MRI evaluation and measurement of the normal odontoid peg position

Clinical Radiology, 2009

To evaluate the mean distance from the odontoid process of C2 to the standard skull-base lines (Chamberlain's, McGregor's, and McRae's lines) on computed tomography (CT) imaging. To compare these measurements to previously documented plain radiograph and magnetic resonance imaging (MRI) measurements.Reformatted midline sagittal CT images of 150 adults were retrospectively evaluated. The shortest perpendicular distance was measured from the Chamberlain's, McGregor's and McRae's baselines for each subject to the odontoid tip. Statistical analysis was performed to compare the CT data with the previously obtained MRI and plain film data.The mean position of the odontoid process was 1.4 mm below Chamberlain's line (median 1.2 mm, SD 2.4 mm), 0.8 mm (median 0.9 mm, SD 3 mm) below McGregor's line and 5 mm (median 5 mm, SD 1.8 mm) below McRae's line. There is no significant difference between male and female results (p > 0.05) or between these CT and previous MRI measurements (p > 0.05).These results provide the mean and range of normal distance from the odontoid process to the most frequently used skull-base lines on the current population on CT.

Journal of Neurosurgery: Spine, 2014

2012

European Spine Journal, 2009

Anterior odontoid screw fixation is a safe and effective method for treatment of odontoid fractures. The screw treads should fit into the odontoid medulla, should pass the fracture line, and should pull fractured odontoid tip against body of axis in order to achieve optimum screw placement and treatment. This study has demonstrated optimal anterior odontoid screw thickness, length, and optimal angle for safe and strong anterior odontoid screw placement. Dry bone axis vertebrae were evaluated by direct measurements, X-ray measurements, and computerized tomography (CT) measurements. The screw thickness (inner diameter of the odontoid) was measured as well as screw length (distance between anterior-inferior point body of axis and tip of odontoid), and screw angle (the angle between basis of axis and tip of odontoid). The inner diameter of odontoid bone was measured as 6.5 ± 1.9 mm, the screw length was 37.6 ± 3.3 mm, and the screw angle was 62.4 ± 4.7 on CT. There was no statistical difference between X-ray and CT in the measurements of screw thickness and angle. X-ray and CT measurements are both safe methods to determine the inner odontoid diameter and angle preoperatively. Screw length should be measured on CT only. To provide safe and strong anterior odontoid screw fixation, screw thickness, length, and angle should be known preoperatively, and these can be measured on X-ray and CT.

Journal of Contemporary Orthodontics, 2023

Most of the several cephalometric analyses used for the diagnosis of sagittal dysplasia, Point A is the most widely used indicator for ascertaining of maxillary position. By the virtue of difficulty in locating point A in many cases, alternative methods had been proposed for precise location of point A but there are only few studies on the reliability of these alternative points. Point M is one such indicator for evaluating the sagittal position of maxilla. The objective of this study is to measure and compare the reliability of point A and point M. Materials and Methods: Lateral cephalogram of 50 subjects (11-20 years) were included in the study consisting of all types of skeletal malocclusions. Point A and point M were identified by two different group of orthodontists. Linear and angular measurements through both the points were analysed and compared between the observers using interclass correlation. Results: Interclass correlation coefficient of linear and angular parameters of point M was found to be higher than point A. Conclusion: Point M may be considered as more reliable alternative for point A in two dimensional cephalometric analysis. This is an Open Access (OA) journal, and articles are distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International, which allows others to remix, and build upon the work noncommercially, as long as appropriate credit is given and the new creations are licensed under the identical terms.

World Journal of Dentistry, 2023

Aim: The objective of this investigation was to quantify the relation between the anterior cranial base and the palatal plane [PP-sella-nasion (SN)] in subjects having different sagittal skeletal relationships. Materials and methods: Pretreatment cephalometric radiographs of 106 subjects were obtained. The cephalograms were then traced using the Facad software. The β angle measurement was done to evaluate the sagittal skeletal relationship of the subject. The cephalograms were then grouped into three based on the β angle measurements—groups I, II, and III. The angle formed by the palatal plane (PP) and cranial base intersecting was then measured and tabulated. The data was statistically evaluated using International Business Machines (IBM) Statistical Package for the Social Sciences (SPSS) software. Results: The tabulated data was distributed normally. The overall mean angle between the PP and the cranial base of the included participants was 6.34° ± 4.51°. The difference in the PP-SN angle between groups was not statistically significant. There was no gender disparity observed. Conclusion: Although individual variability exists, the difference in PP-SN angle among the groups and between both genders was not significant statistically (p > 0.05). Clinical significance: The role of the PP-SN angle as a diagnostic and prognostic tool in the management of malocclusion has to be explored further. Quantification of the PP-SN angle for the South Indian population is a first step in this direction. With the rising popularity of the use of temporary anchorage devices (TADs) and orthognathic surgical interventions, the PP-SN angle could be a key determinant factor in the selection of either. Keywords: Angular Relationship, Cephalometry, Sagittal skeletal relationship, Sella-nasion plane.

