Contribution of the MP2RAGE 7T Sequence in MS Lesions of the Cervical Spinal Cord

Abstract

Background and purpose: The detection of spinal cord lesions in patients with MS is challenging. Recently, the 3D MP2RAGE sequence demonstrated its usefulness at 3T. Benefiting from the high spatial resolution provided by ultra-high-field MR imaging systems, we aimed to evaluate the contribution of the 3D MP2RAGE sequence acquired at 7T for the detection of MS lesions in the cervical spine.

Materials and methods: Seventeen patients with MS participated in this study. They were examined at both 3T and 7T. The MR imaging examination included a Magnetic Imaging in MS (MAGNIMS) protocol with an axial T2*-WI gradient recalled-echo sequence ("optimized MAGNIMS protocol") and a 0.9-mm isotropic 3D MP2RAGE sequence at 3T, as well as a 0.7-mm isotropic and 0.3-mm in-plane-resolution anisotropic 3D MP2RAGE sequences at 7T. Each data set was read by a consensus of radiologists, neurologists, and neuroscientists. The number of lesions and their topography, as well as the visibility of the lesions from one set to another, were carefully analyzed.

Results: A total of 55 lesions were detected. The absolute number of visible lesions differed among the 4 sequences (linear mixed effect ANOVA, P = .020). The highest detection was observed for the two 7T sequences with 51 lesions each (92.7% of the total). The optimized 3T MAGNIMS protocol and the 3T MP2RAGE isotropic sequence detected 41 (74.5%) and 35 lesions (63.6%), respectively.

Conclusions: The 7T MP2RAGE sequences detected more lesions than the 3T sets. Isotropic and anisotropic acquisitions performed comparably. Ultra-high-resolution sequences obtained at 7T improve the identification and delineation of lesions of the cervical spinal cord in MS.

FIG 1.

Proportion of lesion detection by sequence (A) and by sequence per vertebral level (B) for the patients having the 4 imaging sets (14 patients). The number of lesions (n) is detected for each cervical level.

FIG 2.

Axial presentation at the C4 level for patient P11. Images were acquired with the T2*-WI GRE (A), 3T UNI MP2RAGE (B), 7T isotropic UNI MP2RAGE (C), and 7T anisotropic UNI MP2RAGE (D) sequences. The posterior lesion was visible on each image, the right lateral lesion was not visible on the 3T UNI MP2RAGE sequence (B), and the left lateral lesion (white arrowhead) was only detected with the 7T anisotropic UNI MP2RAGE sequence (D).

FIG 3.

A patient P13 presenting with a C4 left lateral lesion (arrowhead). The lesion was not detected on axial T2*-WI GRE image (A), the 3T UNI MP2RAGE (B), nor the 7T isotropic UNI MP2RAGE (C). It was only detected using the 7T anisotropic UNI MP2RAGE (D).

FIG 4.

Patient P17 presented with a small lesion (arrowhead) in contact with the anterior fissure of the spinal cord at the C1–C2 level. The lesion was seen on a T2*-WI GRE (A) image, not seen on 3T UNI MP2RAGE (B), and easily seen on 7T anisotropic UNI MP2RAGE (C) image.

FIG 5.

Patient P3 presented with a small posterior lesion (white arrowhead) at the C1 level that was not seen on axial T2*-WI GRE (A) image nor with 3T UNI MP2RAGE (B). At 7T, the lesion was seen on the axial plane of the isotropic UNI MP2RAGE sequence (C), but it was not seen on the anisotropic 7T UNI MP2RAGE image (D). The sagittal plane (E) of the 7T isotropic UNI MP2RAGE sequence shows that this lesion (white arrowhead) has a small height. This lesion is not seen on the sagittal 3T UNI MP2RAGE (F). Additional lesions (white arrows) can be seen at the C3 and C5 levels on both sagittal planes (E and F).