Evaluation of Focal Cervical Spinal Cord Lesions in Multiple Sclerosis: Comparison of White Matter-Suppressed T1 Inversion Recovery Sequence versus Conventional STIR and Proton Density-Weighted Turbo Spin-Echo Sequences

Abstract

Background and purpose: Conventional MR imaging of the cervical spinal cord in MS is challenged by numerous artifacts and interreader variability in lesion counts. This study compares the relatively novel WM-suppressed T1 inversion recovery sequence with STIR and proton density-weighted TSE sequences in the evaluation of cervical cord lesions in patients with MS.

Materials and methods: Retrospective blinded analysis of cervical cord MR imaging examinations of 50 patients with MS was performed by 2 neuroradiologists. In each patient, the number of focal lesions and overall lesion conspicuity were measured in the STIR/proton density-weighted TSE and WM-suppressed T1 inversion recovery sequence groups. Independent side-by-side comparison was performed to categorize the discrepant lesions as either "definite" or "spurious." Lesion contrast ratio and edge sharpness were independently calculated in each sequence.

Results: Substantial interreader agreement was noted on the WM-suppressed T1 inversion recovery sequence (κ = 0.82) compared with STIR/proton density-weighted TSE (κ = 0.52). Average lesion conspicuity was better on the WM-suppressed T1 inversion recovery sequence (conspicuity of 3.1/5.0 versus 3.7/5.0, P < .01, in the WM-suppressed T1 inversion recovery sequence versus STIR/proton density-weighted TSE, respectively). Spurious lesions were more common on STIR/proton density-weighted TSE than on the WM-suppressed T1 inversion recovery sequence (23 and 30 versus 3 and 4 by readers 1 and 2, respectively; P < .01). More "definite" lesions were missed on STIR/proton density-weighted TSE compared with the WM-suppressed T1 inversion recovery sequence (37 and 38 versus 3 and 6 by readers 1 and 2, respectively). Lesion contrast ratio and edge sharpness were highest on the WM-suppressed T1 inversion recovery sequence.

Conclusions: There is better interreader consistency in the lesion count on the WM-suppressed T1 inversion recovery sequence compared with STIR/proton density-weighted TSE sequences. The focal cord lesions are visualized with better conspicuity due to better contrast ratio and edge sharpness. There are fewer spurious lesions on the WM-suppressed T1 inversion recovery sequence compared with STIR/proton density-weighted TSE. The WM-suppressed T1 inversion recovery sequence could potentially be substituted for either STIR or proton density-weighted TSE sequences in routine clinical protocols.

Fig 1.

Measurement of lesion edge sharpness on a sagittal WMS image in a 39-year-old woman with a relapsing-remitting subtype of multiple sclerosis. A line is drawn along the long axis of the lesion located at the C2–C3 level, which includes the adjoining normal-appearing cord. The histogram derived represents the signal-intensity profile along the line. Lesion edge sharpness is determined by the average of distance required for a 20%–80% change in the signal intensity at the upper and lower margins of the lesion.

Fig 2.

Example of improved lesion conspicuity in a 45-year-old woman with a relapsing-remitting subtype of multiple sclerosis. Sagittal STIR (A) and PDWTSE (B) images show a focal lesion in the dorsum of the cord at the lower C2 level (arrow). Anterior to this lesion, there is linear hyperintensity in the center of the cord usually noted on the STIR/PDWTSE sequence group (arrowhead). The central canal is more homogeneous in signal intensity on sagittal WMS image (C); this feature improves the definition of the superior margin of the dorsal lesion. An additional focal lesion is noted in the ventral cord at the upper C2 level (open arrow), better identified on the WMS sequence (C).

Fig 3.

An example of a definite lesion missed on STIR/PDWTSE in a 40-year-old woman with multiple sclerosis. Sagittal STIR (A) and PDWTSE (B) images show focal lesions at the C3 and C6 levels (arrowheads). Another lesion at the C2 level (arrow) is less conspicuous due to central cord high signal in STIR/PDWTSE. On WMS (C), the lesion at C2 is better visualized. An additional focal lesion is noted on WMS at the C4 level (open arrow), which is identified on PDWTSE as a faint hyperintensity on the side-by-side comparison.