Background

Clinical and imaging features of myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) may overlap with those of aquaporin 4-neuromyelitis optica spectrum disorder (AQP4-NMOSD) and relapsing remitting multiple sclerosis (RRMS). There is an unmet need for MRI biomarkers which reflect biological mechanisms involved in MOGAD and can help in the differential diagnosis.

Objectives

We aim to identify imaging features able to differentiate between non-acute MOG-antibody disease, AQP4-NMOSD and RRMS.

Methods

In this ongoing retrospective, cross-sectional MAGNIMS study, we analyzed data collected from 8 centers. All subjects (n=352) had brain and cervical cord 3T MRI. Quantification of MRI biomarkers included brain white matter lesions (WMLs), cortical lesions (CL), brain parenchymal fraction (BPF), white matter fraction (WMF), cortical and deep grey matter fractions (GMF) and cross-sectional cervical cord area (CSA) at C1-C2. Linear regression models were used to compare MRI measures between groups, corrected for age, sex, and centre. Statistical significance was considered when p was <0.05.

Results

91 patients with MOGAD (50F, mean age: 41yrs [±15]), 85 with AQP4-NMOSD (68F, 49yrs [±14]), 90 with RRMS (56F, 41yrs [±11]) and 87 healthy controls (HCs) (54F, 36yrs [±11.6]) were collected. The most common phenotypes at onset were optic neuritis and transverse myelitis in MOGAD (93%) and AQP4-NMOSD (87%). WMLs were detected in 57% MOGAD, 79% AQP4-NMOSD, all RRMS (100%) patients, and in 15% HCs. The mean lesion load and number of lesions were higher in RRMS than both MOGAD (p=0.007, p<0.001) and AQP4-NMOSD (p=0.001, p<0.001). At least one CL was seen in 8% patients with MOGAD (total n=8), 10% patients with AQP4-NMOSD (n=7), and in 69% patients with RRMS (n=150). All patient groups showed lower BPF than HCs, with lower WMF in MOGAD and RRMS than HCs (all p<0.01). Between groups, deep GMF was lower in RRMS than MOGAD (p<0.001) and AQP4-NMOSD (p=0.001). CSA was reduced in all disease groups when compared to HCs (all p<0.01) and lower in AQP4-NMOSD than RRMS (p=0.01).

Conclusions

This ongoing study indicates that MOGAD and AQP4-NMOSD share similar MRI features, and no specific MRI biomarker can distinguish between them. Patients with AQP4-NMOSD showed greater spinal cord atrophy than RRMS, and RRMS patients had a higher number of cortical lesions, and greater deep GM atrophy than AQP4-NMOSD and MOGAD. The next step is to investigate whether lesion distribution differs between the two antibody-mediated disease.

Background

Inflammatory demyelination in the anterior optic pathway, including the optic chiasm (OC), occurs frequently in relapsing-remitting multiple sclerosis (RRMS), aquaporin4 (AQP4) antibody (Ab) positive neuromyelitis optica spectrum disorder (NMOSD), and myelin oligodendrocyte glycoprotein-Ab associated-disease (MOGAD).

Objectives

To evaluate the involvement of the OC in RRMS, AQP4-NMOSD and MOGAD using Magnetization Transfer Ratio (MTR) and explore its relationship with prior optic neuritis (ON).

Methods

We recruited 25 patients with RRMS (16 F, mean age: 44.6 yrs ±11.8, median EDSS: 2.0 [range: 1.0-7.5], mean number of previous episodes of ON: 0.44±0.58, 9 unilateral, 1 bilateral), 13 with AQP4-NMOSD (10 F, mean age: 45.3 yrs ±11.2, median EDSS: 3.0 [1.0-6.5], mean number of ON episodes: 1.54±1.13, 4 unilateral, 6 bilateral), 20 with MOGAD (13 F, mean age: 33.9 yrs ±16.4, median EDSS: 2.0 [0.0-6.5], mean number of ON episodes: 2.85±2.80, 6 unilateral, 11 bilateral) and 29 healthy controls (HC) (23 F, mean age: 35.9 yrs ±12.8). We used T2-weighted, MTon and MToff images to obtain MTR maps of the OC. Age-, sex-, and disease duration-adjusted linear regression models were used to compare the measures between disease and healthy groups (p<0.05).

