分类： 生物学 >> 生物物理学 提交时间： 2016-05-12
Zhang, Zihao
Zuo, Zhentao
Wang, Bo
Wei, Ning
Xue, Rong
Zhang, Zihao
Wei, Ning
Deng, Xiaofeng
Zhao, Jizong
Weng, Dehe
An, Jing
Xue, Rong
摘要： Purpose: Time-of-flight (TOF) MR angiography has an advantage of contrast and resolution in ultra-high field (7 T) MRI systems. However, increased specific absorption rate (SAR) prohibits the application of spatial saturation band, leading to venous contamination in maximum intensity projection (MIP) images. Methods: A segmented k-space filling scheme with sparse venous saturation pulses was developed for 7 T TOF-MRA. The effectiveness of the segmented TOF sequence was verified by Bloch equation simulation and experiments on 3 T. The protocol on 7 T was optimized and applied for healthy volunteers and patients with vascular diseases. Results: Segmented TOF achieved equivalent contrast and venous suppression effect as conventional methods, while SAR values had a remarkable reduction and obeyed the limit of a 7 T MRI system. The decreased number of saturation pulses allowed shorter acquisition time than existing solutions. The comparison of segmented TOF and conventional TOF revealed flow direction in vascular diseases. Conclusion: Segmented TOF is proved to be a time-efficient way to achieve high-resolution angiograms without venous contamination at ultra-high field. The sequence holds strong promise for non-contrast clinical diagnosis on cerebrovascular diseases. (C) 2015 Elsevier Inc. All rights reserved.
分类： 生物学 >> 生物物理学 提交时间： 2016-05-05
Deng, Xiaofeng
Xu, Long
Zhang, Yan
Wang, Shuo
Zhao, Yuanli
Cao, Yong
Zhang, Dong
Wang, Rong
Ye, Xun
Wu, Jun
Zhao, Jizong
Deng, Xiaofeng
Xu, Long
Zhang, Yan
Wang, Shuo
Zhao, Yuanli
Cao, Yong
Zhang, Dong
Wang, Rong
Ye, Xun
摘要： The authors attempted to demonstrate the difference in language cortex reorganization between cerebral malformations (AVMs), cavernous malformations (CMs), and gliomas by blood oxygen level-dependent (BOLD) functional magnetic resonance imaging. Clinical and imaging data of 27 AVM patients (AVM-L group), 29 CM patients (CM-L group), and 20 glioma patients (Glioma-L group) were retrospectively reviewed, with lesions overlying the left inferior frontal gyrus (Broca area). As a control, patients with lesions involving the right inferior frontal gyrus were also enrolled, including 14 AVM patients (AVM-R group), 20 CM patients (CM-R group), and 14 glioma patients (Glioma-R group). All patients were right-handed. Lateralization indices (LI) of BOLD signal activations were calculated separately for Broca and Wernicke areas. In AVM-L group, right-sided lateralization of BOLD signals was observed in 10 patients (37.0 %), including 6 in the Broca area alone, 1 in the Wernicke area alone, and 3 in both areas. Three patients (10.3 %) of CM-L group showed right-sided lateralization in both Broca and Wernicke areas, and 1 patient (5.0 %) of Glioma-L group had right-sided lateralization in the Wernicke area alone. A significant difference of right-sided lateralization was observed between the AVM-L group and CM-L group (P = 0.018) and also between the AVM-L group and Glioma-L group (P = 0.027). No patient in AVM-R, CM-R, or Glioma-R groups showed right-sided lateralization. Language cortex reorganization may occur in AVM, CM, and glioma patients when the traditional language cortex was involved by lesions, but the potential of reorganization for CM and glioma patients seems to be insufficient compared with AVM patients.
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