The Diagnostic Value Of MR Diffusion Tensor Imaging(DTI) For Protrusion Of Lumbar Intervertebral Disc

Objective:MR DTI scans, as well as quantitative analysis are performed on intervertebral disc L4-L5 of 60 patients, thus to compare the differences and quantitative characteristics between fibrous rings of normal lumbar intervertebral discs and that of protruded ones, so as to explore the application value for DTI in the clinical diagnosis of protrusion of lumbar intervertebral disc. Method:① 1.5T Signa GE is employed to perform T1 WI, T2 WI and DTI serial MRI scan over intervertebral disc L4-L5 of 60 patients, during which the patients take supine position with heads coming into the body coil first.②The results of DTI examination performed on intervertebral disc L4-L5 of 30 patients in the hospital, who have been previously confirmed as having protrusion of lumbar intervertebral disc by MRI scan(from April 2014 to October 2014), as well as the result of the same performed on 30 healthy people in control group(who are confirmed as negative by MRI scan) are collected.③ Input the data into GE ADW 4.4 workstation, then use Functool post-processing function to generate fractional anisotropy(FA) chart and fiber tracer(FT) chart.④ Observe the continuity and completeness of fibrous rings and measure FA values for the trailing edge of a normal fibrous ring, broken fibrous ring and nucleus pulposus. Result:①1.5T Signa GE FT chart can clearly display fiber layout and shape and arrangement of inner layers inside the fibrous ring. A normal fiber ring appears in continuous and even ring shape with orderly overlapped fiber layers, while broken fibrous ring and disordered layer structure can be seen on the “protruded lumbar intervertebral disc” of a patient suffering protrusion of lumbar intervertebral disc.②FA value of fibrous ring is noticeably higher than that of nucleus pulposus, indicating they have different diffusion properties.③A normal fibrous ring appears in continuous and identical ring shape on FA chart with consecutive identical FA values.④FA value decreases for the place where fibrous ring breaks, while increases around such place. Conclusion:As an effective complement to the regular MR examination performed on intervertebral disc, the use of DTI-FT technology can display the shape and completeness of the fibrous ring around the lumbar intervertebral disc in a noninvasive way, thus to identify as whether the fibrous ring is broken or the breaking point of it. FA value can reflect the change of diffusing capacity for water molecules of intervertebral disc, and in this way, it reflects quantitatively the change of fibrous ring on protrusion of lumbar intervertebral disc and the physiological process for nucleus pulposus at its early stage of degeneration. DTI technology can provide imaging basis for the diagnosis of the protrusion of lumbar intervertebral disc, and is also conducive to the understanding of its generation mechanism.