McDowell Amy R, Shelmerdine Susan C, Carmichael David W, Arthurs Owen J
1 UCL Great Ormond Street Institute of Child Health , London , UK.
2 Department of Radiology, Great Ormond Street Hospital for Children NHS Foundation Trust , London , UK.
Br J Radiol. 2018 Dec;91(1092):20180319. doi: 10.1259/bjr.20180319. Epub 2018 Aug 30.
: To investigate the potential of advanced diffusion weighted imaging (DWI) in post-mortem MRI (PMMR) at 3T.
: We acquired PMMR brain and body imaging in 12 neonates, mean gestational age 33.4 weeks (range 29-37 weeks) at 3T and 1.5T. Head and body diffusion imaging at 1.5T consisted of bipolar diffusion encoding and single-shot spin-echo echo-planar imaging (SE-EPI) for acquisition (echo time (TE) 96 ms; repetition time (TR) 2700 ms; voxel size 1.8 x 1.8 mm in-plane with slice thickness 5 mm; b-values of 500 and 1000 s/mm applied in three orthogonal directions; total acquisition time 2:12). A whole-body 3T diffusion imaging protocol using monopolar diffusion encoding and simultaneous multislice EPI acquisition with gradients applied in 12 uniformly distributed directions was obtained (TE 53.4 ms; TR 5600 ms; 1.8 mm isotropic; multiband factor 2; b-values of 250, 750, 1250 and 1750 s/mm; acquisition time 2:09 for a single b-value).
: There was significant improvement in image quality in multiband, multislice diffusion PMMR protocol. On visual assessment of image quality, 1.5T DWI scored poorly (mean 2.4 SD ± 0.47), and all 3T b-values individually scored significantly higher (p < 0.001) apart from b = 250 s/mm which was not significantly different.
: Recent advances in diffusion sequences and hardware utilising higher field strengths and gradient performance allows whole-body diffusion PMMR imaging at high resolution with improved image quality compared to the current clinical approach.
: We have demonstrated feasibility of a multislice, multiband quantitative diffusion imaging sequence in the perinatal post-mortem setting. This will allow more detailed and quantitative clinical PMMR investigations using diffusion MRI in the future.
研究3T场强下高级扩散加权成像（DWI）在尸检磁共振成像（PMMR）中的应用潜力。
我们对12例新生儿进行了PMMR脑部和身体成像，这些新生儿的平均胎龄为33.4周（范围29 - 37周），扫描场强为3T和1.5T。1.5T场强下的头部和身体扩散成像采用双极扩散编码和单次激发自旋回波平面回波成像（SE - EPI）进行采集（回波时间（TE）96 ms；重复时间（TR）2700 ms；层面内体素大小为1.8×1.8 mm，层厚5 mm；在三个正交方向上施加的b值为500和1000 s/mm²；总采集时间2:12）。获得了一种全身3T扩散成像方案，该方案采用单极扩散编码和同时多层面EPI采集，梯度在12个均匀分布的方向上施加（TE 53.4 ms；TR 5600 ms；各向同性体素大小1.8 mm；多频段因子2；b值为250、750、1250和1750 s/mm²；单个b值的采集时间为2:09）。
多频段、多层面扩散PMMR方案的图像质量有显著改善。在图像质量的视觉评估中，1.5T DWI评分较低（平均2.4±0.47标准差），除b = 250 s/mm²外，所有3T的b值个体评分均显著更高（p < 0.001），b = 250 s/mm²时无显著差异。
与当前临床方法相比，利用更高场强和梯度性能的扩散序列及硬件的最新进展使得全身扩散PMMR成像能够以高分辨率进行，且图像质量得到改善。
我们已经证明了在围产期尸检环境中多层面、多频段定量扩散成像序列的可行性。这将使未来使用扩散磁共振成像进行更详细和定量的临床PMMR研究成为可能。
