Sectional Anatomy Of Thalamus And Its Reconstruction

ObjectiveThalamus is the biggest part in diencephalon, which is a oval graymatter complex distributing symmetrically on both sides of the thirdventricle, its size is about3cm (sagittal diameter)*1.5cm (transversediameter)*1.5(longitudinal diameter), consisting of many differentfunctional properties of neural nuclei; divided into anterior nucleus, medialnucleus and lateral nucleus by internal Y-shaped inner medullary plate.Thalamus is the largest subcortical receiving station and relay station. Theimpulse from inner and outer body could be accepted by the thalamus afterrelaying and integration, and then projected to the brain cortex, finallygenerating feeling and consciousness. Recently the studys of thalamicfunction are fruitful. However, due to technical limitations, humanthalamus morphological description and volume measurement are limitedon corpses for a long time. With the advances in neuroimaging technology,the thalamus and the structures around the thalamus observing in vivomorphological become possible, which is expected to provide authenticbasis for the diagnosis of certain neuropsychiatric diseases. Thus, based on the specimens of adult head, the author collected magnetic resonanceimages of normal adult thalamus, analyzing normal morphology of thethalamus, so that to acquire the normal adult thalamus morphological dataand provide a unified valuable information.Methods1. Totally30adult head specimens were used for making serial levelsections of which the thickness is5mm and which were parallel toegnthmeatal1ine(CML). The three continuous sections in which thethalamus and the structures around the thalamus could be observed clearlywere studied with the method of sectional anatomy. The data wereprocessed after normalization.2. Analyzing the relationship between the thalamus and the structuresaround the thalamus from magnetic resonance brain images of70healthyadults (35males,35females). Acquiring sequence is3D BRAVO, sequenceparameters: TI450, TR8.4, TE3.2, FOV24.0, NEX1, matrix:224×224，thickness1mm; no interval when scanning successively, scanning rangecovering the whole brain. The images obtained are transferring to theworkstation, adjusted to the best contrast.3.30patients (7males,23females), without significantlyneuropsychiatric disorders in healthy adults, were selected randomly.Scaning with GE3.0T on the line perpendicular to the long axis of thethalamus; acquisition sequence is3D BRAVO; sequence parameters: TR8.4, TE3.2, TI450, matrix:224×224，NEX1, FOV24.0, scanning covers thewhole brain,1mm thickness; no interval between successive scanning. Theimages obtained are transferring to the workstation, adjusting to the bestcontrast. The measurement of the thalamus was done with manualsegmentation and IBASPM.4. The three-dimensional model of the thalamus was established withcollected data by Mimics software.ResultsPart oneCross sectional anatomy and MRI analysis of the thalamusSection one: Cross sectional anatomy of the thalamusAfter normalization, the gender difference and lateral differencebecame marginally significant in the parameters of the thalamus on thecadavers. On the cadavers the length of the thalamus was negatively relatedto the transverse of the putamen. There was a negative relationship betweenthe width of the thalamus and the sagittal of the putamen. The area of thethalamus was negatively related to the area of the caudate nucleus head,and the transverse diameter, the sagittal diameter, the area of the putamenrespectively.Section two: MRI analysis of the thalamusOn MRI scans, the gender difference is significant on the sagittaldiameter and the length of the thalamus; the lateral difference is significant on the transverse diameter and the area of the thalamus. The sagittaldiameter and length of the thalamus was negatively related to the sagittaldiameter of the caudate nucleus head, the sagittal diameter of the putamenand the area of the putamen. There was a positive relationship between thewidth of the thalamus and the sagittal diameter of the caudate nucleus head,the transverse diameter of the putamen, the sagittal diameter of theputamen, the area of the putamen.Section three: volume measurement of the thalamusThe lateral difference is significant on the length and the volume ofthe thalamus when measuring manually. After normalization, the diametersmostly related with the volume of the thalamus are the length of thethalamus and the distance between the anterior horns of lateral ventriclewhen measuring manually. The length of the thalamus is mostly relatedwith the volume of the thalamus after normalization when measuring withIBASPM.Part twoThe reconstruction of the thalamusThe3D model of the thalamus reconstructed successfully based onthe MRI images with Mimics was vivid and could be displayed by differentcolors. It also could be viewed at any directions when amplifying, zoomingout, rotating and so on. ConclusionsThere is a linear relationship between the thalamus and the structuresaround the thalamus, the morphological changes of the structures aroundthe thalamus could be used as reference to the study of the thalamus. Thereconstructed3D model of the thalamus is helpful for anatomy teaching,studying and the clinical diagnosing.