Magnetic Resonance Imaging Measurement Of Lines And Angle Correlative Basilar Invagination And It's Clinical Significance

Purpose: To determine the normal ranges of the depth of the anterior and posterior rims of foramen occipital magnum and the angle between medulla oblongata and the upper spinal cord on midsagittal MRI in normal Chinese idividuals and patients with basilar impression,to study their clinical significance and to provide normal reference in diagnosing basilar invagination by MRI. Methods: The depth of the anterior and posterior rims of foramen magnum and the angle between medulla oblongata and upper spinal cord on midsagittal SE or FSE T1WI were measured in 320 normal Chinese individuals and in 36 patients with basilar impression. The normal subjects were divided into 16 groups according to the sex and age,20 subjects each group.MRI data were obtained with a 1.5T MR scanner.t-test was used as statistical significance test for sex difference and analysis of variance for age difference. 95% confidence interval indecates the normal value range . Results: 1. Before 30 years,the depth of the anterior rim of foramen magnum had no obvious statistical sex difference in normal groups (P>0. 05) ,and after 30 years,it had obvious statstical sex difference in normal groups (P<0. 05 ) .There was obvious statstical age difference between 0-9 years group and 10-19 years group and there were no obvious statstical age difference after 10 years . There were very obvious statistical difference between the patients with basilar invagination and normal groups (P<0.01) .It ranged from 34.5267mm to 35.3233mm for normal individuals and 25.9291mm to 27.2709mm for the patients with basilar invagination. There was no overlap between them . 2. Before 30 years ,the depth of the posterior rim of foramen magnum had obvious statistical sex difference in normal idividuals (P<0. 05) and has no obvious statistical sex difference aftef 30 years (P>0. 05) . There were no obvious statistical age difference in normal idividuals .There were no obvious statistical difference between the patients with basilar invaginationand normal groups .It ranged from 32.8316mm to 33.6371mm for normal individuals and 33.1735mm to 35.626 5mm for the patients with basilar invagination. There was overlap between them. 3. Before 60 years, the angle between medulla oblongata and upper spinal cord had no obvious ststistical sex difference in normal idividuals ( P >0. 05) ,and after 60years it had obvious statistical sex difference (P<0. 05) . There was obvious statstical age difference between 0-9 years group and 10-19 years group and there was no obvious statstical age difference after 10 years . There were very obvious statistical difference between the patients with basilar invagination and normal groups (P<0.01 ) . It ranged from 162.7611 to 163.9701 for normal individuals and 143.0796to 146.7204 for the patients with basilar invagination. There was no overlap between them . 4. The ratio of the depth of the anterior and posterioy rims of foramen magnum have no obvious statistical sex and age difference in normal groups (P>0.05) . There were very obvious statistical difference between the patients with basilar invagination and normal groups (P<0.01 ) . It ranged from 1.0451 to 1.0784 for normal individuals and 0.7183 to 0.7957 for the patients with basilar invagination. There was no overlap between them . Conclusion: 1 . Because of the structure and the head gravity, most of the basilar invagination take place in the anterior rims of foramen magnum.which demonstrates that the depth of the anterior rim of foramen magnum reduces. Most of the depth of the posterior rim of foramen magnum has no obvious statistical difference between the normal individuals and the patients with basilar invagination. the angle between medulla oblongata and upper spinal cord becomes smaller due to the oppression of the the anterior rim of the foramen magnum which caves in. 2. The depth of the anterior and posterior rims of foramen magnum and the angle between medulla oblongata and upper spinal cord have regular rules of change in all life and have definite normal value ranges. With their...