One model to unite them all: Personalized federated learning of multi-contrast MRI synthesis.

Curation of large, diverse MRI datasets via multi-institutional collaborations can help improve learning of generalizable synthesis models that reliably translate source- onto target-contrast images. To facilitate collaborations, federated learning (FL) adopts decentralized model training while mitigating privacy concerns by avoiding sharing of imaging data. However, conventional FL methods can be impaired by the inherent heterogeneity in the data distribution, with domain shifts evident within and across imaging sites. Here we introduce the first personalized FL method for MRI Synthesis (pFLSynth) that improves reliability against data heterogeneity via model specialization to individual sites and synthesis tasks (i.e., source-target contrasts). To do this, pFLSynth leverages an adversarial model equipped with novel personalization blocks that control the statistics of generated feature maps across the spatial/channel dimensions, given latent variables specific to sites and tasks. To further promote communication efficiency and site specialization, partial network aggregation is employed over later generator stages while earlier generator stages and the discriminator are trained locally. As such, pFLSynth enables multi-task training of multi-site synthesis models with high generalization performance across sites and tasks. Comprehensive experiments demonstrate the superior performance and reliability of pFLSynth in MRI synthesis against prior federated methods.

The effect of SARS-CoV-2 virus on resting-state functional connectivity during adolescence: Investigating brain correlates of psychotic-like experiences and SARS-CoV-2 related inflammation response.

We first aimed to investigate resting-state functional connectivity (rs-FC) differences between adolescents exposed to SARS-CoV-2 and healthy controls. Secondly, the moderator effect of PLEs on group differences in rs-FC was examined. Thirdly, brain correlates of inflammation response during acute SARS-CoV-2 infection were investigated. Eighty-two participants aged between 14 and 24 years (SARS-CoV-2 (n = 35), controls (n = 47)) were examined using rs-fMRI. Seed-based rs-FC analysis was performed. The positive subscale of Community Assessment of Psychotic Experiences-42 (CAPE-Pos) was used to measure PLEs. The SARS-CoV-2 group had a lesser rs-FC within sensorimotor network (SMN), central executive network (CEN) and language network (LN), but an increased rs-FC within visual network (VN) compared to controls. No significant differences were detected between the groups regarding CAPE-Pos-score. However, including CAPE-Pos as a covariate, we found increased rs-FC within CEN and SN in SARS-CoV-2 compared to controls. Among the SARS-CoV-2 group, neutrophil/lymphocyte and thrombocyte*neutrophil/lymphocyte ratio was correlated with decreased/increased FC within DMN and SN, and increased FC within CEN. Our results showed rs-FC alterations within the SMN, CEN, LN, and VN among adolescents exposed to SARS-CoV-2. Moreover, changes in rs-FC associated with PLEs existed in these adolescents despite the absence of clinical changes. Furthermore, inflammation response was correlated with alterations in FC within the triple network system.

IgG4-related pachymeningitis-Long term follow up and outcome of six patients.

OBJECTIVE: Our understanding of IgG4-RD and pachymeningitis has grown substantially, but the optimal approach for diagnosis, management, and long-term outcomes is still an area of uncertainty. METHODS: HUVAC is a database for IgG4-RD patients, this database was retrospectively evaluated for pachymeningeal disease. Demographic, clinical, serological, imaging, histopathological data, and treatment details were re-interpreted in patients with pachymeningitis. RESULTS: Among 97 patients with IgG4-RD, 6 (6.2%) had pachymeningitis. None of these patients had extracranial features, and also, in most of the patients, serum IgG4 levels were normal. Tentorium cerebelli and transverse sinus dura were the most commonly involved in the posterior fossa. During 18 months of median follow-up on steroid+-rituximab, none of them relapsed as pachymeningitis. CONCLUSION: Our patients were mainly older males with sole neurological involvement. Non-specific headache was the most common manifestation, and serum IgG4 levels were not useful for diagnosis. Typical radiology and tentorial thickening should suggest IgG4-RD and prompt an early biopsy. Moreover, accompanying hypophysitis could also be a clue. With steroids+ rituximab treatment, no relapse related to meningeal involvement was seen in long-term follow-up.

Targeted resequencing reveals high-level mosaicism for a novel frameshift variant in WDR45 associated with beta-propeller protein-associated neurodegeneration.

