Axial 3D gradient-echo imaging for improved multiple sclerosis lesion detection in the cervical spinal cord at 3T

Abstract

Introduction: In multiple sclerosis (MS), spinal cord imaging can help in diagnosis and follow-up evaluation. However, spinal cord magnetic resonance imaging (MRI) is technically challenging, and image quality, particularly in the axial plane, is typically poor compared to brain MRI. Because gradient-recalled echo (GRE) images might offer improved contrast resolution within the spinal cord at high magnetic field strength, both without and with a magnetization transfer prepulse, we compared them to T2-weighted fast-spin-echo (T2-FSE) images for the detection of MS lesions in the cervical cord at 3T.

Methods: On a clinical 3T MRI scanner, we studied 62 MS cases and 19 healthy volunteers. Axial 3D GRE sequences were performed without and with off-resonance radiofrequency irradiation. To mimic clinical practice, all images were evaluated in conjunction with linked images from a sagittal short tau inversion recovery scan, which is considered the gold standard for lesion detection in MS. Two experienced observers recorded image quality, location and size of focal lesions, atrophy, swelling, and diffuse signal abnormality independently at first and then in consensus.

Results: The number and volume of lesions detected with high confidence was more than three times as high on both GRE sequences compared to T2-FSE (p < 0.0001). Approximately 5 % of GRE scans were affected by artifacts that interfered with image interpretation, not significantly different from T2W-FSE.

Conclusions: Axial 3D GRE sequences are useful for MS lesion detection when compared to 2D T2-FSE sequences in the cervical spinal cord at 3T and should be considered when examining intramedullary spinal cord lesions.

Fig. 1

Axial T2-weighted fast-spin-echo (a), gradient-echo (b), and magnetization transfer-prepared gradient-echo (c) images at the C4 vertebral body level in a 23-year-old healthy woman. Note the excellent contrast between the gray and white matter on the gradient-echo images, particularly on the magnetization transfer-prepared image. Typical flow artifacts within the CSF are apparent on the T2-weighted image

Fig. 2

Sagittal short tau inversion recovery (a), axial T2-weighted fast-spin-echo (b), axial gradient-echo (c), and axial magnetization transfer-prepared gradient-echo (d) images of the spinal cord of a 25-year-old man with relapsing–remitting multiple sclerosis. Note bilateral cord lesions within the lateral columns at the C4 vertebral body level. No focal swelling or atrophy is present

Fig. 3

Sagittal short tau inversion recovery (a), axial T2-weighted fast-spin-echo (b), axial gradient-echo (c), and axial magnetization transfer-prepared gradient-echo (d) images of the spinal cord of a 55-year-old woman with secondary-progressive multiple sclerosis. There are bilateral lesions within the lateral columns, as well as a dorsal column lesion, at the C4-5 intervertebral disk level. Both raters judged this spinal cord to be diffusely atrophic

Fig. 4

Estimated cervical spinal cord lesion count (a) and lesion burden (b; see “Materials and methods” for details), as detected on T2-weighted fast-spin-echo (T2-FSE, left), gradient-echo (GRE, center), and magnetization transfer-prepared gradient-echo (MT-GRE, right) sequences. HV, healthy volunteers; RRMS, relapsing–remitting MS; SPMS, secondary-progressive MS; PPMS, primary-progressive MS. For lesion count, orange lines represent the median for each group; for lesion burden, orange lines and error bars represent the mean and its standard error