Comparison of diffusion tensor imaging by cardiovascular magnetic resonance and gadolinium enhanced 3D image intensity approaches to investigation of structural anisotropy in explanted rat hearts.
Comparison of diffusion tensor imaging by cardiovascular magnetic resonance and gadolinium enhanced 3D image intensity approaches to investigation of structural anisotropy in explanted rat hearts.
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DOI：
10.1186/s12968-015-0129-x
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发表时间：
2015-04-29
期刊：
影响因子：
--
通讯作者：
Gilbert SH
中科院分区：
文献类型：
--
作者：
Bernus O;Radjenovic A;Trew ML;LeGrice IJ;Sands GB;Magee DR;Smaill BH;Gilbert SH
心血管磁共振（CMR）可以通过3D FLASH和弥散张量成像（DTI）两种方法，对心肌细胞及其层流阵列的局部方向进行互补。8颗离体大鼠心脏灌注Gd-DTPA造影剂和固定剂，在9.4T磁体中成像，采用两种采集方式：3D快速低角度拍摄（FLASH）成像，体素为50 × 50 × 50 μm；三维自旋回波DTI成像，单极扩散梯度为3.6 ms，分离11.5 ms，体素为200 × 200 × 200 μm。探讨了每种方法对成像参数的敏感性。FLASH数据显示具有高信号的体素层流对齐，与假设的薄片之间的间隙对比度优势保持一致。利用结构张量（ST）分析确定了信号连续性的最大（v1ST）、中间（v2ST）和最小（v3ST）扩展正交方向。对DTI数据进行分析，确定扩散程度的最（e1DTI）、中间（e2DTI）和最小（e3DTI）正交特征向量。对FLASH和DTI方法的对应关系进行了测量和评价。在整个左心室，FLASH信号的最大延伸方向（v1ST）与弥散（e1DTI）一致（间隔的代表性差异为13.3±6.7°：中位数±绝对偏差），两者都与预期的心肌细胞长轴的局部方向一致。而FLASH信号连续性（v3ST）和扩散（e3ST）最小方向的取向差异较大，可达27.9±17.4°。FLASH （v3ST）和DTI （e3DTI）与FLASH图像中直接测量的层流阵列相比较。对于FLASH，结构张量计算的v3ST与直接测量的FLASH层流阵列正常值之间的差异为侧壁9±7°，间隔7±9°（中位数±四分位数范围），对于DTI，计算的v3DTI与直接测量的FLASH层流阵列正常值之间的差异为22±14°和61±53.4°。DTI对扩散方向的数量和固定后72小时内的时间相对不敏感，但受到b值（通过固定梯度脉冲分离修改扩散梯度脉冲强度来缩放）的适度影响。最佳DTI参数为b = 1000 mm/s2和12个扩散方向。FLASH采集对所探索的图像处理参数相对不敏感。我们表明，FLASH的ST分析是测量心脏微观结构的有用和准确的工具。虽然FLASH和DTI方法似乎都有希望绘制整个心肌的肌细胞排列，但每种方法推断的交叉肌细胞各向异性之间的显着差异需要考虑其各自的局限性。本文的在线版本（doi:10.1186/s12968-015-0129-x）包含补充材料，可供授权用户使用。
Cardiovascular magnetic resonance (CMR) can through the two methods 3D FLASH and diffusion tensor imaging (DTI) give complementary information on the local orientations of cardiomyocytes and their laminar arrays. Eight explanted rat hearts were perfused with Gd-DTPA contrast agent and fixative and imaged in a 9.4T magnet by two types of acquisition: 3D fast low angle shot (FLASH) imaging, voxels 50 × 50 × 50 μm, and 3D spin echo DTI with monopolar diffusion gradients of 3.6 ms duration at 11.5 ms separation, voxels 200 × 200 × 200 μm. The sensitivity of each approach to imaging parameters was explored. The FLASH data showed laminar alignments of voxels with high signal, in keeping with the presumed predominance of contrast in the interstices between sheetlets. It was analysed, using structure-tensor (ST) analysis, to determine the most (v1ST), intermediate (v2ST) and least (v3ST) extended orthogonal directions of signal continuity. The DTI data was analysed to determine the most (e1DTI), intermediate (e2DTI) and least (e3DTI) orthogonal eigenvectors of extent of diffusion. The correspondence between the FLASH and DTI methods was measured and appraised. The most extended direction of FLASH signal (v1ST) agreed well with that of diffusion (e1DTI) throughout the left ventricle (representative discrepancy in the septum of 13.3 ± 6.7°: median ± absolute deviation) and both were in keeping with the expected local orientations of the long-axis of cardiomyocytes. However, the orientation of the least directions of FLASH signal continuity (v3ST) and diffusion (e3ST) showed greater discrepancies of up to 27.9 ± 17.4°. Both FLASH (v3ST) and DTI (e3DTI) where compared to directly measured laminar arrays in the FLASH images. For FLASH the discrepancy between the structure-tensor calculated v3ST and the directly measured FLASH laminar array normal was of 9 ± 7° for the lateral wall and 7 ± 9° for the septum (median ± inter quartile range), and for DTI the discrepancy between the calculated v3DTI and the directly measured FLASH laminar array normal was 22 ± 14° and 61 ± 53.4°. DTI was relatively insensitive to the number of diffusion directions and to time up to 72 hours post fixation, but was moderately affected by b-value (which was scaled by modifying diffusion gradient pulse strength with fixed gradient pulse separation). Optimal DTI parameters were b = 1000 mm/s2 and 12 diffusion directions. FLASH acquisitions were relatively insensitive to the image processing parameters explored. We show that ST analysis of FLASH is a useful and accurate tool in the measurement of cardiac microstructure. While both FLASH and the DTI approaches appear promising for mapping of the alignments of myocytes throughout myocardium, marked discrepancies between the cross myocyte anisotropies deduced from each method call for consideration of their respective limitations. The online version of this article (doi:10.1186/s12968-015-0129-x) contains supplementary material, which is available to authorized users.
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DOI：
10.1196/annals.1341.026
发表时间：
2005-01-01
期刊：
COMMUNICATIVE CARDIAC CELL
影响因子：
--
作者：
Helm, P;Beg, MF;Winslow, RL
通讯作者：
Winslow, RL
影响因子：
3.3
作者：
Beg, MF;Helm, PA;Winslow, RL
通讯作者：
Winslow, RL
影响因子：
5.5
作者：
Bishop, Martin J.;Plank, Gernot
通讯作者：
Plank, Gernot
DOI：
10.1098/rspa.1953.0064
发表时间：
1953-01-01
影响因子：
--
作者：
FISHER, R
通讯作者：
FISHER, R
影响因子：
20.1
作者：
Hooks, Darren A.;Trew, Mark L.;Smaill, Bruce H.
通讯作者：
Smaill, Bruce H.