Je Miseong, Yang Sunho, Lee Dongjae, Choi Jihye, Yoon Junghee
College of Veterinary Medicine and the Research Institute for Veterinary Science, Seoul National University, Seoul, Republic of Korea.
Front Vet Sci. 2023 Jul 17;10:1156870. doi: 10.3389/fvets.2023.1156870. eCollection 2023.
In veterinary medicine, magnetic resonance imaging (MRI) is widely utilized for brain imaging. But the complex structures of brain tissues can give rise to artifacts such as partial volume averaging in conventional sequences. To address this issue, several studies about double inversion recovery (DIR) sequences have been conducted in human medicine. However, published clinical studies about brain MRI using DIR sequences in dogs are currently lacking. The purpose of this study was to evaluate the magnetic resonance features of single-slab 3D DIR sequences in the normal canine brain.
Five healthy Beagle dogs were examined and the following pulse sequences were acquired for each: (1) spin-echo T2-weighted (T2W), (2) fluid attenuated inversion recovery (FLAIR), (3) gray matter (GM) selective, and (4) white matter (WM) selective single-slab 3D DIR sequence. For qualitative analysis, the distinction between gray and white matter of the cerebral cortex, presence and severity of the image artifacts were assessed for each pulse sequence. In addition, reconstructed images of single-slab 3D DIR sequences were qualitatively evaluated. For quantitative analysis, contrast ratios (CRs), signal-to-noise ratios (SNRs), and contrast-to-noise ratios (CNRs) of the GM, WM and cerebrospinal fluid (CSF) were measured for each pulse sequence.
GM selective 3D DIR was superior to T2W and FLAIR in delineating the boundaries between GM and WM in the overall brain area. Whereas WM selective 3D DIR provided better gray-white matter distinction of the cerebral cortex than T2W and FLAIR at the level of the medulla oblongata, where T2W and FLAIR images exhibited severe partial volume averaging artifacts. In general, the 3D DIR images demonstrated fewer artifacts compared to other sequences, and the reconstructed sagittal and dorsal images of these sequences maintained same spatial resolution as the original transverse images without any image degradation. Both gray and white matter selective 3D DIR sequences effectively suppressed unwanted signals, thereby providing high contrast between gray and white matter. Findings from this study could serve as a foundation for further studies on DIR sequences for the evaluation of brain diseases in dogs.
在兽医学中，磁共振成像（MRI）被广泛用于脑部成像。但脑组织的复杂结构会在传统序列中产生诸如部分容积平均等伪影。为解决这一问题，人类医学领域已开展了多项关于双反转恢复（DIR）序列的研究。然而，目前尚缺乏关于犬类使用DIR序列进行脑部MRI的已发表临床研究。本研究的目的是评估单层面三维DIR序列在正常犬脑的磁共振特征。
对5只健康的比格犬进行检查，为每只犬采集以下脉冲序列：（1）自旋回波T2加权（T2W）序列、（2）液体衰减反转恢复（FLAIR）序列、（3）灰质（GM）选择性序列以及（4）白质（WM）选择性单层面三维DIR序列。对于定性分析，评估每个脉冲序列中大脑皮质灰质与白质的区分情况、图像伪影的存在及严重程度。此外，对单层面三维DIR序列的重建图像进行定性评估。对于定量分析，测量每个脉冲序列中GM、WM和脑脊液（CSF）的对比率（CRs）、信噪比（SNRs）和对比噪声比（CNRs）。
在勾勒整个脑区GM与WM之间的边界方面，GM选择性三维DIR序列优于T2W和FLAIR序列。而在延髓水平，WM选择性三维DIR序列在大脑皮质的灰白质区分上比T2W和FLAIR序列更好，在该水平T2W和FLAIR图像表现出严重的部分容积平均伪影。总体而言，与其他序列相比，三维DIR图像显示的伪影更少，这些序列的矢状面和背面重建图像保持了与原始横断面图像相同的空间分辨率，且无任何图像质量下降。灰质和白质选择性三维DIR序列均有效抑制了不需要的信号，从而在灰质和白质之间提供了高对比度。本研究结果可为进一步研究DIR序列用于评估犬类脑部疾病奠定基础。
