Three-dimensional Segmentation Of Hippocampal Formation With Magnetic Resonace Imaging And The Value In Lateralization Of Refractory Temporal Lobe Epilepsy

There were two parts in this paper:Ⅰ.Identification of normal hippocampal formation with MRI;Ⅱ.Three-dimensional segmentation of hippocampal formation with magnetic resonace imaging(MRI) and the value of volumetric analysis in lateralization of refractory tepmoral lobe epilepsy The first part was the basis of the second one.Part Ⅰ: Identification of normal hippocampal formation with magnetic resonace imaging(MRI)Objective:To identify the normal anatomy of hippocampal formation(HF) and its adjacent structures,provide sectional anatomic data for segmentation of HF with MRI.To determine the occurrence of anterior and posterior boundary in different MRI planes,provide basis of software for HF segmentation.Methods: 1.Sujects and MRI acqusition.Thirty-one healthy young adults and two adult cadaveric human brain specimens were employed for this study. For healthy controls,the T1 volumes were acquired using a three-dimensional spoiled gradient echo acquisition (SPGR)with sagittal volume excitation All images were transferred to a workstation (SUN) and processing of the MRI data was performed with a three-dimensional software package-Volume Analysis produced by GE company.Tilted coronal images (perpendicular to main part of right HF),corresponding sagittal imgaes were yielded with 1.5mm thickness.For cadaveric brains,the coronal and sagittal sections were obtained in correspondence with MR images with 3mm thickness. 2.Labelling HF.Observed the features of HF,and selected one of 31 healthy contorls in random.The tilted coronal and sagittal images were correlated with the anatomic sections to determine the MR appearance of the individual structures with reference to the anatomic atlases,articles and guided by the neuroanatomist.3．Identified the HF with three-dimensional volumetric software.Observed the anterior and posterior boundaries of bilateral HFs of 31 healthy controls,compared the occurrence rates in tilted coronal and sagittal sections.Results:1.Described the componants of HF and the related structures in anatomic and MRI sections,and the corresponding MRI signal features in details. 2.About the boundaries, 29.03 percent of right hippocampal head(HH), 41.94 percent of left HH, 64.52 percent of right hippocampal tail(HT), 54.84 percent of left hippocampal tail(HT) could't be showed on tilted coronal planes fully; 6.45 percents of right HH, 9.68 percent of left HH , 3.23 percent of right HT, 3.23 percent of HT could't be seen completely.The display rates of HH and HT boundaries between the coronal and sagittal planes were different significantly(P<0.05).These differences had nothing to do with right or left hemispheres (P>.05)and sex of the normal volunteers(P>0.05),except for left HT in coronal sections(P<0.05).The display rates between anterior and posterior boundary in the coronal or sagittal planes were not different significantly, but for left hippocampus in coronal plane.Individual analysis showed that only one left posterior boundary of HF and one right anterior boundary of HF could't be seen clearly.Conclusions:Most parts of hippocampal formations and adjacent structures can be seen on MR images.Although MR images can't show the boundary between the Ammon's horn and dentate gyrus,it defines the outline of major fissures,which can help the reader to infer the location of the cellular anatomy.The display capacity of sagittal palne on MR images is better than that of coronal plane. Most parts of the hippocampus can be segmentated in most of nomal volunteers, combinating coronal and sagittal planes.PartⅡ.Three-dimensional segmentation of hippoca-mpal formation with magnetic resonace imaging(MRI) and the value of volumetric analysis in lateralization of refractory tepmoral lobe epilepsy(TLE)Objective: To establish a semiautomated volumetric method of HF based on three-dimensional software program with excellent accuracy , reliability and high speed of segamentation.And make the HF volumetry on MR images a practical clinical method.To analyze the HF volumes of norma...