ABSTRACT
Objective To study the feasibility and clinical values of diffusion tensor tractography (DTT)in the spinal cord at 3.0 T MR.Methods Forty patients with spinal cord compression including cervical cord herniation and cervical spondylosis(30 cases),tumors in spinal canal(9 cases)and old injury in cervical vertebrae(1 cases)and 20 healthy volunteers participated in this study.Single-shot spin- echo echo-planar diffusion tensor sequence for tractography of the spinal cord was performed.The fibers of spinal cord were visualized by using fiber tracking software.Results On the DTT maps,the normal spinal cord was depicted as a fiber tract showing color-encoded cephaloeaudally,which indicated anisotropy in the cephalocaudal direction.By setting two ROI,the main spinal cord fiber tracts,such as corticospinal or spinothalamic tract,were visualized.The tracts from two sides of the brain did not completely cross.It was asymmetric in the number of tracts on the two sides in most normal subjects(8/10).The tracts of all patients with cord compression were seen oppressed or damaged in different degrees.The DrrT in patients with cervical spondylosis and extramedullary-intradural neurolemmoma demonstrated that tracts were oppressed but not damaged.The DTT in one ependymoma showed that tract was markedly compressed and slightly damaged.Conclusion DTT is a promising tool for demonstrating the spinal cord tracts and abnormalities,can provide useful information for the localization of compression and evaluation of the impairment extent on the white matter tracts of the spinal cord.
ABSTRACT
Objective To investigate the techniques and influence factors for the respiratory navigator echo triggered whole-heart coronary MR angiography(WH-CMRA)and evaluate its application in visualizing coronary arteries and the image quality.Methods Ninety two volunteers were acquired with WH-CMRA at 3 T MR scanner using respiratory navigator-echo gated TFE sequence.Imaging quality was visually graded as 0—Ⅳ grade according to the visual inspection,average length,diameter and sharpness of coronary arteries.The correlation between the imaging quality and respiratory pattern,heart rate and navigator efficiency was analyzed.Results The imaging quality in 92 cases was that 28 were graded as Ⅳ, 53 were graded as Ⅲ,9 were graded as Ⅱ and 2 were graded as Ⅰ.The successful rate of scan was 88% (81/92).The imaging quality is mainly graded as Ⅳ when the heart rate was less than 75 beats per minute (bpm)and the sharpness of vessel was(48?11)%.When heart rate was more than 75 bpm,the image quality was mostly graded as Ⅲ and the sharpness was(33?15)%.The correlation between heart rate and imaging quality score was negative(r=-0.726,P0.05).Conclusion 3 T WH-CMRA technique could facilitated the visualization of whole coronary arteries at free breathing but having indications on heart rate.