gms | German Medical Science

Objective: Diffusion-tensor weighted imaging (DTI) in flexion-extension may serve as a tool to further improve the sensitivity for the detection of myelopathy. In this study, the feasibility and reproducibility of dynamic flexion-extension DTI in the cervical spinal cord was assessed in healthy volunteers and patients.

Methods: Healthy volunteers without complaints and patients with a clinical suspicion of spinal cord compression were enrolled in this prospective study. A cervical spine study with T2-weighted and DTI sequences was performed using a 3T MRI-scanner. The examination was repeated in maximum neck flexion and extension. Range of motion, duration of scan and space available for the cord were assessed. Fractional anisotropy (FA) and apparent diffusion coefficients (ADC) were calculated and compared between the extended, neutral and flexed neck positions. Measurements were obtained at an index level (C2/3) and compared to C4/5 in healthy subjects and the diseased segment in patients (between C3/4 and C6/7).

Results: The healthy volunteer group consisted of sixteen and the patient group of eleven subjects. Baseline parameters were well matched except for lower age in the healthy volunteer compared to the patient group (p=0.01). Flexion-extension MRI of the cervical spine was well tolerated by all subjects. Neck extension in the scanner was limited to an average of 29° in patients compared to 40° in volunteers (p=0.02). Extension led to a marked narrowing of the spinal canal on T2-weighted imaging (p<0.01 for segments C3/4 to C6/7) in both groups. Volunteers showed no variation in ADC and FA values throughout the kinematic study. In patients, ADC values in flexion, neutral position and extension were 1226±206 x10-3mm2/s, 1240±199 x10-3mm2/s and 1439±213 x10-3mm2/s, respectively, revealing a statistically significant difference between the values measured at C2/3 and at the pathology (p<0.001). Moreover, ADC-values at the diseased segments were higher in the extension position than those measured in neutral position and extension (p<0.01).

Conclusion: Dynamic flexion-extension MRI of the cervical spine safe and feasible in healthy subjects and patients. In our patient population, this resulted in a marked increase of ADC values in extension. This finding may open a previously unexplored avenue to attempt an earlier identification of myelopathy.