Magnetic resonance diffusion tensor imaging for occult lesion detection in multiple sclerosis

Abstract

It remains challenging to locate occult lesions in patients with multiple sclerosis (MS). Diffusion tensor imaging (DTI) has been demonstrated to have the potential to identify occult changes in MS lesions. The present study used 3.0T magnetic resonance DTI to investigate the characteristics of different stages of MS lesions. DTI parameters, fractional anisotropy (FA), mean diffusivity (MD), λ// and λ┴ values of lesions were compared at the different stages of 10 patients with MS with 10 normal controls. The results demonstrated that FA and λ// values of MS silent and subacute lesions are decreased and MD and λ┴ values are increased, as compared with those of normal appearing white matter (NAWM) and normal controls. NAWM FA values were lower, and MD, λ//, and λ┴ values were higher than those of normal controls. It was also indicated that MS lesions had reduced color signals compared with the controls, and the lesion area appeared larger using DTI as compared with diffusion-weighted imaging. Furthermore, fiber abnormalities were detected in MS lesions using DTT, with fewer fibers connected to the lesion side, as compared with the contralateral side. FA, MD, λ// and λ┴ values in the thalamus were increased, as compared with those of normal controls (P<0.05); whereas MD, λ// and λ┴ values were significantly increased and FA values significantly decreased in the caudate nucleus and deep brain gray matter (DBGM) of patients with MS, as compared with the controls (P<0.05). λ// and λ┴ values were also significantly increased in the DBGM of patients with MS as compared with normal controls (P<0.05). The present findings demonstrate that DTI may be useful in the characterization of MS lesions.

Keywords: deep gray matter; diffusion tensor imaging; diffusion tensor tractography; multiple sclerosis; thalamus.

Figure 1.

Images from a 27 year old patient admitted with slurred speech that lasted for one week. (A) Diffusion-weighted imaging showing right corona radiate abnormal signal. (B) FA illustrating the reduced signal at the right side of the lesion as compared with the surrounding normal tissue. (C) Directionally-encoded color map indicating that the signal at the right lesion was significantly reduced. (D) As shown using FA, bilateral corona radiata tracking ROIs fiber bundles in the corticospinal tract fibers corresponding to the fiber interruption and multiple sclerosis lesions. (E) Indicating the ROIs fibers of the lesions, the interruption of reconstructed fibers is evident at site of the lesion, with fewer fibers at the lesion site as compared with the contralateral side. FA, fractional anisotropy.