Fujii Shinya, Nagaishi Junichi, Mukuda Naoko, Kaneda Sachi, Inoue Chie, Fukunaga Takeru, Ogawa Toshihide
Division of Radiology, Department of Pathophysiological and Therapeutic Science, Faculty of Medicine, Tottori University.
Department of Pediatrics, Tottori Municipal Hospital.
Magn Reson Med Sci. 2017 Jul 10;16(3):203-208. doi: 10.2463/mrms.mp.2015-0157. Epub 2016 Dec 26.
The characteristics of fetal thyroid on magnetic resonance (MR) imaging, including normal thyroid and disorders other than goiter have not been fully evaluated. Our aim was to assess fetal thyroid using three dimensional (3D) gradient echo (GRE) T-weighted MR imaging and to examine the usefulness of this modality.
The study included 27 3D GRE T-weighted images from 26 fetuses. The largest possible region of interest (ROI) within the thyroid at the slice level depicting the thyroid was manually defined and three circular ROIs on neck muscle were manually defined on the image slices showing the highest signal intensity (SI) of the thyroid. Maximum and mean thyroid-to-muscle SI ratios (SIRs) were then calculated as SIR = maximum or mean thyroid SI/muscle SI.
The thyroid could not be identified in two cases. Fetal thyroid function was normal in 17 cases, and there were 7 cases of hypothyroidism (6 transient and 1 thyroid dysgenesis). There was no linear relationship between mean and maximum SIR and gestational age. The mean and maximum SIR in the cases of normal fetal thyroid were 1.85 ± 0.20 and 2.61 ± 0.39, and the mean and maximum SIR in fetal hypothyroidism were 1.58 ± 0.20 and 2.13 ± 0.37. Mean (P = 0.0088) and maximum (P = 0.0221) SIR values were significantly different between euthyroid and hypothyroid fetuses.
Thyroid SIR measurement provided useful information regarding fetal thyroid function.
胎儿甲状腺在磁共振成像（MR）中的特征，包括正常甲状腺及除甲状腺肿以外的疾病，尚未得到充分评估。我们的目的是使用三维（3D）梯度回波（GRE）T加权MR成像评估胎儿甲状腺，并检验这种方法的实用性。
本研究纳入了26例胎儿的27幅3D GRE T加权图像。在描绘甲状腺的层面手动定义甲状腺内最大可能的感兴趣区（ROI），并在显示甲状腺最高信号强度（SI）的图像层面上手动在颈部肌肉上定义三个圆形ROI。然后计算甲状腺与肌肉的最大和平均SI比值（SIR），公式为SIR = 最大或平均甲状腺SI/肌肉SI。
2例未识别出甲状腺。17例胎儿甲状腺功能正常，7例甲状腺功能减退（6例为暂时性，1例为甲状腺发育不全）。平均和最大SIR与胎龄之间无线性关系。正常胎儿甲状腺的平均和最大SIR分别为1.85±0.20和2.61±0.39，甲状腺功能减退胎儿的平均和最大SIR分别为1.58±0.20和2.13±0.37。甲状腺功能正常和减退的胎儿之间，平均（P = 0.0088）和最大（P = 0.0221）SIR值有显著差异。
甲状腺SIR测量为胎儿甲状腺功能提供了有用信息。
