Di Biase Saide, Trignani Marianna, Caravatta Luciana, Voicu Paul Ioan, Di Carlo Clelia, Vinciguerra Annamaria, Augurio Antonietta, Perrotti Francesca, Panara Valentina, Genovesi Domenico
Department of Radiotherapy, "SS Annunziata" Hospital, "G. D'Annunzio" University, Chieti, Italy.
Section of Diagnostic Imaging and Therapy, Radiology Division, Department of Neuroscience and Imaging, "SS Annunziata" Hospital, "G. D'Annunzio" University, Chieti, Italy.
Radiol Med. 2017 Sep;122(9):683-689. doi: 10.1007/s11547-017-0775-1. Epub 2017 May 16.
Irradiation of the hippocampus plays a role in neurocognitive toxicity. Its delineation is complex and in practice different head position can vary hippocampus morphology on axial images; so atlas in a single standard position can result ineffective to describe different hippocampal morphologies in different head set-up. The purpose of our study was to develop a guide based on magnetic resonance imaging for hippocampus delineation in three different head set-ups.
Three patients were selected to elaborate our guide. Patients were submitted to a planning computed tomography of the brain district in different head positions: 1° patient in neutral, 2° patient in over-extended and 3° patient in head hypo-extended position; axial images of 2-mm thickness were obtained. Computed tomography images were fused with diagnostic brain magnetic resonance images; then hippocampus was delineated according to RTOG atlas. Contours were revised by two neuro-radiologists with >5-year expertise in neuroimaging.
A guide was developed for each of three head positions considered. RTOG atlas provided an easy and reliable guide for hippocampus delineation in neutral position of the head. Discrepancies were observed in cranial and caudal limit in case of head over/hypo-extension, as well as in hippocampal morphology near the encephalic trunk where hippocampus takes an oblong shape in over-extended set-up, and short and stocky in hypo-extension.
Our guide can represent a useful tool for hippocampal delineation in clinical practice and for different anatomic variations due to different head positions. Certainly, it should be validated in practice.
海马体的照射在神经认知毒性中起作用。其轮廓描绘复杂，在实际操作中，不同的头部位置会使轴向图像上的海马体形态有所不同；因此，单一标准位置的图谱可能无法有效描述不同头部姿势下的海马体不同形态。我们研究的目的是开发一种基于磁共振成像的指南，用于在三种不同头部姿势下描绘海马体。
选择三名患者来完善我们的指南。让患者在不同头部位置接受脑区的计划计算机断层扫描：第一名患者头部处于中立位，第二名患者头部过度伸展，第三名患者头部伸展不足；获取厚度为2毫米的轴向图像。将计算机断层扫描图像与脑部诊断磁共振图像融合；然后根据放射治疗肿瘤学组（RTOG）图谱描绘海马体。由两名具有超过5年神经影像专业经验的神经放射科医生对轮廓进行修订。
针对所考虑的三种头部位置分别制定了指南。RTOG图谱为头部中立位时的海马体描绘提供了简单可靠的指南。在头部过度伸展/伸展不足的情况下，在颅侧和尾侧界限以及靠近脑干处的海马体形态方面观察到差异，在过度伸展姿势下海马体呈椭圆形，在伸展不足时则短而粗壮。
我们的指南可成为临床实践中描绘海马体以及针对因不同头部位置导致的不同解剖变异的有用工具。当然，它应在实践中得到验证。
