| Part I Preliminary study of DTI and tractography in normalcervical spinal cordPURPOSE: To investigate the method of DTI and draw the normal parameters of DTI of the cervical spinal cord in healthy volunteers, and to demonstrate the normal anatomy of the white matter by using fiber tracking technique in order to provide the basis for diagnosing cervical spinal cord disorders. MATERIALS AND METHODS: Twenty-two normal volunteers received conventional MRI and DTI examinations of the cervical spinal cord on a 1.5 T HD MR scanner. Parameters (ADC, FA, and RA) and eigenvalues (λ1, λ2, λ3) at different levels of the cervical spinal cord were calculated on sagittal plane. Various parameters in different regions at the same level (C3) were measured on axial image. The tractography of cervical spinal cord was acquired using fiber tracking software.RESULTS: On sagittal plane, the average values of ADC, FA and RA of the cervical spinal cord were (0.893 ± 0.274) 10~3mm2/s, 0.725 ± 0.099, and 0.720 ± 0.118, respectively, and the average values of λ1, λ2, λ3 were (1.628 ± 0.443)×10-3mm2/s , (0.604 ± 0.354)×10-3mm2/s, and (0.567 ± 0.358)×10-3mm2/s, respectively. On axial plane at C3 level, ADC, FA and RA values in the anterior funiculus were (0.893 ± 0.232)×10-3mm2/s, 0.685 ± 0.107, and 0.674 ± 0.123, respectively, (0.712 ± 0.309)×10-3mm2/s, 0.899 ± 0.078, and 0.918 ± 0.120, respectively in the posterior funiculus;(0.712±0.296)×10-3mm2/s, 0.863 ± 0.100, and 0.895 ± 0.108, respectively in the left lateral corticospinal tract (LCT), and (0.662 ± 0.259)×10-3mm2/s, 0.853 ± 0.112, and 0.880 ± 0.128,respectively in the right LCT. Maps of fiber tracking were received withoutobvious distortion and normal anatomy of the cervical spinal cord could bedemonstrated.CONCLUSIONS: Satisfactory diffusion tensor images of cervical spinal cordwere well demonstrated in vivo in healthy volunteers by using DTI and fibertracking technique with SE-EPI sequence. In sagittal view, FA and RA values ofC3 were higher than those of other levels. In axial view, FA and RA values in theanterior funiculus were lower than those of other regions, while its ADC valueswere higher than others. The tractography of cervical spinal cord can be acquiredby using fiber tracking software, which is consistent with normal anatomy of thecervical spinal cord.Part II Preliminary study of DTI in patients with ALSPURPOSE: To determine whether normal-appearing cervical spinal cord in patients with amyotrophic lateral sclerosis (ALS) have abnormal changes based on the quantitative measurement of healthy volunteers.METHOD AND MATERIALS: Conventional MRI and DTI in axial plane were obtained in 16 patients with ALS and 16 age-matched control subjects. ROIs were placed in anterior funiculus, posterior funiculus, and bilateral lateral corticospinal tracts (LCTs), respectively, at the same slice (C3). Parameters of these regions in control subjects were used for comparison.RESULTS: In ALS patients, the average values of FA were 0.637±0.113 in anterior funiculus, 0.886 ± 0.073 in posterior funiculus, 0.762 ± 0.089 in left LCT, and 0.751 ± 0.065 in right LCT, respectively. The average values of ADC were (0.950 ± 0.354)xl0"3mm2/s, (0.613 ± 0.137)xl0"3mm2/s, (0.744 ± 0.162)*10'3 mm /s, and (0.767 ± 0.141)* 10" mm /s, respectively. The average values of RA were 0.622 ± 0.138, 0.920 ± 0.100, 0.762 ± 0.107, and 0.772 ± 0.082,respectively. Data were statistically processed. In both ALS and normal controls, FA and RA values of the anterior funiculus were significantly higher than those of posterior funiculus (P<0.05), while its ADC values were lower than those of posterior (PO.05). FA, RA and ADC values showed no significant difference between left and right LCT (P>0.05). In ALS patients, FA and RA values of bilateral LCTs decreased significantly compared with those of the control group (P<0.05), but ADC values showed no significant difference (P>0.05). Parameters of the anterior and posterior funiculus in ALS patients showed no obvious change compared with the controls (P>0.05).CONCLUSIONS: DTI with SE-EPI technique is simple and sensitive in detecting the pathological changes in ALS patients. DTI can reveal the abnormalities which are "normal appearing" on conventional T2WI. |
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