Correlation study between 3 T MR DTI measurements and symptoms in patients with cervical spondylotic myelopathy

Objective: To evaluate the correlation between diffusion tensor imaging (DTI) measurements,fiber tracking (FT) and the clinical symptoms in patients with cervical spondylotic myelopathy. Methods: According to the Japanese orthopaedics association score (JOA), 104 patients with cervical spondylopathy were divided into 4 groups: mild in 31 patients with 13-16 scores, moderate in 27 with 9-12 scores, severe in 25 with 5-8 scores, and serious in 21 with 0-4 scores. According to the lesion signal characters, all patients were divided into 3 groups: Group A with normal signal in both T₁WI and T₂WI in 33 patients, Group B with normal signal in T₁WI but high signal in T₂WI in 30 patients, and Group C with low signal in T₁WI and high signal in T₂WI in 41 patients. Apparent diffusion coefficient (ADC), fractional anisotropy (FA), λ₁, λ₂, λ₃ were measured in the spinal cord at the serious pressed section,and fiber tractography was performed. The Spearman correlation analyses was used to correlate each of the DTI measurement with JOA score. Group difference was tested with one-way ANOVA method. Results: High quality of DTI was acquired in all patients. The FA values in the mild, moderate,severe, and serious groups were respectively 0.69 ±0.13, 0.58 ±0.03, 0.46 ±0.08, and 0.37 ±0.11 and significant difference was found in different groups (F=100.59, P<0.05) and positively correlated with JOA scores (r=0.883, P<0.05). There was no statistical significance between JOA scores and ADC, λ₁, λ₂, λ₃ (r=0.232, 0.217, 0.113, 0.127, P>0.05). The FA values in group A, B, and C were respectively 0.67 ±0.33, 0.51 ±0.21, 0.38 ±0.03, and significant difference was found among different groups (F=50.05, P<0.05). Decrease of JOA score and high signal in T₂ accompanied with decrease of FA value. Decrease of FA values was found associated with increase of fiber bundle damage. The ADC, λ₂, λ₃ but not λ₁ were significantly different among the JOA groups and the group A, B,and C. Conclusions: The FA values are positively correlated with clinical symptoms. Decrease of FA values is found associated with increase of fiber bundle damage. DTI can show the severity and extent of damage of spinal cord in patients with cervical spondylotic myelopathy. (authors)