Study on lumbosacral nerve root compression using DTI

Abstract

Abstract. Diffusion tensor imaging (DTI) can objectively describe the distribution of nerve roots in morphology, and provide a set of objective reference data on the quantitative indicators. The present study aimed to investigate the value of DTI in lumbosacral nerve root compression in patients with lumbar intervertebral disc degeneration. DTI was performed in 45 patients with lumbar intervertebral disc degeneration. Apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values were measured in compressed and normal nerve roots. Fiber tracking imaging was also applied to observe the lumbosacral nerve roots. ADC value was significantly lower in the compressed group (1.314±0.14 mm 2 /sec) compared to in the uncompressed group (1.794±0.11 mm 2 /sec) (P<0.05). The FA value was significantly lower in the compressed group (0.196±0.020) compared to the uncompressed group (0.272±0.016) (P<0.05). DTI can evidently reveal the compressed nerve roots. DTI could be used to evaluate the lumbosacral nerve injury in patients with lumbar intervertebral disc degeneration to quantitatively assess nerve roots. IntroductionMagnetic resonance imaging (MRI) is a commonly used advanced inspection technique in clinical and scientific research. At present, the new technology mainly includes functional MRI, magnetic resonance spectroscopy, three-dimensional spoiled gradient recalled echo and diffusion tensor imaging (DTI). These technologies have been extensively applied in the brain, spinal cord lesions and tumors.DTI is an MR technique developed on the basis of the diffusion-weighted imaging (DWI). DTI collects attenuated signal intensity induced by a diffusion of water molecules in all directions of space through a diffusion sensitive gradient in numerous directions, quantitatively describes the three-dimensional trajectory of spatial diffusion, and can provide a diffusion direction characteristic of living tissue (1). Under physiological conditions, the diffusion rate of water molecules in each direction is different, i.e., diffusion anisotropy. DTI can measure the direction and degree of diffusion of the water molecules in a three-dimensional space, describe anisotropic characteristics of tissue and precisely investigate the distribution of fibers (2,3). Diffusion anisotropy has been found in muscle, and has also been detected in the spinal cord and white matter of living tissue in the late 1980s. White matter anisotropy is induced by paralleled distributed myelinated nerve fibers (4). The diffusion of white matter was faster in paralleled fibers compared to vertical fibers. This feature with a color mark can reflect spatial directivity of the white matter. Thus, the fastest diffusion direction is the direction of fiber distribution. It is the same in DTI of skeletal muscle and myocardium. With the advancement of studies regarding DTI, the DTI application has become an area of interest for human functional imaging. Since Clark et al (5) applied DWI in the spinal cord in 1999, the application of DTI in the spinal cord al...

Microstructural changes are coincident with the improvement of clinical symptoms in surgically treated compressed nerve roots

“…As the DTI technique has evolved, the movement of water molecules can be accurately measured using DTI parameters such as the FA and ADC values. These values have been found to be capable of analysing the nerve root condition in greater detail than conventional MRI10111214.…”

“…This phenomenon is known as diffusion anisotropy, and selectively recording this information is referred to as diffusion tensor imaging (DTI). DTI is the only method that can give an indirect view of the microstructure of nervous tissue in addition to the pathway of the fibres 10 11 12 13 . The diffusion data can help determine the quantitative diffusion values, such as the ADC and fractional anisotropy (FA) values that reflect the directionality of the molecular diffusion.…”

Recent advances in magnetic resonance neuroimaging of lumbar nerve to clinical applications: A review of clinical studies utilizing Dffusion Tensor Imaging and Diffusion-weighted magnetic resonance neurography

“…A total of 683 subjects were studied across 24 DTI articles. 177 patients with lumbar spinal canal stenosis (LSCS) in 5 articles 11,12,16,17,20) , 143 patients with lumbar disc herniation (LDH) in 7 articles 7,13,15,20,21,23,29) , 112 patients with lumbar radiculopathy in 3 articles 10,19,22) , 36 patients with foraminal stenosis (FS) in 6 articles 9,11,16,20,27,28) , 2 patients with lower back pain in one article 20) , 3 cases with diastematomyelia and one case with tethered cord in one article 30) , and one case with spina bifida in one article 26) were included. 7 post mortem subjects were investigated in one article 8) .…”

“…All 17 articles 7,[9][10][11][12][13][15][16][17]19,20,22,23,[27][28][29][30] . Except for one continued.…”

Functional Assessment of Lumbar Nerve Roots Using Coronal-plane Single-shot Turbo Spin-echo Diffusion Tensor Imaging

“…1 Several studies that used EPI-DTI recently showed that tractography can visualize the lumbar nerves, and the degree of lumbar nerve damage was quantitatively evaluated using fractional anisotropy (FA) by identifying the preferential water molecule diffusion. 2 These previous studies on EPI-DTI indicated that the FA values decreased in the presence of peripheral nerve compression with nerve damage because of neurodegeneration, such as interstitial space widening, Wallerian degeneration, and axonal demyelination, which induces increased perpendicular diffusion vector compared with the normal nerves. 3 Although EPI-DTI has great potential for the evaluation of lumbar nerve compression, several problems, such as long acquisition times in obtaining a sufficient signal-to-noise ratio (SNR) using multiple signal averages, geometric distortion, and artifact susceptibility due to its high sensitivity to magnetic susceptibility, were observed.…”