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

Author Of 5 Presentations

Imaging Poster Presentation

P0608 - MRI-based clustering of MS patients in the perspective of personalized medicine (ID 1075)

Speakers
Presentation Number
P0608
Presentation Topic
Imaging

Abstract

Background

Multiple sclerosis (MS) patients have heterogeneous clinical manifestations, natural history, and treatment response, due to heterogeneous underlying pathophysiological differences.

Objectives

To find clusters of MS patients with homogeneous underlying pathophysiology, as determined by advanced MRI techniques.

Methods

One-hundred-and-fifteen MS (57 relapsing-remitting, 12 primary- and 46 secondary-progressive) patients, and 44 age- and sex-matched healthy controls (HC) underwent brain and cervical cord 3T MRI with pulse sequences for assessing lesions, atrophy, and microstructural damage (with diffusion-tensor metrics). A complete neurological assessment, with rating of Expanded Disability Status Scale (EDSS) was also performed. Clusters of MS patients were identified with hierarchical clustering on age- and sex-adjusted MRI variables.

Results

Five clusters of MS patients were identified: “early”; “intermediate-cord”, “intermediate-cortical”, “intermediate-late-lesion”; and “late”. “Early” patients showed similar MRI metrics vs HC (except lesions), low EDSS and short disease duration (DD). “Intermediate” groups had altered MRI metrics, higher EDSS and longer DD, compared to “early” (p<0.01). “Intermediate-cord” patients were characterized by high cord T2-lesion volume (LV) (p<0.001 vs all but “late” groups), and “intermediate-cortical” by low cortical thickness (p<0.001 vs all but “intermediate-late-lesion” and “late” groups). “Intermediate-late-lesion” patients showed higher brain T2-LV and deep grey matter (GM) atrophy, but also a longer DD, compared to all but “late” groups (p<0.01). “Late” patients had higher EDSS and DD, compared to “intermediate-cord” and “intermediate-cortical” (p<0.01); and worst corticospinal-tract diffusion-tensor metrics and cord/brain atrophy (p<0.01 vs all). “Intermediate-cord” patients could be divided into 2 groups with similar DD characterized by different cord GM atrophy and cortical thickness (p<0.01), the more impaired one including mostly progressive phenotypes and higher EDSS.

Conclusions

MRI-based clustering of MS patients is feasible. It contributes to demonstrate disease heterogeneity and in the future it may be useful for personalized medicine. “Intermediate-cord” patients may be the best target to study neuroprotective and regenerative strategies.

Funding: Partially supported by grants from Fondazione Italiana Sclerosi Multipla (FISM/2018/R/16).

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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.

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Neuropsychology and Cognition Poster Presentation

P0830 - Unraveling the substrates of cognitive impairment in multiple sclerosis: the contribution of a multiparametric structural and functional MRI approach (ID 1081)

Speakers
Presentation Number
P0830
Presentation Topic
Neuropsychology and Cognition

Abstract

Background

Cognitive impairment (CI) affects up to 70% of multiple sclerosis (MS) patients. Although several magnetic resonance imaging (MRI) correlates of CI have been suggested, their relative contribution to explain CI requires further investigation.

Objectives

To evaluate the combined contribution of white matter (WM) lesions, gray matter (GM) atrophy and resting state (RS) functional (f) MRI abnormalities in explaining CI in a large cohort of MS patients.

Methods

Brain 3T dual-echo, 3D T1-weighted and RS fMRI scans were acquired from 100 healthy controls (HC) and 276 MS patients. All MS patients underwent the Rao’s battery. CI was defined by ≥2 tests with a z-score<-1.5. Distribution of brain WM lesions, GM atrophy and RS functional connectivity (FC) abnormalities within the default mode (DMN) and salience (SN) networks were compared between HC and MS patients at a voxel level. Using sex-, age- and phenotype-adjusted stepwise logistic regression models, the role of WM lesions (model 1), GM atrophy (model 2), RS FC (model 3) and their combination (model 4) in explaining CI was investigated. Model performances were assessed by the area under the curve (AUC).

