Hetherington Hoby P, Hamid Hamada, Kulas Joseph, Ling Geoffrey, Bandak Faris, de Lanerolle Nihal C, Pan Jullie W
Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA; Department of Neurosurgery, Yale University School of Medicine, New Haven, Connecticut, USA.
Magn Reson Med. 2014 Apr;71(4):1358-67. doi: 10.1002/mrm.24814. Epub 2013 Aug 5.
Up to 19% of veterans returning from the wars in Iraq and Afghanistan have a history of mild traumatic brain injury with 70% associated with blast exposure. Tragically, 20-50% of this group reports persistent symptoms, including memory loss. Unfortunately, routine clinical imaging is typically normal, making diagnosis and clinical management difficult. The goal of this work was to develop methods to acquire hippocampal MRSI at 7 T and evaluate their sensitivity to detect injury in veterans with mild traumatic brain injury.
At 7 T, hippocampal MRSI measurements are limited by: (1) poor B(0) homogeneity; (2) insufficient B(1)(+) strength and homogeneity; and (3) chemical shift dispersion artifacts. To overcofme these limitations we: (1) used third degree B(0) shimming; (2) an inductively decoupled transceiver array with radiofrequency shimming; and (3) a volume localized single slice sequence using radiofrequency shimming-based outer volume suppression.
In 20 controls and 25 veterans with mild traumatic brain injury due to blast exposure with memory impairment, hippocampal N-acetyl aspartate to choline (P < 0.001) and N-acetyl aspartate to creatine (P < 0.001) were decreased in comparison to control subjects.
With the appropriate methods robust spectroscopic imaging of the hippocampus can be carried out at 7 T. MRSI at 7 T can detect hippocampal injury in veterans with mild traumatic brain injury.
从伊拉克和阿富汗战争归来的退伍军人中，高达19%有轻度创伤性脑损伤史，其中70%与爆炸暴露有关。不幸的是，该群体中有20 - 50%报告有持续症状，包括记忆力减退。遗憾的是，常规临床成像通常正常，这使得诊断和临床管理变得困难。这项工作的目标是开发在7T下获取海马磁共振波谱成像（MRSI）的方法，并评估其对检测轻度创伤性脑损伤退伍军人损伤的敏感性。
在7T时，海马MRSI测量受到以下限制：（1）B(0)均匀性差；（2）B(1)(+)强度和均匀性不足；（3）化学位移分散伪影。为克服这些限制，我们：（1）使用三阶B(0)匀场；（2）带有射频匀场的电感去耦收发阵列；（3）使用基于射频匀场的外容积抑制的容积定位单切片序列。
在20名对照者和25名因爆炸暴露导致轻度创伤性脑损伤且有记忆障碍的退伍军人中，与对照者相比，海马中N - 乙酰天门冬氨酸与胆碱的比值（P < 0.001）以及N - 乙酰天门冬氨酸与肌酸的比值（P < 0.001）降低。
通过适当的方法，可以在7T下对海马进行可靠的波谱成像。7T下的MRSI能够检测轻度创伤性脑损伤退伍军人的海马损伤。
