| ObjectiveNowadays, spinal diseases are diversified, and low back pain is one of the major health problems in all countries. At present, many people agreed that the lumbar vertebrae degeneration, such as lumbar intervertebral disc herniation, spinal canal stenosis, lumbar vertebrae instability, can cause acute and chronic injury of the spinal nerve root, and then there is the low back pain at last. In addition, there is the largest load and motion range in lumbar spine. There are many rotation functions, small joints, ligaments, nerve and blood vessels, thus it is damaged easily. However, spinal surgery is still a challenge. It is very important to establish virtual hepatic surgery via CT and MRI anatomy, thin sectional anatomy. We can observe and measure the intervertebral disc and lumbar nerve and find out the puncture path. It is helpful to find the best path for puncture and find out anatomical foundations of puncture complications. Therefore, the main structure of the lumbar spine and the adjacent structure were studied in sectional anatomy and imaging visualization. It is helpful to understand major anatomical structures and relationships of the lumbar spine and helpful to diagnose and treat spinal diseases. It can also provide navigation information for spinal microsurgery. In this study, from the view of clinical application in microsurgery, we observe the morphological regularity of lumbar spine by using comparison between sectional anatomy and multi-slice CT (Multi-slice computed tomography, MSCT). Then we use Materialise's Interactive Medical Image Control System to reconstruct the three-dimensional model of lumbar spine in order to develop further finite element analysis of spine and lay the foundation for virtual surgery.Materials and methods1. Thirty consecutive cross-sectional specimens (male 18, female12) and eight sagittal plane specimens (male 4, female 4) in cadavers were study to observe and measure the records related to lumbar vertebrae. The data were analyzed by using statistical software.2. An analysis of lateral scout CT scans from 100 (male57, female43) consecutive lumbosacral CT examinations (GE, LightSpeed 64-slice spiral CT) was performed. One hundred consecutive patients without diseases, among 35~45 years old, were included in the study. Scan parameters were set as tube voltage 100 ~ 120kV, tube current 250~300mA, tube speed 0.4s/r, pitch 0.531/0.969, matrix 512×512, slice thickness 5mm, reconstruction thickness 0.625mm, reconstruction interval 0.625mm. The lumbar vertebrae were three-dimensional reconstructed by GE ADW 4.2 workstation of CT machine. An analysis was made to observe and measure the related data of lumbar vertebrae and related structures on the sections and the images, and the comparison between tendencies of data on section versus them on image was performed.3. The CT scanning data of lumbar vertebrae were used, two-dimensional images data were collected. The three-dimensional model of lumbar vertebrae was established with collected data by Mimics software. Then, the three-dimensional model of lumbar vertebrae was imported into Ansys software for finite element analysis in order to do virtual hepatic surgery.ResultsThe first part Study of the lumbar spine on Sectional Anatomy and CTIn the study of the lumbar spine on Sectional Anatomy and CT, the results show that for different lumbar vertebrae there is a significant sex difference(P<0.05)for transverse diameter and sagittal diameter of vertebral body, transverse diameter of vertebral canal, spine index, transverse diameter of pedicle of vertebral arch, the length of OE, but not for sagittal diameter of vertebral canal, the angle of Z. There is not a significant difference(P<0.05)for transverse diameter of pedicle of vertebral arch, the length of OE in two sides of lumbar vertebrae, but there is a significant difference neither in sex nor position. Angle of bilateral vertebral plate varies from70°to 90°. All of lumbar spinal indexes are less than 1:4.5. There is a significant sex differenc(eP<0.05)for height of pedicle, anteroposterior diameter of intervertebral foramina and Sagittal diameter of intervertebral foramina, but not for thickness of lamina on CT. The same tendencies were noted in polygrams on cross-sectional specimens and CT scans for measurements of the lumbar vertebrae.On the plane through the upper of the intervertebral disc, sagittal diameters of lateral recess for L3～L5 were (7.43±0.52), (7.34±0.77), (6.78±0.58) mm in cadavers, respectively. NO statistically significant difference was seen in males and females for sagittal diameter of lateral recess, but there is a significant sexual difference for it on CT scans. Sagittal diameters of lateral recess were (7.05±1.19), (6.25±0.94), (6.98±1.30) mm in males, and (7.53±1.37), (7.05±1.14), (7.35±1.39) mm in females, respectively. On cross-sectional specimens and CT scans, there were the same tendencies in polygrams which were drawn by measurements of the records related to lumbar