IRCCS San Raffaele Scientific Institute
Neuroimaging Research Unit, Institute of Experimental Neurology, Division of Neuroscience

Presenter Of 1 Presentation

Neuromyelitis Optica and Anti-MOG Disease Oral Presentation

PS16.05 - Application of deep-learning to NMOSD and unclassified seronegative patients

Speakers
Presentation Number
PS16.05
Presentation Topic
Neuromyelitis Optica and Anti-MOG Disease
Lecture Time
13:39 - 13:51

Abstract

Background

Current diagnostic criteria of neuromyelitis optica spectrum disorders (NMOSD) allow the diagnosis of aquaporin-4 (AQP4) seropositive patients with limited manifestations, whereas seronegative patients with limited phenotypes remain unclassified and are usually considered as prodromal phases of multiple sclerosis (MS) or different entities themselves. Nowadays, there is great effort to perform an automatic diagnosis of different neurological diseases using deep-learning-based imaging diagnostics, which is a form of artificial intelligence, allowing predicting or making decisions without a priori human intervention.

Objectives

To provide a deep-learning classification of NMOSD patients with different serological profiles and to compare these results with their clinical evolution.

Methods

228 T2- and T1-weighted brain MRIs were acquired from patients with AQP4-seropositive NMOSD (n=85), early MS (n=95), AQP4-seronegative NMOSD (n=11, 3 with anti-myelin oligodendrocyte glycoprotein antibodies) and unclassified double-seronegative limited phenotypes (n=17 idiopathic recurrent optic neuritis [IRON], n=20 idiopathic recurrent myelitis [IRM]). The latter had a clinical re-evaluation after 4-year follow-up. The neural network architecture was based on four 3D convolutional layers. It was trained and validated on MRI scans (n=180) from AQP4-seropositive NMOSD and MS patients. Then, it was applied to AQP4-seronegative NMOSD and double-seronegative patients with limited phenotypes to evaluate their classification as NMOSD or MS in comparison with their clinical follow-up.

Results

The final algorithm discriminated between AQP-4-seropositive NMOSD and MS with an accuracy of 0.95. Forty-seven/48 (97.9%) seronegative patients were classified as NMOSD (one patient with IRON was classified as MS). Clinical follow-up was available in 27/37 (73%) double-seronegative limited phenotypes: one patient evolved to MS, three developed NMOSD and the others did not change phenotype.

Conclusions

Deep-learning may help in the diagnostic work-up of NMOSD. Our findings support the inclusion of AQP4-seronegative patients to the spectrum of NMO and suggest its enlargement to double-seronegative limited phenotypes.

Collapse

Author Of 2 Presentations

Imaging Poster Presentation

P0637 - Relevance of NODDI to characterise in vivo the microstructural abnormalities of multiple sclerosis cortex and cortical lesions: a 3T study (ID 1087)

Speakers
Presentation Number
P0637
Presentation Topic
Imaging

Abstract

Background

In multiple sclerosis (MS), cortical damage is a relevant predictor of clinical disability, but MRI measures more specific to cortical pathology are needed. Neurite orientation dispersion and density imaging (NODDI) model is a multi-compartment diffusion model to better evaluate the complexity of brain microarchitecture.

Objectives

To characterize, using NODDI, the microstructural abnormalities of normal-appearing cortex (NA-cortex) and cortical lesions (CLs) and their relations with disease phenotypes and clinical disability in a relatively large cohort of MS patients.

Methods

Brain 3D T1-weighted, FLAIR, double inversion recovery (DIR) and diffusion-weighted (DW) sequences were acquired from 164 MS patients (94 relapsing-remitting [RR], 70 progressive [P] MS) and 51 healthy controls (HC). The cortex was segmented from 3D T1-weighted sequence, whereas CLs were quantified on DIR. CLs and NA-cortex masks were then transformed into DW space. Using NODDI, intracellular volume fraction (ICV_f), representing neurite density, extracellular volume fraction (ECV_f) and orientation dispersion index (ODI), reflecting neurite orientation variability, were assessed in NA-cortex and CLs. Between-group comparisons and correlations with clinical and structural MRI measures were investigated.

