Imaging Analysis Of Ossification Of Ligamentum Flavum Associated With Dural Adhesions

Objective To summarize the characteristic imaging signs of ossification of the ligamentum flavum (OLF) associated with dural adhesions by analyzing retrospectively the imaging signs of ossification of OLF associated with dural adhesions.Methods A retrospective analysis was made on clinical data of85patients undergoing OLF surgery between Feb.2011and Sep.2012. The patients were assigned into the study group and the control group according to the preoperative imaging signs.Of85patients35had both "tram track sign" and "jagged line sign" as the study group and51had either "tram track sign" or "jagged line sign" and neither of them in the control group. Adherence between dura mater and ligamentum flavum was observed during operation as the gold standard for the diagnosis of dural adhesion. The imaging information of CT and MRI in sagittal and axial planes was analyzed. The typical characteristics of dural adhesions were found. Then the sensitivity, and specificity and positive likelihood ratio of the preoperative imaging examinations were calculated to estimate the reference value and diagnostic value of the imaging examination was estimated (>5having reference value, and>10having diagnostic value).Results In the studied group, dural adhesion was observed in26patients (10males and16females), and the other8patients had no dural adhesion. In the controlled group, dural adhesion was found in2female patients who had "jagged line sign", and49patients had no dural adhesion (14males and35females). In patients having both "tram track sign" and "jagged line", the sensitivity was92.9%; the specificity of was86.0%; and the positive likelihood ratio was6.6. In patients having "tram track sign", the sensitivity was92.9%; the specificity was64.9%; and the positive likelihood ratio was2.6. In patients having "jagged line sign", the sensitivity was100%; the specificity was77.2%; and the positive likelihood ratio was4.4.Conclusion For patients with OLF having both "tram track sign" and "jagged line sign", preoperative CT and MRI have a reference value for diagnoses of the ossification of the ligamentum flavum associated with dural adhesions.