Musculoskeletal Science and Practice, 2019

Background: Photogrammetric measures are a commonly applied, highly reliable tool for appraising craniovertebral postures during clinical assessments, rehabilitation, and research interventions. Objective: This study aimed to compare and contrast three external measures of postural alignment (EMPA) using photogrammetric and radiological approaches, and to discuss whether the craniovertebral angle (CVA) reflects the shape of the underlying cervical spine. Design: Cross Sectional Correlation Study. Method: Young adults attended three assessment sessions (S1, S2 and S3). S1 involved a standardised photogrammetric protocol. S2 involved radiographic image acquisition. S3 followed the same protocol in S1 but excluded the self-balancing procedure. Each sessions EMPA were compared through either paired or independent samples t-tests. The different radiographic cervical subtypes and their corresponding CVAs were assessed. Results: There were no significant differences in any EMPA between the two photogrammetric sessions. The CVA was the only EMPA to show a significant difference between photogrammetric (S3) and radiographic approaches. Cervical subtype variability is present throughout the full CVA range. Conclusions: Despite the statistically significant difference in the CVA between approaches, the mean difference was small and unlikely to be clinically meaningful. Accordingly, the quantification of EMPA can be undertaken with high levels of precision and reliability using standardised photogrammetric procedures. The CVA, however, does not provide an indication of the shape of the underlying cervical spine. The distinct radiological differences in the inter-segmental orientation of each vertebral motion segment in conjunction with the differences in the overall global cervical alignment, both within and between participants, negate this possibility.

European Spine Journal, 2011

Introduction Odontoid diameter in some individuals may not be large enough to accommodate two 3.5-mm cortical screws for anterior odontoid fracture fixation. The study was performed to evaluate, in a Brazilian population, the diameter of the odontoid process and the feasibility of using two 3.5-mm cortical screws for anterior odontoid fracture fixation. Materials and methods Computed tomographic (CT) scans of 88 adult patients (aged 18-78 years) were analyzed; 40 patients (45%) were male (mean age: 43.08 years) and 48 (55%) were female (mean age: 43.39 years). The minimum external and internal anteroposterior and transverse diameters of the odontoid process on sagittal and coronal planes were measured on CT multiplanar reconstructions of the cervical spine. Results The mean value of the minimum external anteroposterior diameter was 10.83 ± 1.08 and 7.53 ± 1.10 mm for the minimum internal anteroposterior diameter. The mean value of the minimum external transverse diameter was 9.19 ± 0.91 and 6.07 ± 1.08 mm for the minimum internal transverse diameter. The mean AP diameter was significantly larger than the mean transverse diameter; 57 (65%) individuals had the minimum external transverse diameter [9.0 mm that would allow the insertion of two 3.5-mm cortical screws with tapping, and five (6%) individuals had the minimum internal transverse diameter [8.0 mm that would allow the insertion of two 3.5-mm cortical screws without tapping. Conclusions The insertion of two 3.5-mm cortical screws was possible for anterior fixation of odontoid fracture in 57 (65%) individuals of our study, and there was no statistical difference between males and females.

Indian Journal of Radiology and Imaging, 2016

Odontoid process is the central pillar of the craniovertebral junction. Imaging of this small structure continues to be a challenge for the radiologists due to complex bony and ligamentous anatomy. A wide range of developmental and acquired abnormalities of odontoid have been identified. Their accurate radiologic evaluation is important as different lesions have markedly different clinical course, patient management, and prognosis. This article seeks to provide knowledge for interpreting appearances of odontoid on computed tomography (CT) and magnetic resonance imaging (MRI) with respect to various disease processes, along with providing a quick review of the embryology and relevant anatomy.

Clinical spine surgery, 2018

A cross-sectional study. To identify the best indicator for reproducible representation of craniocervical sagittal balance (CCSB). Spinal sagittal balance is considered one of the most critical factors affecting the health-related quality of life. Although standard indicators of spinopelvic balance have been established, these do not include the craniocervical balance and there is no standard parameter for evaluating the CCSB. Six kinds of sagittal vertical axis (SVA) were drawn by a total of 9 spine or orthopedic surgeons, from the anterior margin of the external auditory canal: cranial center of gravity (CCG), C1 (center of the anterior arch), C2 (C2vb: center of the vertebral body, C2e: center of the lower endplate), and C7 (C7vb: center of the vertebral body, C7p: posterosuperior corner). Eight SVA distances were measured by using 30 radiographs; CCG-C7vb, C1-C7vb, C2e-C7vb, C2vb-C7vb, CCG-C7p, C1-C7p, C2e-C7p, and C2bv-C7p.The interobserver and intraobserver reliabilities, and ...