Article Figures & Data
Figures
- Fig 1.
ROI definition. A whole section of magnitude (A) and QSM images (B) show 1 cortical lesion (red arrows) and 1 WM lesion (blue arrows). C, The ROIs of the cortical lesion and its adjacent normal-appearing cortical gray matter counterpart are delineated in red and green lines, respectively. D, The ROIs of the WM lesion and its adjacent normal-appearing white matter counterpart are delineated in blue and pink lines, respectively. ROIs were first defined on T2*-spoiled gradient-recalled images and then transferred to the other coregistered images. The gap between the lesion ROIs and the adjacent normal-appearing parenchyma reduces the partial volume effect in the segmentation. CSFnMPRAGE indicates CSF-nulled MPRAGE; WMnMPRAGE, WM-nulled MPRAGE.
- Fig 2.
Relative susceptibility in MS lesions. A, The relative susceptibility in each individual lesion. Each black line on the right connects a pair of WM and cortical portions in a mixed lesion. B, The mean relative susceptibility after averaging the relative susceptibility across all lesions per type for each patient (13 patients had WM lesions, and 8 patients had cortical lesions).
- Fig 3.
MR images of representative WM and cortical lesions from patients 4 (A) and 5 (B). A whole section of the T2-MPFLAIR image is displayed on the left column with a zoomed-in region (blue/red square) for all image contrasts. Two WM lesions (blue arrows) and 3 cortical lesions (red arrows) are shown. WM and cortical lesions are hyper- and hypointense relative to their adjacent parenchyma on QSM images, respectively, while both types of lesions show an identical contrast on all other images. CSFnMPRAGE indicates CSF-nulled MPRAGE; WMnMPRAGE, WM-nulled MPRAGE.
- Fig 4.
MR images of the only cortical lesion from patient 2. The lesion had a positive relative susceptibility and demonstrated a hyperintense core surrounded by an asymmetric hyperintense rim, suggesting that the lesion may have iron at its edge. Please see the Fig 3 legend for image descriptions.
- Fig 5.
MR images of representative mixed lesions (yellow circles) from patients 1 (A) and 6 (B). The green dashed line divides a mixed lesion into its cortical (red arrow) and WM (blue arrow) components. A, The lesion has a QSM hypointense cortical portion and a hyperintense WM portion relative to adjacent normal-appearing GM and normal-appearing WM, respectively. B, The cortical component is hypointense compared with normal-appearing GM, while the white matter component is centrally isointense but peripherally slightly hyperintense compared with normal-appearing WM. Please see the Fig 3 legend for image descriptions.
Tables
Sex Age (yr) Disease Duration (yr) Treatment Type Minimum WM Lesion Age (mo) Cortical Lesion WM Lesion Mixed Lesion Patient 1 F 37 11 Copaxoneb 12 2 6 1 2 M 42 12 Copaxone 10 1 11 0 3 F 42 3 Copaxone 8 0 2 0 4 F 30 3 Tysabric 9 5 23 1 5 F 49 2 Rebifd 18 7 13 1 6 M 32 6 Copaxone 10 3 30 4 7 M 42 1 Copaxone 7 1 5 0 8 F 33 1 Copaxone 10 0 4 0 9 F 44 15 No Treatment 6 0 4 1 10 F 31 1 No Treatment 3 0 12 0 11 F 41 16 Tysabri 4 2 15 1 12 F 58 25 Copaxone 6 6 7 0 13 M 37 8 Copaxone 13 0 15 0 14 M 48 6 Copaxone 5 0 0 0 Mean 40.4 ± 7.9 7.9 ± 7.2 8.6 ± 4.0 1.9 ± 2.3 10.5 ± 8.4 0.64 ± 1.1 Total 27 147 9 ↵a Patients 9 and 10 were not on any disease-modifying treatment at the time of their 7T scans. Patient 9 was on Tysabri, but it was stopped 6 months prior to her 7T scan. All patients had relapsing-remitting MS except patient 11, who was in a transitional stage between relapsing-remitting MS and secondary-progressive MS but was still being treated for relapsing-remitting MS. Patient 14 had lesions that all regressed before the 7T scan.
↵b Glatiramer acetate injection.
↵c Natalizumab.
↵d Interferon β-1a.
Parameters T2* SPGR T1 WM-Nulled MPRAGE T1 CSF-Nulled MPRAGE T2 MPFLAIR Acquisition 2D axial 3D coronal 3D coronal 3D coronal TR 1200 ms 8.3 ms 3.9 ms 8000 ms TE 17.7 ms 3.7 ms 8.5 ms 109.8 ms TI NA 680 ms 1200 ms 2135 ms Flip angle 60° 4° 6° 90° Bandwidth 19.2 kHz 15.6 kHz 19.2 kHz 62.5 kHz FOV 180 180 180 180 Matrix 384 × 384 180 × 180 224 × 224 224 × 224 No. of sections 90 256 256 256 Resolution 0.47 × 0.47 × 1 mm3 1 × 1 × 1 mm3 0.8 × 0.8 × 0.8 mm3 0.8 × 0.8 × 0.8 mm3 Acceleration factor ASSET 2 ARC 1.5 × 1.5 ASSET 2.5 ARC 2 × 2 Acquisition time (min:s) 6:39 5:54 6:20 5:48 Note:—ASSET indicates array spatial sensitivity encoding technique; SPGR, spoiled gradient-recalled; ARC, Autocalibrating Reconstruction for Cartesian; NA, not applicable.
↵a Two patients had a slightly different resolution for T2* SPGR. One (patient 4 in Table 1) had a resolution of 0.47 × 0.47 × 1.2 mm3 and the other (patient 11 in Table 1) had a resolution of 0.47 × 0.47 × 1.1 mm3.
WM Lesions Cortical Lesions Mixed Lesions WM Portion Cortical Portion Relative susceptibility (ppm) (per lesion type) 0.014 ± 0.014 −0.018 ± 0.013 0.014 ± 0.018 −0.009 ± 0.012 t test P < 10−22 P < 10−7 P < .043 P < .054 Relative susceptibility (ppm) (per lesion type per subject) 0.014 ± 0.010 −0.015 ± 0.009 – – t test P < .0004 P < .004 – – ↵a The null hypothesis of the t test is that the mean of relative susceptibility = 0. The significance level is .0083 after correcting multiple comparisons of 6 using the Bonferroni method.
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