Abstract
ObjectiveCompare T1 spin-echo (T1SE) and T1 gradient-echo (T1GE) sequences in detecting hypointense brain lesions in multiple sclerosis (MS). BackgroundChronic hypointense lesions on T1SE MRI scans are a surrogate of severe demyelination and axonal loss in MS. The role of T1GE images in the detection of such lesions has not been clarified. Design/methodsIn 45 patients with MS [Expanded Disability Status Scale (EDSS) score (mean±SD) 3.5±2.0; 37 relapsing-remitting (RR); 8 secondary progressive (SP)], cerebral T1SE, T1GE, and T2-weighted fluid-attenuated inversion-recovery (FLAIR) images were acquired on a 1.5T MRI scanner. Images were re-sampled to axial 5mm slices before directly comparing lesion detectability using Jim (v.7, Xinapse Systems). Statistical methods included Wilcoxon signed rank tests to compare sequences and Spearman correlations to test associations. ResultsConsidering the entire cohort, T1GE detected a higher lesion volume (5.90±6.21 vs. 4.17±4.84ml, p<0.0001) and higher lesion number (27.82±20.66 vs. 25.20±20.43, p<0.05) than T1SE. Lesion volume differences persisted when considering RR and SP patients separately (both p<0.01). A higher lesion number by T1GE was seen only in the RR group (p<0.05). When comparing correlations between lesion volume and overall neurologic disability (EDSS score), T1SE correlated with EDSS (Spearman r=0.29, p<0.05) while T1GE (r=0.23, p=0.13) and FLAIR (r=0.24, p=0.12) did not. ConclusionOur data suggest that hypointense lesions on T1SE and T1GE are not interchangeable in patients with MS. Based on these results, we hypothesize that T1GE shows more sensitivity to lesions at the expense of less pathologic specificity for tissue destruction than T1SE.
Highlights
Multiple sclerosis (MS) is an inflammatory demyelinating disease of the CNS, characterized by lesions and atrophy of the brain and spinal cord
In the RR subgroup, T1-weighted gradient-echo (T1GE) derived lesion volumes were significantly higher than T1-weighted spin-echo (T1SE) measures (4.87 ± 5.05 vs. 3.22 ± 3.49, p < 0.0001)
The purpose of this study was to clarify the role of a T1GE sequence in MS cerebral hypointense lesion detection by direct comparison to a conventional T1SE sequence
Summary
Multiple sclerosis (MS) is an inflammatory demyelinating disease of the CNS, characterized by lesions and atrophy of the brain and spinal cord. T1-weighted spin-echo (T1SE) images may show chronic hypointense lesions, which are known to represent severe/irreversible demyelination with axonal loss [1,2,3,4,5,6]. T1-weighted gradient-echo (T1GE) sequences commonly show hypointense lesions in patients with MS [7]. Such images have an increasing role in both research and clinical settings with the growing use of 3 T scanners [1,8,9]. We compared T1SE and T1GE sequences side-by-side in patients with MS to clarify to what extent hypointense lesions are interchangeable between the two pulse sequences
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