Functional Analysis of the Vertebral Column Based on MR and Direct Volume Rendering

Degenerative diseases of the vertebral column are mainly combined with misalignments of the intervertebral discs and deformations of the spinal cord. For the investigation of severe spinal stenosis and herniated intervertebral discs x–ray myelography is required providing important functional information about the motion of vertebral segments. Avoid this time–consuming procedure and the injection of contrast agent, we introduce a non–invasive approach using direct volume rendering of MR–MEDIC volumes. It provides meaningful representations of extreme spinal pathologies. Above all, the essential functional information about different motion states is obtained using a newly developed device which is applied directly in the MR scanner. Due to the distribution of the grey values, we suggest a coarse segmentation of the vertebral column. This is achieved with a fast sequence of filtering operations and volume growing. Further on, details are delineated implicitly using interactive adjustment of transfer functions. Thereby, the CSF, the roots of the spinal nerves and the vertebrae are clearly visible. Additionally, we propose a convenient approach for volumetric measurement providing the functional dependence of the CSF volume. In consequence, the presented non–invasive approach gives a comprehensive understanding of spatial and functional information including spinal instability and may thus considerably lead to further reduce the need of x–ray myelography.