Results

One hundred and twelve (68.3%) MS patients had ≥1 CL. MS NA-cortex had a significant lower ICV_f vs HC NA-cortex (p=0.001). CLs showed a significant increased ECV_f (p<0.001) and decreased ICV_f and ODI compared to NA-cortex of HC (p<0.001) and MS (p=0.035 and <0.001). Compared to RRMS, PMS had a significant decreased NA-cortex ICV_f (p=0.024). Higher burden of CLs (p<0.001) were found in PMS vs RRMS, without microstructural differences. In MS patients, NA-cortex ICV_f, ECV_f and ODI were significantly correlated with disease duration, EDSS, white matter lesion volumes, CL volumes and whole brain and gray matter atrophy (r from -0.37 to 0.71, p from <0.001 to 0.048).

Conclusions

A significant neurite loss occurs in MS NA-cortex, being more severe with longer disease duration, higher disability and PMS. CLs show a further reduction of neurite density, together with an increased extracellular space, possibly due to inflammation and gliosis, and a reduced ODI suggestive of increased tissue coherence and simplification of neurite complexity. NODDI is reliable and clinically relevant to investigate in vivo the heterogeneous pathological processes affecting MS cortex.

Funding. This study is supported by a senior research fellowship FISM – Fondazione Italiana Sclerosi Multipla – cod. 2019/BS/009 and financed or co-financed with the ‘5 per mille’ public funding.

Collapse
Pathogenesis – Neurodegeneration Poster Presentation

P0953 - Damage of the subventricular zone: relation with striatal atrophy and cognitive performance in MS (ID 1091)

Speakers
Presentation Number
P0953
Presentation Topic
Pathogenesis – Neurodegeneration

Abstract

Background

The subventricular zone (SVZ), a 2-mm layer alongside brain lateral ventricles, is the largest neural stem cells niche in adult humans. It is likely to exert a neuroprotective role on striatal neurons and its damage has been associated with cognitive decline after brain radiation. Multiple sclerosis (MS) can be considered as a disease-related model of SVZ injury, since periventricular lesions involve this region. In MS, cognitive dysfunction is common and information processing speed is affected from the earliest phases of the disease despite relatively low lesion volume (LV) and atrophy.

Objectives

In this study, we characterized SVZ damage in terms of focal lesions and microstructural alterations in MS and assessed its association with striatal atrophy and cognitive dysfunction, evaluated with the Symbol Digit Modalities Test (SDMT).

Methods

3.0 T brain MRI scans were acquired from 97 MS patients and 43 age- and sex-matched healthy controls (HC). After lesion refilling, normalized (N-) brain volumes and cortical thickness (CT) were obtained. According to anatomical references, SVZ mask was segmented on T1-weighted images in the Montreal Neurological Institute space and then registered on fractional anisotropy (FA) and mean diffusivity (MD) maps. Age- and sex-adjusted linear models, partial correlations, and stepwise multiple linear regressions were used to assess SVZ damage and to identify predictors of N-striatal volume and SDMT scores.

Results

In MS, mean SVZ percentage LV was 4.2%. Compared to HC, SVZ normal appearing (NA) tissue was characterized by increased MD (0.89 vs 0.86, p=0.04) and preserved FA values. N-striatal volume correlated with all measures of brain damage (p range: <0.0001-0.02, r absolute values range: 0.24-0.70), while SDMT correlated with SVZ damage (percentage LV, lesional FA , NA MD, p range:0.028-0.0028, r absolute values range: 0.33-0.36) and brain T2-weighted LV (p=0.0051, r=-0.37). N-brain volume (p<0.0001), white matter MD (p=0.0236), SVZ percentage LV (p=0.0052), and mean CT (p=0.0354) were independent predictors of N-striatal volume (R2=0.67). SVZ percentage LV was selected as the only predictor of SDMT performance (p=0.0018, R2=0.26).

Conclusions

SVZ damage is associated with striatal atrophy and cognitive dysfunction in MS. These results might provide a novel key lecture on cognitive impairment in this disease, suggesting a possible role of periventricular injury in MS cognition.

Collapse

Presenter Of 2 Presentations

Neuromyelitis Optica and Anti-MOG Disease Poster Presentation

P0683 - Altered resting state dynamic functional connectivity of precuneus contributes to cognition and depression in neuromyelitis optica spectrum disorders (ID 887)

Speakers
Presentation Number
P0683
Presentation Topic
Neuromyelitis Optica and Anti-MOG Disease

Abstract

Background

In neuromyelitis optica spectrum disorders (NMOSD), cognitive impairment (CI) is nowadays considered as a unique relapse-unrelated manifestation of the disease. As a proof-of-concept, anti-aquaporin4 (AQP4)-IgG seems to inhibit neuronal plasticity and long-term potentiation. Structural and functional MRI (fMRI) studies have disclosed an association with damage of the precuneus (PCUN) and cognitive impairment (CI) in several neurological conditions.