Results

Eighty-three MS patients had CI. In model 1, lesions in left (L) superior longitudinal fasciculus (SLF) (odds ratio [OR]=1.84), L medial lemniscus (OR=1.79) and L inferior longitudinal fasciculus (OR=1.57) predicted CI (p≤0.009). In model 2, L precuneus (OR=0.52) and L caudate (OR=0.56) volumes predicted CI (p≤0.007). In model 3, increased RS FC in L caudate (DMN) (OR=1.77) and decreased RS FC in right (R) thalamus (DMN) (OR=0.66) and L inferior frontal gyrus (IFG) (SN) (OR=0.68) predicted CI (p≤0.02). In model 4, R middle cerebellar peduncle (OR=2.05) and L SLF (OR=1.84) lesions, L precuneus atrophy (OR=0.46), increased RS FC in L caudate (DMN) (OR=1.64), and decreased RS FC in L IFG (SN) (OR=0.64) predicted CI (p≤0.02). Compared to demographic and clinical variables only (AUC=0.73), the separate models performed significantly better (AUC=0.82, 0.81 and 0.80, respectively, p≤0.003), with model 4 having the best performance (AUC=0.86, p<0.001).

Conclusions

The combination of multiparametric MRI techniques contributes to better understand the structural and functional substrates of cognitive dysfunction in MS patients. The accumulation of focal WM lesions and GM atrophy in strategic brain regions together with maladaptive functional mechanisms explains CI in MS.

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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.

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Pediatric MS Poster Presentation

P1070 - Age at disease onset influences grey matter and white matter integrity in MS (ID 1070)

Speakers
Presentation Number
P1070
Presentation Topic
Pediatric MS

Abstract

Background

Natural history studies demonstrated clinical phenotype and course of multiple sclerosis (MS) are age-dependent. The comparison of pediatric (POMS) vs adult onset (AOMS) MS patients is a useful model for studying the effects of age on MS pathophysiology.

Objectives

To determine whether age of disease onset influences the extent, distribution and trajectories of development of brain grey matter volume (GMV) and white matter (WM) microstructural abnormalities in adult MS patients.

Methods

Sixty-seven POMS (40 females; age 30±9, range 18–53) and 143 sex- and disease duration-matched AOMS (85 females; age 46±11, range 20 – 70) patients, together with 208 age- and sex-matched healthy controls (HC) (120 females; age 37±14, range 18–70), underwent neurological examination (with Expanded Disability Status Scale [EDSS] scoring) and MRI acquisition on a 3T scanner, including dual echo, 3D T1-weighted, and diffusion-weighted sequences. T2-lesion volumes, GMV and WM fractional anisotropy (FA) were derived and standardized based on distribution in HC, to remove the effects of age and sex. Linear models were used to study associations with disease duration in POMS and AOMS patients. Time to reach clinical and radiological milestones was assessed with the product-limit approach.

Results

At disease duration=1year, GMV and WM FA were not abnormal in POMS, while they were already compromised in AOMS patients (p ranging from 0.04 to <0.001) compared to HC. Significant interaction of age at onset (POMS vs AOMS) into the association with disease duration was found for GMV (p=0.01) and WM FA (p=0.04). The crossing point of regression lines in POMS and AOMS was at 19 and 15 years of disease duration for GMV and WM FA, respectively. Median disease duration to reach EDSS=3 was 29 years for POMS and 19 years for AOMS patients (p<0.001), to reach brain GM volume z-score=-1.645 was 24 years for POMS and 19 years for AOMS (p=0.04), and to reach brain WM FA z-score=-1.645 was 19 years for POMS and 17 years for AOMS (p=0.31).

Conclusions

In POMS patients, disruption of WM integrity precedes GM damage and is initially less severe than in AOMS. The rate of WM damage accumulation is higher in POMS compared to AOMS, resulting in more severe WM damage with longer disease duration. Except for WM damage, POMS patients reach clinical and MRI milestones at younger age than AOMS, but take longer time.

Funding. Partially supported by grants from Italian Ministry of Health (GR-2009-1529671) and Fondazione Italiana Sclerosi Multipla (FISM2016/R/23).

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