A dual-channel surface receive coil was fixed on the back corresponding to the thoracic spinal cord, and the head was lifted by a head sheath to reduce the amplitude of respiratory movement and to avoid obvious movements during scanning. Anesthetized animals were placed in the supine position, fixed with foam pads and adhesive tapes located in the forelimbs, hindlimbs, and abdomen.

Rats were anesthetized by intraperitoneal injection of ketamine (60 mg/kg) and xylazine (10 mg/kg). The optimal b value setting for spinal cord DTI under the 7 T scanner was explored and evaluated through these four indicators.Īll datasets were collected in vivo by using the Bruker BioClinScan Animal MRI System (bore size 31 cm, gradient field strength 290 mT/m, and slew rate 1160 T/m/s) dedicated to small animals. Image quality (including image SNR and image distortion degree) and data quality (including data stability and data consistency) were calculated under different b value settings. In this study, the DTI data of normal and spinal cord-injured animals were collected by using the ultrahigh field strength (7 T) MR instrument. Therefore, it is essential to explore the most appropriate b value in the DTI sequence under the ultrahigh field strength. However, it is still unclear whether the optimal b value obtained at the low field strength (1.5 T) can accurately guide that at the ultrahigh field strength. Although there have been some achievements in the study of optimal b value settings at low field strength, researchers often need to use the ultrahigh field strength MR equipment in the basic research of SCI to obtain precise DTI images. In the comparison of SNR, fractional anisotropy (FA), and MD under these six settings, it is suggested that the SNR, FA, and MD of imaging results are the best when the voxel size is 2.5 × 2.5 × 2.5 mm 3, and the b value is 700 or 1000 s/mm 2. Six sets of parameter settings were formed under three b values: 700, 1000, and 1200 s/mm 2. performed a human whole brain DTI at 1.5 T scanner and used two settings of voxel size: 2.0 × 2.0 × 2.0 mm 3 and 2.5 × 2.5 × 2.5 mm 3. evaluated the DTI imaging quality of lumbar nerve root at b = 200, 400, and 800 s/mm 2 by using 1.5 T MRI and reported the less distortion of DTI images at 400 s/mm 2. Therefore, to some extent, the setting of b value will determine the reliability of DTI results.Īt present, many studies focus on the exploration of the optimal b value in DTI sequence at the low field strength of MR scanner. performed brain DTI on 13 healthy subjects and found that the increase of b value would lead to the decrease of mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) when the gradient directions and voxel resolution remained constant. assessed the parameter setting of DTI in normal human brain and revealed that the increase of b value generally leads to the decrease of signal-noise ratio (SNR) of DTI image. investigated the dynamic correlation of DTI and neurological function scores in spinal cord-injured beagles and showed that DTI has the potential to accurately predict the recovery of neurological function after SCI.ĭuring scanning, the setting of sequence parameters will affect the DTI results, and the diffusion sensitivity coefficient b value is one of them. It is proved that DTI technique can noninvasively reflect the spatiotemporal characteristics of SCI-induced white matter fiber bundles degeneration and can directly show the damage of white matter fiber tracts. used spinal cord contused Wistar rats to analyze the DTI data and behavioral scores before SCI, and 1, 3, 7, 14, and 84 days post SCI.

At present, there are many researches on SCI using DTI technology. Diffusion tensor imaging (DTI), a special MRI technique, can reflect the alterations of tissue microstructure by measuring the water diffusion motion, so it has important application prospects in evaluating the severity of SCI and its therapeutic effects. Magnetic resonance imaging (MRI) is an important imaging method to detect spinal cord injury (SCI) at present, but conventional MRI has deficiencies in detecting the microstructure of spinal cord tissue and the integrity of white matter fiber tracts.

Medinria tractography