Sun Hongfu, Wilman Alan H
Department of Biomedical Engineering, University of Alberta, Edmonton, Canada.
Magn Reson Med. 2015 May;73(5):1932-8. doi: 10.1002/mrm.25316. Epub 2014 Jun 17.
To perform quantitative susceptibility mapping (QSM) in negligible acquisition time and apply it to measuring iron-rich subcortical gray matter.
Whole brain QSM was performed using single-shot gradient echo-planar imaging (EPI) in under 7 seconds on a standard 1.5 T system for imaging brain iron in subcortical gray matter. The method was compared to a standard 6-minute gradient recalled echo (GRE) QSM acquisition in healthy subjects. Region-of-interest QSM measurements were compared between methods in six subcortical gray-matter nuclei and two white matter territories.
EPI-QSM provided similar mean susceptibility values to standard GRE-QSM in iron-rich subcortical gray matter regions, while providing greater than 50-fold scan time reduction. Blurring from the low spatial resolution and transverse relaxation decay of EPI affected edges but had negligible effect on whole subcortical nuclei measurements, which had a high correlation (R(2) = 0.96) to estimated iron content.
EPI-QSM can be performed in several seconds, which enables expansion of brain iron studies of subcortical gray matter to cases where time is limited and to existing MRI studies that already uses gradient echo EPI.
在极短的采集时间内进行定量磁化率成像（QSM），并将其应用于测量富含铁的皮质下灰质。
在标准1.5T系统上，使用单次激发梯度回波平面成像（EPI）在7秒内对全脑进行QSM，以成像皮质下灰质中的脑铁。将该方法与健康受试者中标准的6分钟梯度回波（GRE）QSM采集进行比较。在六个皮质下灰质核团和两个白质区域比较两种方法的感兴趣区QSM测量值。
EPI-QSM在富含铁的皮质下灰质区域提供了与标准GRE-QSM相似的平均磁化率值，同时扫描时间减少了50倍以上。EPI的低空间分辨率和横向弛豫衰减导致的模糊影响了边缘，但对整个皮质下核团测量的影响可忽略不计，这些测量与估计的铁含量具有高度相关性（R(2) = 0.96）。
EPI-QSM可以在几秒钟内完成，这使得皮质下灰质的脑铁研究能够扩展到时间有限的病例以及已经使用梯度回波EPI的现有MRI研究中。