Results

Chiasmal MTR values in patients with previous ON were lower in AQP4-NMOSD (p=0.040) and MOGAD (p=0.001) than HC but not when compared to patients without previous ON. In patients with RRMS and previous ON, MTR values were lower than patients without prior ON (p=0.003). No differences were found either between patients without ON and HC or between the disease groups.

When considering all patients with demyelinating diseases, patients with previous ON had lower chiasmal MTR values when compared to HC (unilateral: p=0.037; bilateral: p=0.002) and to patients without ON (unilateral: p=0.019; bilateral: p<0.001). This difference persisted when comparing both monophasic and relapsing ON patients to HC (p=0.044; p<0.001) and to patients without ON (p=0.019; p<0.001). No differences were found between patients without history of ON and HC. A correlation was found between MTR values and number of ON episodes (rho=-0.55, p<0.001).

Conclusions

Microstructural damage in the OC correlated with the number of ON episodes across inflammatory demyelinating diseases. A higher number of episodes is associated with lower chiasmal MTR, supporting its role as an accessible target for the assessment of the visual pathway in inflammatory diseases.

Background

Inflammatory demyelination in the anterior optic pathway, including the optic chiasm (OC), occurs frequently in relapsing-remitting multiple sclerosis (RRMS), aquaporin4 (AQP4) antibody (Ab) positive neuromyelitis optica spectrum disorder (NMOSD), and myelin oligodendrocyte glycoprotein-Ab associated-disease (MOGAD).

Objectives

To evaluate the involvement of the OC in RRMS, AQP4-NMOSD and MOGAD using Magnetization Transfer Ratio (MTR) and explore its relationship with prior optic neuritis (ON).

Methods

We recruited 25 patients with RRMS (16 F, mean age: 44.6 yrs ±11.8, median EDSS: 2.0 [range: 1.0-7.5], mean number of previous episodes of ON: 0.44±0.58, 9 unilateral, 1 bilateral), 13 with AQP4-NMOSD (10 F, mean age: 45.3 yrs ±11.2, median EDSS: 3.0 [1.0-6.5], mean number of ON episodes: 1.54±1.13, 4 unilateral, 6 bilateral), 20 with MOGAD (13 F, mean age: 33.9 yrs ±16.4, median EDSS: 2.0 [0.0-6.5], mean number of ON episodes: 2.85±2.80, 6 unilateral, 11 bilateral) and 29 healthy controls (HC) (23 F, mean age: 35.9 yrs ±12.8). We used T2-weighted, MTon and MToff images to obtain MTR maps of the OC. Age-, sex-, and disease duration-adjusted linear regression models were used to compare the measures between disease and healthy groups (p<0.05).

Results

Chiasmal MTR values in patients with previous ON were lower in AQP4-NMOSD (p=0.040) and MOGAD (p=0.001) than HC but not when compared to patients without previous ON. In patients with RRMS and previous ON, MTR values were lower than patients without prior ON (p=0.003). No differences were found either between patients without ON and HC or between the disease groups.

When considering all patients with demyelinating diseases, patients with previous ON had lower chiasmal MTR values when compared to HC (unilateral: p=0.037; bilateral: p=0.002) and to patients without ON (unilateral: p=0.019; bilateral: p<0.001). This difference persisted when comparing both monophasic and relapsing ON patients to HC (p=0.044; p<0.001) and to patients without ON (p=0.019; p<0.001). No differences were found between patients without history of ON and HC. A correlation was found between MTR values and number of ON episodes (rho=-0.55, p<0.001).

Conclusions

Microstructural damage in the OC correlated with the number of ON episodes across inflammatory demyelinating diseases. A higher number of episodes is associated with lower chiasmal MTR, supporting its role as an accessible target for the assessment of the visual pathway in inflammatory diseases.