Imageo-anatomic Research Of Craniocervical Junction

PartⅠ:Gross and Sectional Anatomy Research of Craniocervical JunctionObjective:To know of important structures of craniocervical junction(CCJ) and their adjoins,and further study the sectional anatomy of the important structures in CCJ so as to provide an anatomic reference for image research in this region.Materials and Methods:Twelve formalin fixed specimens including head and neck were utilized(9men,3women,ranged in age from 47 to 73 years old,mean age 67.8 years).Among the total,three specimens were dissected as gross anatomy,three specimens were made into frozen sections(section thickness 5.0mm),the others were used for thin sections(section thickness 0.5mm).Observing morphous of important structures of CCJ and their adjoins.Results:CCJ located in the space which was surrounded by occipital bone, mastoid,petrosal bone,atlas and axis,in addition to some important ligaments(such as the alar ligament,the cruciate ligament,the apical ligament,the anterior atlantooccipital membrane,the posterior atlantooccipital membrane and the tectorial membrane),nerves and blood vessels went through this region.The ligaments in CCJ were observed in order from front to rear,including the posterior atlantooccipital membrane,the tectorial membrane,the cruciate ligament(including the superior and inferior longitudinal fasciculus as well as the transverse ligament),the alar ligament, the apical ligament and the anterior atlantooccipital membrane.The tectorial membrane,the superior longitudinal fasciculus and the apical ligament were adhered tightly to the basilar part of occipital bone,they were very difficult to be separated. Bilateral vertebral arteries were closely related to the first and the second cervical nerve.Conclusions:The gross anatomy and thin section specimens could clearly demonstrate the important structures and their adjoins in CCJ.They could provide an anatomic fundament for further imaging research in this region.PartⅡ:CT and MRI Imageo-anatomic Research of Craniocervical JunctionObjective:To analyze CT and MRI manifestations of important structures of CCJ,and to optimize the examination methods in this region so as to provide a valuable imageo- anatomy fundament for clinical diagnosis.Materials and Methods:Between Oct.2006 and May.2007,51 normal patients aged 34 to 60 years(31men,20 women,mean age 49.4 years) were randomly selected from those who had been performed pre- and post-contrast CT scan in our hospital.For post-contrast CT scan,the patients were injected 100ml of non-ionic contrast agent(350mg I/ml)through ulnar vein at a flow rate of 4.0ml/sec.Images were obtained with transverse plane,and reconstructed with sagittal and conoral plane. 51 normal volunteers who ranged in age from 20 to 39 years old(30men,21women, mean age 27.3 years) and had no cervical injury or complaint were enrolled in the study,multiple pulse sequences of MRI including transverse,coronal and sagittal plane were performed on these patients.By combining gross and sectional anatomy, CT and MRI manifestations of important structures in CCJ were analyzed.Comparing the display of the main ligaments in CCJ(such as the posterior atlantooccipital membrane - dura complex,tectorial ligament - dura complex,transverse ligament,alar ligament and the anterior atlantooccipital membrane) among the multiple pulse sequences of MRI.Measuring the important image anatomic parameters in this region.Results:CT and MRI were sensitive to depict important structures and their adjoins in CCJ.The posterior atlantooccipital membrane - dura complex,tectorial ligament - dura complex,transverse ligament and alar ligament could be demonstrated clearly by CT and MRI,the display rate was 100%respectively(51/51).The apical ligament only may be identified on sagittal plane,the display rate was 29.4%(51/51) by CT and 43.1%(22/51) by MRI.The display rate of the anterior atlantooccipital membrane was 100%(51/51) by MRI.,while it was difficult to be discerned by CT. Two experienced radiologists independently analyzed the main ligaments with every MRI pulse sequence.The results manifested that proton density weighted imaging (PDWI) is the optimal sequence for demonstrating the ligaments in CCJ.There were no significant differences among the basilar angle,the atlantooccipital angle,the basion-dens interval,the position of odontoid process,and the interval difference between bilateral atlas and den(P＞0.05) by comparing the measurement values with CT and MRI.Conclusions:CT and MR imaging may well demonstrate the important structures and their adjoins in CCJ.PDWI was sensitive to manifest the main ligaments in CCJ and it may be recommended as optimal MRI routine sequence for the ligaments.The correct imaging plane could contribute to the demonstration of ligaments in CCJ.Important imageo-anatomic measurement would be beneficial for the diagnosis in this region.