A potential method for identifying dural ossification by measuring the degree of spinal stenosis in thoracic ossification of ligamentum flavum.

Ossification of ligamentum flavum (OLF) is increasingly recognized as the major cause of thoracic spinal stenosis. The dura mater beneath ossified ligamentum flavum may also ossify when the spinal stenosis develops to a certain degree. Preoperative diagnosis of dural ossification (DO) is beneficial for surgical management of OLF. However, currently, accurate diagnosis method still could not be obtained. Based on the association between spinal stenosis and OLF/DO, a potential diagnosis method is proposed in this paper: identifying DO by measuring the degree of spinal stenosis in thoracic OLF. In the early stage of OLF, there is only mild spinal stenosis and no DO. With the progression of OLF, dura may also ossify and further compress the spinal cord, aggravating spinal stenosis. Before DO, the dura mater is presented as a low signal intensity. Once ossifying, the dura mater will be shown as a high signal intensity in CT. It will lead that the degree of spinal stenosis measured in axial CT scan obviously increases. Thus, it provides a possibility to find a critical value of it for distinguishing OLF patients with or without DO.