An analysis-ready and quality controlled resource for pediatric brain white-matter research

We created a set of resources to enable research based on openly-available diffusion MRI (dMRI) data from the Healthy Brain Network (HBN) study. First, we curated the HBN dMRI data (N = 2747) into the Brain Imaging Data Structure and preprocessed it according to best-practices, including denoising and correcting for motion effects, susceptibility-related distortions, and eddy currents. Preprocessed, analysis-ready data was made openly available. Data quality plays a key role in the analysis of dMRI. To optimize QC and scale it to this large dataset, we trained a neural network through the combination of a small data subset scored by experts and a larger set scored by community scientists. The network performs QC highly concordant with that of experts on a held out set (ROC-AUC = 0.947). A further analysis of the neural network demonstrates that it relies on image features with relevance to QC. Altogether, this work both delivers resources to advance transdiagnostic research in brain connectivity and pediatric mental health, and establishes a novel paradigm for automated QC of large datasets

Effectiveness of fast mapping to promote learning in schizophrenia

Fast mapping (FM), a process that promotes the expeditious incidental learning of information, is thought to support rapid vocabulary acquisition in young children through extra-medial temporal lobe (MTL) regions. A recent study suggested that patients with MTL damage resulting in profound amnesia were able to learn novel word–image associations using an FM paradigm. The present study investigated whether FM would be an effective strategy to promote learning for individuals with schizophrenia, a severe mental illness associated with compromised MTL functionality. Twenty-five patients with schizophrenia and 27 healthy control subjects completed trials of incidental FM encoding (experimental condition) and explicit encoding (EE, control condition) over the course of three visits spaced one week (±2 days) apart. All participants were evaluated for recognition 10 min after each encoding condition was presented, and again one week (±2 days) later. Results indicate that both groups performed better on the EE recognition trials when compared to FM (p's < 0.05). For the FM recognition trials, both groups performed similarly. However, participants with schizophrenia performed significantly worse on the EE recognition trials than healthy control participants (p's < 0.05). While participants with schizophrenia did not perform significantly worse when assessed for FM recognition, these results do not provide enough evidence to suggest that FM facilitates learning to a greater extent in schizophrenia when compared to EE. Whether FM may benefit a subgroup of patients with schizophrenia remains a focus of further investigation

Nanosized free radicals for the use as contrast and hyperpolarization agents in ultralow-field and high-field MRI

Introduction Overhauser MRI is a technique, which could enable in vivo magnetic resonance experiments at low (100 can be achieved. This technique requires a stable free electron source in mM concentrations, usually in the form of free radicals. To enhance the stability of free radicals one can use nanosized carrier molecules. Here, we present cyclodextrines as carriers for nitroxide free radicals. The Overhauser DNP performance as well as toxicity and stability are tested. Methods We tested biotin, avidin, dendrimers, liposomes and cyclodextrines as carriers for different nitroxide free radicals. To assess the ODNP performance, the maximum enhancement Emax and the RF power P1/2, needed to reach Emax/2, were measured at 2 mM concentration (a reasonable concentration for in vivo experiments) in a homemade ULF MRI system. The stability of the selected nitroxides in the aforementioned carriers was tested in ascorbic acid solution and whole blood using EPR and ULF NMR spectroscopy. Cell viability was monitored on rat astrocyte cell cultures using the MTT assay and propidium iodide (PI) staining. Results obtained from probes with and without carriers were compared for commercially available nitroxides 3CP, 3CxP and TEMPOL and synthesized nitroxides. Results/Discussion Except for cyclodextrines all other carrier systems showed poor Overhauser DNP properties with nitroxides embedded into them. An increase of spectral line broadening, or lower tumbling rates of the larger carriers seem to be the reasons for the significant drop in ODNP performance. Cyclodextrines with nitroxides showed a reasonable enhancement with improved water solubility enabling the use of lipophilic radicals. A stability improvement of up to 30% in the presence of ascorbic acid was measured via ULF NMR spectroscopy. Some nitroxides with γ-cyclodextrin showed reduction in cell viability experiments as seen by PI staining and a decrease in metabolic activity as revealed by the MTT assay, however, these effects were ascribed mostly to the vehicle itself. Conclusions Even though most carrier systems decrease the ODNP efficiency, cyclodextrine-based radicals seem to be a promising candidate for future ultralow field Overhauser MRI in vivo experiments and high field T1 contrast agents. They show improved stability compared to nitroxides without carrier systems. Further investigations should show, if only lipophilic nitroxides benefit from being embedded into cyclodextrine. Acknowledgement This work was supported with ERA.Net RUS+ project ST2017-382: NanoHyperRadicals (including RFBR 18-53-76003-ERA-A). Disclosure I or one of my co-authors have no financial interest or relationship to disclose regarding the subject matter of this presentation