Kan Hirohito, Arai Nobuyuki, Kasai Harumasa, Kunitomo Hiroshi, Hirose Yasujiro, Shibamoto Yuta
Department of Radiology, Nagoya City University Hospital, 1-Kawasumi, Mizuho-cho Mizuho-ku, Nagoya City, Aichi 4678602, Japan.
Magn Reson Imaging. 2017 Oct;42:37-42. doi: 10.1016/j.mri.2017.05.002. Epub 2017 May 16.
To evaluate the accuracy of susceptibility estimated from the principles of echo shifting with a train of observations (PRESTO) sequence using a 1.5T MRI system, we conducted experiments on the human brain using the PRESTO sequence and compared our results with the susceptibility obtained from spoiled gradient-recalled echo (GRE) sequence with flow compensation using quantitative susceptibility mapping (QSM) reconstruction.
Experiments on the human brain were conducted on 12 healthy volunteers (27±4years) using PRESTO and spoiled GRE sequences on a 1.5T scanner. The PRESTO sequence is an echo-shifted gradient echo sequence that allows high susceptibility sensitivity and rapid acquisition because of TE>TR compared with the spoiled GRE sequence. QSM analysis was performed on the obtained phase images using the iLSQR method. Estimated susceptibility maps were used for region of interest analyses and estimation of line profiles through iron-rich tissue and major vessels.
Our results demonstrated that susceptibility maps were accurately estimated, without error, by QSM analysis of PRESTO and spoiled GRE sequences. Acquisition time in the PRESTO sequence was reduced by 43% compared with that in the spoiled GRE sequence. Differences did exist between susceptibility maps in PRESTO and spoiled GRE sequences for visualization and quantitative values of major blood vessels and the areas around them CONCLUSION: The PRESTO sequence enables correct estimation of tissue susceptibility with rapid acquisition and may be useful for QSM analysis of clinical use of 1.5T scanners.
为了评估使用1.5T磁共振成像（MRI）系统通过一系列观察的回波移位原理（PRESTO）序列估计的磁化率准确性，我们使用PRESTO序列对人脑进行了实验，并将我们的结果与通过定量磁化率成像（QSM）重建的具有流动补偿的扰相梯度回波（GRE）序列获得的磁化率进行了比较。
在12名健康志愿者（27±4岁）身上使用1.5T扫描仪上的PRESTO序列和扰相GRE序列对人脑进行实验。PRESTO序列是一种回波移位梯度回波序列，由于与扰相GRE序列相比TE>TR，因此具有高磁化率敏感性和快速采集能力。使用iLSQR方法对获得的相位图像进行QSM分析。估计的磁化率图用于感兴趣区域分析以及通过富铁组织和主要血管的线轮廓估计。
我们的结果表明，通过对PRESTO序列和扰相GRE序列进行QSM分析，可以准确无误地估计磁化率图。与扰相GRE序列相比，PRESTO序列的采集时间减少了43%。PRESTO序列和扰相GRE序列的磁化率图在主要血管及其周围区域的可视化和定量值方面确实存在差异。结论：PRESTO序列能够快速采集并正确估计组织磁化率，可能对1.5T扫描仪的临床QSM分析有用。
