Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands.
Neuroimage. 2012 Jul 16;61(4):1043-9. doi: 10.1016/j.neuroimage.2012.03.023. Epub 2012 Mar 14.
Animal and human autopsy studies suggest that subfields of the hippocampal formation are differentially affected by neuropsychiatric diseases. Therefore, subfield volumes may be more sensitive to effects of disease processes. The few human studies that segmented subfields of the hippocampal formation in vivo either assessed the subfields only in the body of the hippocampus, assessed only three subfields, or did not take the differential angulation of the head of the hippocampus into account. We developed a protocol using 7 Tesla MRI with isotropic voxels to reliably delineate the entorhinal cortex (ERC), subiculum (SUB), CA1, CA2, CA3, dentate gyrus (DG)&CA4 along the full-length of the hippocampus. Fourteen subjects (aged 54-74 years, 2 men and 12 women) were scanned with a 3D turbo spin echo (TSE) sequence with isotropic voxels of 0.7 × 0.7 × 0.7 mm(3) on a 7 T MRI whole body scanner. Based on previous protocols and extensive anatomic atlases, a new protocol for segmentation of subfields of the hippocampal formation was formulated. ERC, SUB, CA1, CA2, CA3 and DG&CA4 were manually segmented twice by one rater from coronal MR images. Good-to-excellent consistency was found for all subfields (Intraclass Correlation Coefficient's (ICC) varying from 0.74 to 0.98). Accuracy as measured with the Dice Similarity Index (DSI) was above 0.82 for all subfields, with the exception of the smaller subfield CA3 (0.68-0.70). In conclusion, this study shows that it is possible to delineate the main subfields of the hippocampal formation along its full-length in vivo at 7 T MRI. Our data give evidence that this can be done in a reliable manner. Segmentation of subfields in the full-length of the hippocampus may bolster the study of the etiology neuropsychiatric diseases.
动物和人体解剖研究表明，海马结构的亚区受神经精神疾病的影响程度不同。因此，亚区体积可能对疾病过程的影响更为敏感。少数在体内对海马结构的亚区进行分割的人体研究，要么仅在海马体的主体部分评估亚区，要么仅评估三个亚区，要么没有考虑到海马头部的不同角度。我们开发了一种使用 7T MRI 进行各向同性体素成像的协议，以可靠地区分沿整个海马全长的内嗅皮层（ERC）、下托（SUB）、CA1、CA2、CA3、齿状回（DG）和 CA4。14 名受试者（年龄 54-74 岁，2 名男性和 12 名女性）在 7T 全身 MRI 扫描仪上使用三维涡轮自旋回波（TSE）序列进行扫描，体素为 0.7×0.7×0.7mm(3)。基于先前的协议和广泛的解剖图谱，制定了一个新的海马结构亚区分割协议。ERC、SUB、CA1、CA2、CA3 和 DG&CA4 由一位评分者从冠状 MR 图像中手动分割两次。所有亚区的一致性都很好到优秀（内类相关系数（ICC）从 0.74 到 0.98 不等）。所有亚区的 Dice 相似性指数（DSI）测量的准确性均高于 0.82，除了较小的 CA3 亚区（0.68-0.70）。总之，本研究表明，在 7T MRI 上可以在体内沿整个海马全长描绘出海马结构的主要亚区。我们的数据证明这是可以可靠完成的。在海马全长范围内对亚区进行分割，可能会加强对神经精神疾病病因的研究。
