Isaacs Albert M, Shimony Joshua S, Morales Diego M, Castaneyra-Ruiz Leandro, Hartman Alexis, Cook Madison, Smyser Christopher D, Strahle Jennifer, Smyth Matthew D, Yan Yan, McAllister James P, McKinstry Robert C, Limbrick David D
1Department of Neuroscience, Washington University School of Medicine, St. Louis, Missouri.
2Department of Clinical Neurosciences, University of Calgary, Calgary, Alberta, Canada; and.
J Neurosurg Pediatr. 2019 Jul 19;24(4):461-468. doi: 10.3171/2019.5.PEDS18596. Print 2019 Oct 1.
Traditionally, diffusion MRI (dMRI) has been performed in parallel with high-resolution conventional MRI, which requires long scan times and may require sedation or general anesthesia in infants and young children. Conversely, fast brain MRI permits image acquisition without the need for sedation, although its short pulse sequences, susceptibility to motion artifact, and contrast resolution have limited its use to assessing ventricular size or major structural variations. Here, the authors demonstrate the feasibility of leveraging a 3-direction fast brain MRI protocol to obtain reliable dMRI measures.
Fast brain MRI with 3-direction dMRI was performed in infants and children before and after hydrocephalus treatment. Regions of interest in the posterior limbs of the internal capsules (PLICs) and the genu of the corpus callosum (gCC) were drawn on diffusion-weighted images, and mean diffusivity (MD) data were extracted. Ventricular size was determined by the frontal occipital horn ratio (FOHR). Differences between and within groups pre- and posttreatment, and FOHR-MD correlations were assessed.
Of 40 patients who met inclusion criteria (median age 27.5 months), 15 (37.5%), 17 (42.5%), and 8 (20.0%) had posthemorrhagic hydrocephalus (PHH), congenital hydrocephalus (CH), or no intracranial abnormality (controls), respectively. A hydrocephalus group included both PHH and CH patients. Prior to treatment, the FOHR (p < 0.001) and PLIC MD (p = 0.027) were greater in the hydrocephalus group than in the controls. While the mean gCC MD in the hydrocephalus group (1.10 × 10-3 mm2/sec) was higher than that of the control group (0.98), the difference was not significant (p = 0.135). Following a median follow-up duration of 14 months, decreases in FOHR, PLIC MD, and gCC MD were observed in the hydrocephalus group and were similar to those in the control group (p = 0.107, p = 0.702, and p = 0.169, respectively). There were no correlations identified between FOHR and MDs at either time point.
The utility of fast brain MRI can be extended beyond anatomical assessments to obtain dMRI measures. A reduction in PLIC and gCC MD to levels similar to those of controls was observed within 14 months following shunt surgery for hydrocephalus in PHH and CH infants. Further studies are required to assess the role of fast brain dMRI for assessing clinical outcomes in pediatric hydrocephalus patients.
传统上，扩散加权磁共振成像（dMRI）是与高分辨率传统磁共振成像并行进行的，这需要较长的扫描时间，并且在婴幼儿中可能需要镇静或全身麻醉。相反，快速脑磁共振成像允许在无需镇静的情况下进行图像采集，尽管其短脉冲序列、对运动伪影的敏感性以及对比分辨率限制了其仅用于评估脑室大小或主要结构变异。在此，作者证明了利用三向快速脑磁共振成像方案获得可靠的dMRI测量值的可行性。
对脑积水治疗前后的婴幼儿进行三向dMRI的快速脑磁共振成像检查。在扩散加权图像上绘制内囊后肢（PLIC）和胼胝体膝部（gCC）的感兴趣区域，并提取平均扩散率（MD）数据。通过额枕角比（FOHR）确定脑室大小。评估治疗前后组间和组内差异以及FOHR与MD的相关性。
在40名符合纳入标准的患者（中位年龄27.5个月）中，分别有15名（37.5%）、17名（42.5%）和8名（20.0%）患有出血后脑积水（PHH）、先天性脑积水（CH）或无颅内异常（对照组）。脑积水组包括PHH和CH患者。治疗前，脑积水组的FOHR（p < 0.001）和PLIC MD（p = 0.027）高于对照组。虽然脑积水组的平均gCC MD（1.10×10⁻³ mm²/秒）高于对照组（0.98），但差异不显著（p = 0.135）。中位随访时间为14个月后，脑积水组的FOHR、PLIC MD和gCC MD均下降，且与对照组相似（分别为p = 0.107、p = 0.702和p = 0.169）。在两个时间点均未发现FOHR与MD之间存在相关性。
快速脑磁共振成像的用途可以从解剖学评估扩展到获得dMRI测量值。在PHH和CH婴幼儿脑积水分流手术后14个月内，观察到PLIC和gCC MD降低至与对照组相似的水平。需要进一步研究来评估快速脑dMRI在评估小儿脑积水患者临床结局中的作用。
