The Study Of Sectional And Imaging Anatomy Of The Cistern Of Pontocerebellar Trigone Region And Its Three-dimentional Reconstruction

Pontocerebellar trigone is the main pathogenetic site of intracranial tumor and the most frequent type is the acoustic neuroma.It is also the main pathogenetic site of unilateral facial convulsion,trigeminal neuralgia,and vestibulocochlear vasoneurocompreasion.Because the adjacent structures are complicated and in large quantity,it offers a challenge to diagnose and treat the diseases in this area.With the rapid development of imaging techniques,the knowledge about sectional anatomy hadn't met the needs of the clinic,therefore the knowledge about thin sectional anatomy would be needed to explore.As the gradually generalization and application of endoscopic surgery clinically,preoperative evaluation appeared especially significant,but the reports about which hadn't appeared.This study combined thin sectional planes of two brains and corresponding MR images for control study,and the models of PCTR.with three-dimensional visualization will be reconstructed, hoping to provide anatomical data for image diagnosis and preoperative evaluation.The study was divided into three parts.The abstracts were as follows:Part 1:Study of the correlation between cross-sectional anatomy and MRI in pontocerebellar trigone Purpose:To provide anatomical data for image diagnosis and preoperative evaluation about diseases in PCTR.Methods:One head specimen of Chinese adult was selected and scanned by 1.5T MRI with routine technology,then embedded with gelatin and frozen under profound hypothermia.Subsequently,the specimen was sliced into 0.1mm transverse serial sections along AC-PC line with SK500 computerized freezing milling machine at -15℃in a hypothermal temperature laboratory.The slices of the pontocerebellar trigone region were as thin as 0.05mm.Then the serial sections were photographed with high-resolution digital camera and saved in computer.The microstructures of PCTR were observed and measured on typical cross sections of cadaver head and MRI.Results:The 240 transverse sections involving with PCTR were obtained. Comparing the MRI with thin sectional images,we investigated the sectional anatomy of the PCTR.(1) The anatomy of the PCTR could be observed clearly on the successive thin sections.The anterior inferior cerebellar artery originated from the basilar artery on the transverse section through internal carotid artery and extended to the internal auditory foramen along with the facial nerve,then ran between the facial nerve and the vestibulocochlear nerve to the cerebellum.(2) The length of the pontocerebellar trigone segment of facial nerve could be demonstrated on the section through pontocerebellar trigone.(3) The posterior lip of internal auditory foramen was the highest on the transverse section through internal auditory foramen,and the height of the posterior lip of internal auditory foramen of two sides were all less than the one third of the longitude of the facial nerves ipsilaterally in the pontine cistern.Conclusions:Combination of transverse slices obtained from digital freezing milling technique and magnetic resonance images offered a better understanding of the complex anatomic structures and provided anatomical data for imaging diagnosis and evaluation of preoperation. Part 2:Study of the correlation between coronal sectional anatomy and MRI in pontocerebellar trigonePurpose:To provide coronal anatomical data for image diagnosis and preoperative evaluation about diseases in PCTR.Methods:One fresh head specimen of chinese adult was selected and scanned by 1.5T MRI with routine technology,then embedded with colored gelatine(red for artery and blue for vein) and frozen under profound hypothermia.Subsequently,the specimen was sliced into 0.1mm transverse serial sections along the vertical line of AC-PC line with SK500 computerized freezing milling machine at -15℃in a hypothermal temperature laboratory.The slices of the pontocerebellar trigone region were as thin as 0.05mm.Then the serial sections were photographed with high-resolution digital camera and saved in computer.The microstructures of pontocerebellar trigone region were observed and measured on typical cross sections of cadaver head and MRI.Results:From anterior to posterior,in other words,from the origin of anterior inferior cerebellar artery to the emergence of jugular fossa,180 coronal planes of PCTR were acquired.(1) It was the best section to display the part of facial nerve through cisterna pontis in the coronal section through the facial nerve stem,which could retrieve the deficient of cross section.(2) The adjacent structures could be traced along the approach of endoscopic surgery in coronal section.As a result,the coronal section could provide anatomic data to diagnose and discriminate the structures in this area.Conclusions:Combination of slices obtained from digital freezing milling technique and magnetic resonance images could precisely display the whole part of facial nerve through cisterna pontis and direct the approach of endoscopic surgery.So the study could provide anatomic data to diagnosis and preoperative evaluation in this area. Part 3:The three-dimensional reconstruction of pontocerebellar trigonePurpose:To satisfy the MRI requirement of diagnosis and evaluation of micro-wounds treatment for acoustic neuroma and nerve and vascular compression. Methods:The three-dimensional visualization was accomplished using the 0.05mm transverse serial sections with SK500 computerized freezing milling machine.Then the reconstituted models were used to research the spatial relationship of main anatomic structures in PCTR.Results:The three-dimensional visual models of the pontocerebellar trigone area could be dimonstrated the spatial relationship of nerves and vessels all the angles and all the directions,and could be observed the sectional anatomy of the PCTR directly.Conclusions:The reconstructed models with three-dimensional visualization could display the spatial relationship of nerves and vessels as well the distributed rules and morphous of adjacent structures in this area.So they could provide all round anatomic data for imaging study and clinical application about PCTR.It has been proved that three-dimensional reconstruction was an effective and intuitionistic method to study the structures in PCTR.Conclusion and SignificanceCombination of transverse slices obtained from digital freezing milling technique and magnetic resonance images offered a better understanding of the complex anatomic structures;Combination of slices obtained from digital freezing milling technique and magnetic resonance images could precisely display the whole part of facial nerve through cisterna pontis and direct the approach of endoscopic surgery;The reconstructed models with three-dimensional visualization could display the spatial relationship of nerves and vessels as well the distributed rules and morphous of adjacent structures in this area.So they could provide all round anatomic data for imaging study and clinical application about PCTR.It has been proved that three-dimensional reconstruction was an effective and intuitionistic method to study the structures in PCTR.