Abstract
Background: Hypointense lesions on T1-weighted images have important clinical relevance in multiple sclerosis patients. Traditionally, spin-echo (SE) sequences are used to assess these lesions (termed black holes), but Fast Spoiled Gradient-Echo (FSPGR) sequences provide an excellent alternative.Objective: To determine whether the contrast difference between T1 hypointense lesions and the surrounding normal white matter is similar on the two sequences, whether different lesion types could be identified, and whether the clinical relevance of these lesions types are different.Methods: Seventy-nine multiple sclerosis patients' lesions were manually segmented, then registered to T1 sequences. Median intensity values of lesions were identified on all sequences, then K-means clustering was applied to assess whether distinct clusters of lesions can be defined based on intensity values on SE, FSPGR, and FLAIR sequences. The standardized intensity of the lesions in each cluster was compared to the intensity of the normal appearing white matter in order to see if lesions stand out from the white matter on a given sequence.Results: 100% of lesions on FSPGR images and 69% on SE sequence in cluster #1 exceeded a standardized lesion distance of Z = 2.3 (p < 0.05). In cluster #2, 78.7% of lesions on FSPGR and only 17.7% of lesions on SE sequence were above this cutoff value, meaning that these lesions were not easily seen on SE images. Lesion count in the second cluster (lesions less identifiable on SE) significantly correlated with the Expanded Disability Status Scale (EDSS) (R: 0.30, p ≤ 0.006) and with disease duration (R: 0.33, p ≤ 0.002).Conclusion: We showed that black holes can be separated into two distinct clusters based on their intensity values on various sequences, only one of which is related to clinical parameters. This emphasizes the joint role of FSPGR and SE sequences in the monitoring of MS patients and provides insight into the role of black holes in MS.
Highlights
Multiple sclerosis (MS) is a chronic, progressive disease affecting the central nervous system in young adults leading to demyelination and axonal loss [1]
The first description of the association between black holes (BHs) and the clinical state of MS patients was published by Truyen et al Using spin-echo (SE) MRI sequences in their 40-month followup study they showed that patients’ baseline disabilities correlated significantly with BH lesion load, and in the case of secondary progressive MS, the accumulation of BHs contributed to the progression rate as well
Our results showed that lesions on average were separable from the surrounding white matter on both Fast Spoiled Gradient-Echo (FSPGR) and SE images
Summary
Multiple sclerosis (MS) is a chronic, progressive disease affecting the central nervous system in young adults leading to demyelination and axonal loss [1]. The first description of the association between BHs and the clinical state of MS patients was published by Truyen et al Using spin-echo (SE) MRI sequences in their 40-month followup study they showed that patients’ baseline disabilities correlated significantly with BH lesion load, and in the case of secondary progressive MS, the accumulation of BHs contributed to the progression rate as well. They suggested that the presence of BHs led to a failed remission [5]. Spin-echo (SE) sequences are used to assess these lesions (termed black holes), but Fast Spoiled Gradient-Echo (FSPGR) sequences provide an excellent alternative
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