Paramagnetic Rims in Multiple Sclerosis and Neuromyelitis Optica Spectrum Disorder: A Quantitative Susceptibility Mapping Study with 3-T MRI

Abstract

Background and Purpose Iron retained by activated microglia and macrophages in multiple sclerosis (MS) lesions may serve as a marker of innate immune system activation. Among several magnetic resonance imaging (MRI) methods, there has been recent interest in using quantitative susceptibility mapping (QSM) as a potential tool for assessing iron levels in the human brain. This study examined QSM findings in MS and neuromyelitis optica spectrum disorder (NMOSD) lesions obtained with 3-T MRI to assess imaging characteristics related to paramagnetic rims around brain lesions in MS and NMOSD. Methods This study included 32 MS and 21 seropositive NMOSD patients. MRI images were obtained using two 3-T MRI devices (Ingenia, Philips Healthcare; and Magnetom Verio, Siemens Healthineers) during routine diagnosis and treatment procedures. Multi and single echo gradient echo magnitude and phase images were obtained for QSM reconstruction. QSM images were used to characterize the detected lesions, and the findings were compared between MS and NMOSD. Results Totals of 71 and 35 MRI scans were performed during the study period in MS and NMOSD patients, respectively. In QSM images, paramagnetic rims were found in 26 (81.2%) MS patients and 1 (4.8%) NMOSD patient. Eight of the 22 MS patients and only 1 of the 10 NMOSD patients who underwent follow-up MRI showed new paramagnetic rims. The paramagnetic rim lesions appeared after enhancement or in new T2-weighted lesions without enhancement. Conclusions Paramagnetic rims might be a characteristic MRI finding for MS, and therefore they have potential as an imaging marker for differentially diagnosing MS from NMOSD using 3-T MRI.

The prevalence of paramagnetic rim lesions in multiple sclerosis: A systematic review and meta-analysis

“…We emailed 14 study investigators to request additional study data or to seek clarification about study methodology, and 7 kindly replied. Not captured by our search were 5 studies that post-dated our literature search [ 20 , 29 – 32 ]. These were subsequently included in our sensitivity analyses.…”

Magnetic resonance imaging in neuromyelitis optica spectrum disorder

“…Several studies have looked at the use of 7T MR imaging in NMOSD. These studies have shown that the rim-like and nodular pattern of paramagnetic phase changes, suggestive of iron deposition which are seen in some MS brain lesions, are not seen in NMOSD [140][141][142]. No difference in T1 relaxation time between NMOSD and healthy controls has been observed [143].…”

Simultaneous T2 and mapping of multiple sclerosis lesions with radial RARE‐EPI

“…The T 2 and maps derived from 2in1‐RARE‐EPI offer the capacity for the calculation of maps, which is conceptually appealing for probing the spatial distribution of magnetic susceptibility effects 99,100 . This could be beneficial for the assessment of chronic active MS lesions that are characterized by a rim of iron‐enriched activated microglia and macrophages, probing iron levels in the deep gray matter, and for identifying regions of demyelination and iron accumulation during the formation of MS lesions 101 …”

“…99,100 This could be beneficial for the assessment of chronic active MS lesions that are characterized by a rim of iron-enriched activated microglia and macrophages, probing iron levels in the deep gray matter, and for identifying regions of demyelination and iron accumulation during the formation of MS lesions. 101 The potential of the proposed 2in1-RARE-EPI hybrid is not limited to MS lesions or even brain imaging. 2in1-RARE-EPI offers the capacity for simultaneous T 2 and T * 2 mapping in applications dealing with bulk or physiological motion, such as cardiac imaging including myocardial T 2 and T * 2 mapping, [102][103][104] as well as multi-parametric MRI of the eye, kidney, abdomen, and liver.…”