OBJECTIVES: Beta-propeller protein-associated neurodegeneration (BPAN) is a rare X-linked dominant neurodegenerative disease, which is characterized by iron accumulation in the basal ganglia. BPAN is associated with pathogenic variation in WDR45, which has been reported almost exclusively in females most probably due to male lethality in the hemizygous state. METHODS: Whole exome sequencing (WES) and targeted deep sequencing were performed for a male with a clinical diagnosis of BPAN at the age of 37. RESULTS: The novel frameshift variant in WDR45 detected by WES was further analyzed with targeted resequencing to detect a mosaic variant with a level of 85.5% in the blood sample of the proband. DISCUSSION: Although the main role of WDR45 remains elusive, recent studies show that WDR45 may contribute to neurodegeneration through defects in autophagy, iron storage and ferritin metabolism, mitochondria organization, and endoplasmic reticulum homeostasis. The extend of spatiotemporal haploinsufficiency of WDR45 frameshifting variants caused by mosaicism in males may lead to variable clinical severity, which may be hard to elaborate clinically. Promising genetic analysis strategies using targeted deep sequencing may help determine the clinical outcome of somatic mosaicism in neurological disorders including BPAN. Additionally, we suggest that deep sequencing should be conducted in cerebrospinal fluid samples to provide more reliable results in terms of reflecting the mosaicism level in the brain for future studies.

A diffusion tensor imaging study in schizophrenia patients with clozapine induced obsessive compulsive symptoms.

OBJECTIVE: The aim of this study was to evaluate brain connectivity by diffusion tensor imaging (DTI) in schizophrenia patients with clozapine-induced obsessive compulsive symptoms (OCS). METHODS: Eighteen schizophrenia patients, nine of which had clozapine-induced OCS (Clz-OCS (+)), 9 without OCS (Clz-OCS (-)) and 9 healthy controls were included. Psychopathology was evaluated with Positive and Negative Syndrome Scale and Yale-Brown Obsession and Compulsion Scale in the patient groups. All groups were assesed with neurocognitive tests and DTI. RESULTS: Tract-Based Spatial Statistics based comparison of DTI revealed lower fractional anisotropy in the genu of corpus callosum (CC), right cingulum, left frontal white matter (WM) in the Clz-OCS (+) group, compared to controls. Fractional anisotropy was found to be lower in the bilateral occipital WM and higher in the bilateral medial temporal regions, anterior limb of internal capsule, cingulum, frontoparietal peripheral WM, right external capsule and genu of CC in Clz-OCS (+) patients compared to Clz-OCS (-). CONCLUSIONS: WM integrity in several pathways such as cortico-striato-thalamo-cortical circuitry and orbito-frontal tracts seems to be affected differently in patients with Clz-OCS (+). Different neuroplastic effects of clozapine leading to occurrence of OCS in a subgroup of patients is possible, and needs further evaluation by longitudinal follow-up studies.

Claude Syndrome in Childhood Associated with Probable Neuro-Behcet Disease.

Claude syndrome is a rare midbrain stroke syndrome characterized by ipsilateral third cranial nerve palsy and contralateral hemiataxia. So far, only a few cases have been reported in childhood. We present two children with Claude syndrome at 9 and 15 years of age. The typical clinical picture was consistent with brain magnetic resonance imaging findings. A thorough investigation regarding the underlying etiology revealed no definite diagnosis but clues suggestive of probable neuro-Behcet disease. Awareness of pediatric neurologists on arterial ischemic stroke has been increasing over the past decades, enabling timely diagnosis and appropriate management of rare childhood cases with midbrain stroke.

Assessment of glymphatic function in narcolepsy using DTI-ALPS index.

INTRODUCTION: Sleep is a modulator of glymphatic activity which is altered in various sleep disorders. Narcolepsy is a sleep disorder characterized by excessive daytime sleepiness (EDS), rapid onset of rapid eye movement (REM) sleep, cataplexy, disturbed night sleep with fragmentation. It is categorized into two types, type 1 (NT1) and type 2 (NT2) depending on the presence of cataplexy and/or absence of orexin. We sought for alterations in glymphatic activity in narcoleptic patients using diffusion tensor imaging (DTI) along perivascular space (ALPS) index on magnetic resonance imaging (MRI). MATERIAL AND METHODS: Adult patients diagnosed with NT1 or NT2 who had polysomnography (PSG) and MRI with DTI were included in the study. Sleep recording included Epworth Sleepiness Scale (ESS) score, sleep latency during multiple sleep latency test (MSLT), sleep efficiency during night PSG, wake after sleep onset (WASO), REM sleep latency during PSG, percentage of non-REM (NREM), REM sleep and wakefulness during night PSG. DTI-ALPS index was calculated for each patient and age-sex matched healthy control(HC)s. RESULTS: The study group was composed of 25 patients [F/M = 15/10, median age = 34 (29.5-44.5)], 14 with NT1 and 11 with NT2 disease. ESS, WASO and percentage of wakefulness were significantly higher in NT1 patients (p < 0.05). Mean DTI-ALPS was not significantly different neither between narcoleptic patients and HCs, nor between NT1 and NT2 patients (all, p > 0.05). However, DTI-ALPS was negatively correlated with WASO (r = -0.745, p = 0.013) and percentage of wakefulness (r = -0.837, p = 0.005) in NT1 patients. DTI-ALPS correlated negatively with percentage of N1 sleep (r = -0.781, p = 0.005) but positively with REM percentage (r = 0.618, p = 0.043) in NT2 patients. CONCLUSION: In this study, DTI-ALPS was not significantly different in narcoleptic patients than the HCs. However, the glymphatic index as assessed by DTI-ALPS correlated with PSG parameters; negatively with WASO, percentage of wakefulness in NT1, percentage of N1 sleep in NT2, and positively with REM sleep in NT2. A tendency for a reduction in DTI-ALPS in NT1 patients compared to both NT2 patients and HCs was also found. These findings might show the first evidence of an alteration of glymphatic activity, especially in NT1 patients, thus warrant further prospective studies in larger size of narcoleptic patient cohorts.