vertebrae. NO statistically significant correlativity was seen between sagittal diameter of lateral recess and thickness of ligamenta flava on cross-sectional specimens and CT scans, but there was a significantly negative correlation with transverse diameter and sagittal diameter of intervertebral disc. The three-dimensional digital models of lumbar vertebrae were reconstructed successfully which were based on the CT and MRI images by Mimics software. The three-dimensional digital models of lumbar vertebrae not only looked veridical and accurate but also could be reconstructed and measured explicitly by CT and MRI lamellate images. The model's pictures were vivid and anatomical structures were limpid. The models can not only be displayed in different colors and combined colors randomly but also be observed at any directions by amplification, zooming down, rotating and so on. The three-dimensional models could be established in BMP or JPEG or AVI video formats, and the videos broadcast were fluent. The three-dimensional digital models could be imported into Ansys software and the finite element models of knee joint and lumbar vertebrae were constructed successfully. The reconstructed three-dimensional finite element models of the knee joint and lumbar vertebrae are helpful for anatomical teaching and studying and it also could be used as the basis for the finite element analysis and virtual hepatic surgery.Conclusions1. The study of lumbar spine was made by the anatomical specimens and three-dimensional reconstruction in 64-MSCTA, both methods have advantages and disadvantages. There are complementary each other. The same tendencies were noted in polygrams on cross-sectional specimens and CT scans for measurements of the lumbar vertebrae. Thus, CT is a reliable method in clinic. It can provide navigation information and guide rational surgery program for doctors.2. The results show that for different lumbar vertebrae there is a significant sex difference for the records related to lumbar vertebrae. The transverse diameter and sagittal diameter of vertebral body, the spine index, the angle of bilateral vertebral plate, as well as the transverse diameter and sagittal diameter of vertebral canal, have the same sensitivity in the evaluation of stenosis. It is vital for using translaminar screw to combine image before an operation.3. Transverse diameter and sagittal diameter of intervertebral disc, thickness of ligamenta flava have the same sensitivity in the evaluation of lateral recess stenosis. It is an important factor for lateral recess stenosis to lead to lumbar spinal stenosis. There were the same tendencies in polygrams on cross-sectional specimens and CT scans for measurements of the records related to lumbar vertebrae, so CT can better reflect the lateral recess and adjacent structures. Pathological changes in adjacent structures may result in the lateral recess stenosis.4. The diagnostic rate of lateral recess stenosis has been increased greatly with the applications of CT and MRI in clinic. Because of the post-processing techniques of spiral CT scan, namely, multi-plane volume reconstruction (MPVR) techniques, CT had more advantages than magnetic resonance imaging (MRI) in the diagnosis of lateral recess. MPVR can select the ideal conditions to reconstruct images which can provide more accurate images for demonstrating lateral recess, and have a consecutive observation of lateral recess. MPVR can use navigational position line to localize exactly, so we can observe and measure the dimension of lateral recess with different window width and window level via different angles, and observe related structures on different planes in different angles, including horizontal plane, sagittal plane and coronal plane. Therefore, we can better comprehend relationships between lumbosacral nerve roots and diseased regions. Namely, it will further improve diagnostic rate of lateral recess stenosis. The spiral CT scans provide smooth and clear three-dimensional models that it would reconstruct spinal structures in order to reveal inherent connections each other, and it also avoided difficulties of direct measurement in cadavers and observation errors produced by deformation. The results also showed that the data tendencies were similar on anatomical sections and CT scans, namely, measured data on CT scans can assess structures of lumbar vertebrae well. In addition, the operation of CT is easy. The amplification ratio used in CT is perpusillous, which provides more accurate values used in diagnose and measurement.5. Mimics software can obtain the data quickly from CT scans and reconstruct the three-dimensional model of lumbar vertebrae, but the division of soft tissue and intervertebral disc was time consuming. The reconstructed three-dimensional finite element models of the lumbar vertebrae are helpful for anatomical teaching and studying and it also could be used as the basis for the finite element analysis and virtual hepatic surgery. |
PDF Full Text Request