Combining multimodal magnetic resonance brain imaging and machine learning to unravel neurocognitive function in non-neuropsychiatric systemic lupus erythematosus.

OBJECTIVE: To study whether multimodal brain MRI comprising permeability and perfusion measures coupled with machine learning can predict neurocognitive function in young patients with SLE without neuropsychiatric manifestations. METHODS: SLE patients and healthy controls (HCs) (≤40 years of age) underwent multimodal structural brain MRI that comprised voxel-based morphometry (VBM), magnetization transfer ratio (MTR) and dynamic contrast-enhanced (DCE) MRI in this cross-sectional study. Neurocognitive function assessed by Automated Neuropsychological Assessment Metrics was reported as the total throughput score (TTS). Olfactory function was assessed. A machine learning-based model (i.e. glmnet) was constructed to predict TTS. RESULTS: Thirty SLE patients and 10 HCs were studied. Both groups had comparable VBM, MTR, olfactory bulb volume (OBV), olfactory function and TTS. While after correction for multiple comparisons the uncorrected increase in the blood-brain barrier (BBB) permeability parameters compared with HCs did not remain evident in SLE patients, DCE-MRI perfusion parameters, notably an increase in right amygdala perfusion, was positively correlated with TTS in SLE patients (r = 0.636, false discovery rate P < 0.05). A machine learning-trained multimodal MRI model comprising alterations of VBM, MTR, OBV and DCE-MRI parameters mainly in the limbic system regions predicted TTS in SLE patients (r = 0.644, P < 0.0005). CONCLUSION: Multimodal brain MRI demonstrated increased right amygdala perfusion that was associated with better neurocognitive performance in young SLE patients without statistically significant BBB leakage and microstructural abnormalities. A machine learning-constructed multimodal model comprising microstructural, perfusion and permeability parameters accurately predicted neurocognitive performance in SLE patients.

The Effects of Whole-body Cold-water Immersion on Brain Connectivity Related to the Affective State in Adults Using fMRI: A Protocol of a Pre-post Experimental Design.

An emerging body of behavioural studies indicates that regular swimming in cold water has positive effects on mental health and wellbeing, such as reducing fatigue, improving mood, and lessening depressive symptoms. Moreover, some studies reported immediate effects of cold-water immersion (CWI) on elevating mood and increasing a positive emotional state. However, the neural mechanisms underlying these effects remain largely unknown. The lack of studies using neuroimaging techniques to investigate how a whole-body CWI affects neural processes has partly resulted from the lack of a tested experimental protocol. Previous protocols administered tonic limb cooling (1-10 °C) while recording functional magnetic resonance (fMRI) signals. However, using very low water temperature constitutes points of contrast to painful experiences that are different from what we experience after a whole-body head-out CWI. In our protocol, healthy adults unhabituated to cold water were scanned twice: immediately before (pre-CWI) and after (post-CWI) immersion in cold water (water temperature 20 °C) for 5 min. We recorded cardiac and ventilatory responses to CWI and assessed self-reported changes in positive and negative affects. Our protocol showed reliable changes in brain connectivity after a short exposure to cold water, thus enabling its use as a tested experimental framework in future studies.

Short-Term Head-Out Whole-Body Cold-Water Immersion Facilitates Positive Affect and Increases Interaction between Large-Scale Brain Networks.

An emerging body of evidence indicates that short-term immersion in cold water facilitates positive affect and reduces negative affect. However, the neural mechanisms underlying these effects remain largely unknown. For the first time, we employed functional magnetic resonance imaging (fMRI) to identify topological clusters of networks coupled with behavioural changes in positive and negative affect after a 5 min cold-water immersion. Perceived changes in positive affect were associated with feeling more active, alert, attentive, proud, and inspired, whilst changes in negative affect reflected reductions in distress and nervousness. The increase in positive affect was supported by a unique component of interacting networks, including the medial prefrontal node of the default mode network, a posterior parietal node of the frontoparietal network, and anterior cingulate and rostral prefrontal parts of the salience network and visual lateral network. This component emerged as a result of a focal effect confined to few connections. Changes in negative affect were associated with a distributed component of interacting networks at a reduced threshold. Affective changes after cold-water immersion occurred independently, supporting the bivalence model of affective processing. Interactions between large-scale networks linked to positive affect indicated the integrative effects of cold-water immersion on brain functioning.

18F-FDG PET-MRI with T1 MOLLI mapping to detect systemic sclerosis bowel inflammation and fibrosis.

BACKGROUND: Systemic sclerosis-associated gastrointestinal tract involvement (SSc-GIT) is an independent predictor of 2-year mortality in early SSc. Availability of non-invasive investigations will facilitate early diagnosis and monitoring. HYPOTHESIS: We investigate the role of 18F-FDG-PET-MRI in SSc-GIT, hypothesizing that i) higher bowel FDG-PET uptake, a surrogate biomarker for inflammation, distinguishes healthy bowel from inflamed SSc-GIT; ii) MRI T1-MOLLI mapping, a surrogate biomarker for cardiac fibrosis, distinguishes healthy bowel from fibrotic SSc-GIT. METHODS: In this prospective study, 16 SSc patients and 15 healthy controls were recruited. All SSc patients and 5 controls underwent PET-MRI (with T1-MOLLI mapping) on a Siemens 3T mMR; 10 controls underwent MRI without PET. Manual segmentation of the large and small bowels was performed jointly by two trained analysts in order to report T1 and PET values. Control dataset was used to assess normal healthy range. Mean T1 values, mean Tissue-to-Background (TBR) PET values, as well as amount of supposedly abnormal bowel (measured using the healthy ranges) was compared using Student's t-test and Cohen's d effect size. RESULTS: Mean T1 values in large (1113 ±â€¯182 ms vs 856 ±â€¯176 ms; p-value < 0.001) and small bowel (1331 ±â€¯239 ms vs 1169 ±â€¯118 ms; p = 0.02) were higher in SSc patients than controls. 87.5% of the SSc patients' bowel had at least a grade 3 segmental FDG-PET uptake, while no controls showed more than a grade 2 segmental uptake. Patients had higher large bowel mean PET TBR (1.12 ±â€¯0.22) than controls (0.82 ±â€¯0.20, p = 0.02). Using PET and T1 thresholds defined using the control PET-MR data, the percentage of supposedly healthy (non-fibrotic and non-inflamed) tissue was significantly lower in SSc patients (81.1 ±â€¯13.1%) than controls (95.7 ±â€¯3.1%, p = 0.03) for the large bowel. CONCLUSION: Our novel study of FDG-PET-MRI in SSc-GIT demonstrated promising results in non-invasively evaluating concurrently bowel inflammation and fibrosis.