An Unusual Pattern of Skull Base Pneumatization.

OBJECTIVE: Our aim is to describe an unusual pattern of craniocervical pneumatization resulting in a spontaneous fracture in a patient, who presented with tinnitus. METHODS: Temporal CT was ordered in a patient with tinnitus lasting over a year. His audiogram was normal. No history of previous trauma, recent flight, diving, or weight lifting was present. Further questioning revealed his habitual Valsalva maneuvers to relieve symptoms of nasal congestion. RESULTS: Temporal CT showed abnormal pneumatization of the occipital bone and C1 vertebra. A definite cortical defect resulted with the presence of air around the neighboring soft tissues. The emphysema was most prominent in the suboccipital fossa but it was also seen in the epidural space of the spinal canal. CONCLUSION: Abnormal pneumatization of the skull base and cervical vertebra can be symptomatic due to its tendency to fracture. The presumed cause of pneumatization in this patient is habitual Valsalva maneuvers.

Increased ocular wall thickness and decreased globe volume in children with mucopolysaccharidosis type VI.

PURPOSE lthough clinical ophthalmologic findings have been reported, no study documented magnetic resonance imaging (MRI) findings in mucopolysaccharidosis (MPS) type VI. The aim of this study was to determine the ophthalmologic imaging findings of MPS type VI in the pediatric age group retrospectively. METHODS Brain MRIs of 10 patients with MPS type VI and 49 healthy children were evaluated independently by two pediatric radiologists for the following characteristics: globe volume, ocular wall thickness, and optic nerve sheath diameter for each orbit. The means of the measurement of each group were compared by using an independent t-test. Agreement and bias between reviewers were assessed by intra-class correlation coefficients (ICC). RESULTS A total of 59 children [32 girls (54.23%), 27 boys (45.77%); age range, 4-16 years; mean age, 10.37 ± 3.73 years] were included in the study. Statistical analysis revealed smaller eyeballs and thicker ocular walls of patients with MPS type VI (P < .001 and P < .001, respectively). However, there was no statistically significant difference in terms of optic nerve sheath diameter between the two groups (P=.648). CONCLUSION Patients with MPS type VI displayed reduced globe volumes and increased ocular wall thicknesses compared to the healthy children. Therefore, we recommend that ophthalmologic imaging findings might prove to be an auxiliary tool in the diagnosis of MPS patients.

Imaging spectrum of extracorporeal membrane oxygenation related neurologic events in children.

BACKGROUND: Extracorporeal membrane oxygenation (ECMO) can be associated with severe neurological complications increasing morbidity and mortality. We aimed to evaluate imaging findings in patients with neurological complications associated with ECMO. METHODS: Children ( < 18 years) who had ECMO support and received cross-sectional imaging (cranial CT and/ or MRI) were retrospectively evaluated. Age, gender, clinical and imaging findings were documented and the relation to ECMO duration and survival rates with imaging findings and imaging time (during ECMO or after weaning) were examined. RESULTS: Twenty children who had cranial CT/MRI during (n=6) ECMO and after weaning (n=14) were included in the study. The median duration of ECMO was 12.5 days (IQR=5-25 days) with a survival rate of 65%. Fourteen patients had positive imaging findings including ischemic stroke (n=4), hemorrhagic stroke (n=4), hypoxicischemic encephalopathy (n=2), posterior reversible encephalopathy syndrome (PRES) (n=3) and cerebral vein thrombosis (n=1). The duration of ECMO and survival rates did not significantly differ between patients with positive and unremarkable imaging findings. However, the survival rate was significantly higher (p < 0.001) and the duration of ECMO was significantly lower in patients scanned after weaning compared to patients imaged during ECMO support (p=0.033). CONCLUSIONS: Our series revealed PRES in ECMO-related neurologic events in addition to commonly reported thrombotic and hemorrhagic stroke in the literature. Availability of cross-sectional imaging and awareness of radiologists to these complications during ECMO or after weaning help in prompt diagnosis and treatment.