.7%、17.6%和3.2%降低至2.1%、9.5%和2.8%。体内数据显示平均±标准差频率漂移为17.4±2.5 Hz，伴有0.3±0.1 Hz的波动。我们的重建算法成功地分离了左右乳房的信号，残余混叠可忽略不计。相位校正使每个受试者脂肪组织内ndb、nmidb和cl的四分位数间距分别减少了18.4±10.6%、18.5±13.9%和18.4±10.6%。
本研究表明在乳房中获取双侧光谱成像数据的可行性，并且加入频率导航器可改善FAC的估计。
