RESUMO
Objective To evaluate the diagnostic advantage of the ratio of ligamentum flavum(LF) thickness to oblique canal diameter(TODR)measured on CT images in patients with lumbar canal stenosis. Methods Seventy-one patients underwent CT and MRI examinations respectively,and they were divided into two groups,the positive group and negative group,according to the presence or absence of dural sac notch caused by the LF on bilateral parasagittal MR images.Meanwhile,50 volunteers without any symptom in the lumbar region or legs were examined by CT.TODRs were measured at the L3—S1 levels of the inferior margin of the intervertebral disc on transverse CT images,respectively.The results were further analyzed with the positive findings on MR images,clinical symptoms and physical examination,so as to find out the statistical correlation between them.Results LF thickness was(3.01?0.72)mm and TODR was 0.19?0.04 in the negative group,(3.94?0.84)mm and 0.28+0.06 in the positive group,and(3.16? 0.85)mm and 0.19?0.04 in the control group.There was significant difference between positive group and negative group or control group for LF thickness(P0.24, the sensitivity,specificity and positive predictive value were 74.8%,89.6% and 73.6% respectively. Positive correlation existed between LF thickness or TODR and clinical symptom(r=0.72,0.86,P