Quantitative susceptibility mapping versus phase imaging to identify multiple sclerosis iron rim lesions with demyelination

Abstract

Background and Purpose: To compare quantitative susceptibility mapping (QSM) and high-pass-filtered (HPF) phase imaging for (1) identifying chronic active rim lesions with more myelin damage and ( 2) distinguishing patients with increased clinical disability in multiple sclerosis. Methods: Eighty patients were scanned with QSM for paramagnetic rim detection and Fast Acquisition with Spiral Trajectory and T2prep for myelin water fraction (MWF). Chronic lesions were classified based on the presence/absence of rim on HPF and QSM images. A lesion-level linear mixed-effects model with MWF as the outcome was used to compare myelin damage among the lesion groups. A multiple patient-level linear regression model was fit to establish the association between Expanded Disease Status Scale (EDSS) and the log of the number of rim lesions.Results: Of 2062 lesions, 188 (9.1%) were HPF rim+/QSM rim+, 203 (9.8%) were HPF rim+/QSM rim-, and the remainder had no rim. In the linear mixed-effects model, HPF rim+/QSM rim+ lesions had significantly lower MWF than both HPF rim+/QSM rim-(p < .001) and HPF rim-/QSM rim-(p < .001) lesions, while the MWF difference between HPF rim+/QSM rim-and HPF rim-/QSM rim-lesions was not statistically significant (p = .130). Holding all other factors constant, the log number of QSM rim+ lesion was associated with EDSS increase (p = .044). The association between the log number of HPF rim+ lesions and EDSS was not statistically significant (p = .206).Conclusions: QSM identifies paramagnetic rim lesions that on average have more myelin damage and stronger association with clinical disability than those detected by phase imaging.

Multiple sclerosis iron rim lesions are linked to impaired cervical spinal cord integrity using the T1/T2‐weighted ratio

“…Previous studies demonstrated that IRLs are associated with higher disease severity and ongoing tissue destruction 2–7 . Consistent with these findings, in our study, MS patients with at least one brain IRL on MRI also had higher disability scores (EDSS, pyramidal functional system), emphasizing IRLs as a novel imaging marker of disease severity.…”

“…In multiple sclerosis (MS), in vivo demonstration of chronic active lesions as paramagnetic or iron rim lesions (IRLs) on iron‐sensitive (ultra)high field MRI sequences has been suggested as a novel imaging marker of a chronic “smoldering” inflammation including ongoing myelin degradation and axonal degeneration, 1,2 associated with higher neurological disability and disease severity 2–7 …”

Lesion-level correspondence and longitudinal properties of paramagnetic rim and slowly expanding lesions in multiple sclerosis

“…Quantitative susceptibility mapping (QSM) may provide a more specific identification of paramagnetic rims that limits the effects of possible blooming artifacts. 37,38 QSM may also provide more granular quantification of iron content in the lesion rim both cross-sectionally and over time. 39 Smaller PRLs (<60 mm 3 ) had very low lesion-level correspondence (10%) with SELs.…”

Implications of quantitative susceptibility mapping at 7 Tesla MRI for microbleeds detection in cerebral small vessel disease

“…For example, overall iron overload could be detected in the tissue, as it has been in some neurodegenerative diseases ( 51 , 52 ). Furthermore, the identification of chronic inflammatory activity ( 53 , 54 ), blood-brain-barrier leakage ( 55 ), and diffuse demyelination ( 56 ) could give better insight into the pathophysiology of CSVD. Due to these possibilities, the last years have seen the surge of a number of open access toolboxes for QSM reconstruction, which will increasingly facilitate the implementation of QSM for clinical purposes ( 57 ).…”