Objectives

To explore the role of dynamic functional connectivity (dFC) of the PCUN at resting state (RS) to explain cognitive alterations in NMOSD patients.

Methods

3.0 T RS fMRI were acquired from 27 AQP4-positive NMOSD patients and 30 age- and sex-matched healthy controls (HC). Patients underwent an extensive neuropsychological evaluation including the assessment of global and domain-specific cognitive impairment index (CII) and Beck Depression Inventory II (BDI-II) scores. DFC of the left (L) and right (R) PCUN was assessed by means of sliding-window seed-voxel correlation analysis. Standard deviation of dFC across windows was used as a measure of dynamicity (the higher the better). Age- and sex-adjusted between-group dFC comparisons and correlations with cognitive scores were assessed using SPM12 and full-factorial models. A p value <0.001 was considered statistically significant.

Results

Compared to HC, NMOSD patients had reduced L-PCUN dFC with caudate nucleus, rectus, olfactory bulb and occipital inferior gyrus and increased dFC between the L-PCUN and the middle temporal gyrus and between the R-PCUN the middle occipital gyrus. Global CII positively correlated with higher L-intra-PCUN dFC, as well as with higher dFC between the L-PCUN and the middle temporal and middle frontal gyrus and between the R-PCUN and the middle cingulate gyrus. Impairment of information processing speed (IPS, 59.2%) and depression (63.0%) were the most common cognitive alterations. The IPS index positively correlated with a higher L-intra-PCUN-dFC, and a higher dFC between the R-PCUN and the middle cingulate gyrus. The BDI-II score positively correlated with a higher dFC between the R-PCUN and the middle frontal gyrus.

Conclusions

The assessment of PCUN dFC supports the role of PCUN in NMOSD cognitive dysfunction. We observed a protective effect of higher dynamic connections with limbic regions for cognitive performance, while those with the frontal lobe were detrimental for depressive symptoms.

Collapse
Pathogenesis – the Blood-Brain Barrier Poster Presentation

P0982 - MR T2-relaxation time as an indirect measure of brain water accumulation in Neuromyelitis Optica Spectrum Disorders (ID 1077)

Speakers
Presentation Number
P0982
Presentation Topic
Pathogenesis – the Blood-Brain Barrier

Abstract

Background

One of the main unsolved issues in the clinical management of neuromyelitis optica spectrum disorders (NMOSD) is the lack of biomarkers predicting short-term relapses. In physiological conditions, the blood brain barrier (BBB) protects the CNS from water unbalance, with aquaporin-4 (AQP4) water channels on astrocytes podocytes being the main regulator of water influx and efflux. In NMOSD, BBB integrity might be threatened by the presence of antibodies targeting AQP4 water channels and triggering complement-mediated astrocytes damage. In line with this, increased T2-signal in acute lesions (“bright spotty lesions”) is considered specific for NMOSD. However, it remains unexplored whether these patients present a chronic water unbalance.

Objectives

To provide an indirect estimation of brain water content in NMOSD by measuring T2-relaxation time (T2rt) and to assess whether it differs in patients having a short-term relapse.

Methods

In this multicenter MR study, T2rt was calculated from brain dual echo turbo spin echo images assuming a mono exponential decay. T2rt maps of normal appearing white matter (NAWM), gray matter (GM) and basal ganglia were obtained from 77 AQP4-positive NMOSD and 84 HC. Short-term relapses were defined as those occurring within one month before or after MRI scan. Differences between NMOSD and HC were assessed with age-, sex- and site-adjusted linear models. ROC analyses were run to identify discriminators between stable and short-term relapsing patients.

Results

NMOSD patients and HC had similar ages. Compared to HC, T2rt was increased in the GM (103 vs 97 ms), NAWM (88 vs 84 ms) and putamen (75 vs 72 ms) of NMOSD patients (p<0.001 for all). Short-term relapses occurred in 20/77 (26%) of patients. According to ROC analysis, T2rt cut-offs of 87 ms in the NAWM, 87 ms in the thalamus and 88 ms in the caudatus were able to discriminate between short-term relapsing and stable patients with good accuracy (AUC=0.70, 0.76 and 0.79 respectively, p≤ 0.027).

Conclusions

NMOSD patients had increased T2rt values, in line with the hypothesis of subclinical water accumulation in this disorder. The burden of T2rt alterations might be useful for identifying those patients with incipient or recent relapses.

Collapse