Line scan diffusion tensor MRI at low magnetic field strength: feasibility study of cervical spondylotic myelopathy in an early clinical stage.

PURPOSE

To implement line scan diffusion tensor MR imaging (LSDTI) on a 0.2 Tesla MR imager, and investigate the findings in the spinal cord of patients with cervical spondylotic myelopathy in an early clinical stage.

MATERIALS AND METHODS

Fourteen patients with clinical symptoms of cervical myelopathy underwent LSDTI. The signal-to-noise ratio (SNR) in the spinal cord and cerebrospinal fluid (CSF) was evaluated. The apparent diffusion coefficient (ADC) and fractional anisotropy (FA) were measured. We classified the ROIs into two groups: 1) unaffected (no clinical symptoms and no abnormality on conventional images) and 2) affected (some clinical symptoms but no abnormal signal on conventional images). Three-dimensional (3D) fiber-tracking was also studied.

RESULTS

The isotropic ADC values (10(-3)mm2/sec) were 1.28 +/- 0.11 in group 1 and 1.59 +/- 0.23 in group 2. The FAs were 0.55 +/- 0.07 in group 1, and 0.47 +/- 0.11 in group 2. The ADC value in group 2 increased (P < .001, Mann-Whitney U-test) and the FA in group 2 decreased (P = 0.24) on average, compared to those in group 1. 3D fiber-tracking was successful in 64% (9/14) of the cases.

CONCLUSION

LSDT images at low field strength may be a sensitive method for elucidating the structural characteristics of spinal cord pathology in vivo. However, clinical correlation and a long-term follow-up study will be needed.