Purpose

The head circumference is typically used as a surrogate parameter for the development of the central nervous system and intracranial structures and is an important clinical parameter in neuropediatrics. As magnetic resonance images (MRI) can be freely zoomed, visual analysis of the head size often relies on impressions, such as the craniofacial ratio or a simplified gyral pattern. Aim of this study was to validate an MRI-based method to measure the head circumference.

Methods

Head circumferences of 85 children (41 microcephalies, 22 macrocephalies and 22 normal controls; 47 male, mean age 3.22 ± 2.45 years, range 0.19–10.42 years) were retrospectively measured using sagittal 3D-T1w (MPRAGE) data sets. Three readers independently placed an ovoid region of interest in an axial plane starting from the supraorbital bulge and covering the largest supra-auricular head circumference. Clinical measurements of the head circumference taken within an acceptable period served for comparative purposes. Reliability was assessed by calculating the total error of measurement (TEM) and the intraclass correlation coefficient (ICC).

Results

A close correlation was found between MRI-based and clinical measurements. The interrater reliability was excellent (ICC 0.985, 95% confidence interval 0.952–0.993). Absolute TEM ranged from 0.47–0.75, resulting in relative TEM ranging from 1.0–1.6%. Thus, TEMs were classified as acceptable. The mean accuracy of MRI-based measurements was high at 0.94.

Conclusion

The head circumference can be reliably determined with a simple measurement on 3D sequences using multiplanar reformations. This approach may help to diagnose microcephaly and macrocephaly, especially when the head circumference is not reported by the referring physician.

中文翻译：

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测量儿童 MRI 的头围：一项评估者间研究

目的

头围通常用作中枢神经系统和颅内结构发育的替代参数，是神经儿科的重要临床参数。由于磁共振图像 (MRI) 可以自由缩放，因此对头部大小的视觉分析通常依赖于印象，例如颅面比率或简化的回旋模式。本研究的目的是验证基于 MRI 的头围测量方法。

方法

使用矢状 3D-T1w (MPRAGE) 数据集对 85 名儿童（41 名小头畸形、22 名大头畸形和 22 名正常对照；47 名男性，平均年龄 3.22 ± 2.45 岁，范围 0.19-10.42 岁）的头围进行了回顾性测量。三个读者独立地将一个卵形感兴趣区域放置在从眶上隆起开始并覆盖最大耳上头围的轴向平面中。在可接受的时间内进行的头围临床测量用于比较目的。通过计算测量的总误差 (TEM) 和组内相关系数 (ICC) 来评估可靠性。

结果

在基于 MRI 的测量和临床测量之间发现了密切的相关性。评估者间的可靠性非常好（ICC 0.985，95% 置信区间 0.952-0.993）。绝对 TEM 范围为 0.47–0.75，导致相对 TEM 范围为 1.0–1.6%。因此，TEM 被归类为可接受的。基于 MRI 的测量的平均准确度高达 0.94。

结论

使用多平面重构对 3D 序列进行简单测量，即可可靠地确定头围。这种方法可能有助于诊断小头畸形和大头畸形，特别是当转诊医生没有报告头围时。