Longitudinal changes in global structural brain connectivity and cognitive performance in former hospitalized COVID-19 survivors: an exploratory study.

BACKGROUND: Long-term sequelae of COVID-19 can result in reduced functionality of the central nervous system and substandard quality of life. Gaining insight into the recovery trajectory of admitted COVID-19 patients on their cognitive performance and global structural brain connectivity may allow a better understanding of the diseases' relevance. OBJECTIVES: To assess whole-brain structural connectivity in former non-intensive-care unit (ICU)- and ICU-admitted COVID-19 survivors over 2 months following hospital discharge and correlate structural connectivity measures to cognitive performance. METHODS: Participants underwent Magnetic Resonance Imaging brain scans and a cognitive test battery after hospital discharge to evaluate structural connectivity and cognitive performance. Multilevel models were constructed for each graph measure and cognitive test, assessing the groups' influence, time since discharge, and interactions. Linear regression models estimated whether the graph measurements affected cognitive measures and whether they differed between ICU and non-ICU patients. RESULTS: Six former ICU and six non-ICU patients completed the study. Across the various graph measures, the characteristic path length decreased over time (ß = 0.97, p = 0.006). We detected no group-level effects (ß = 1.07, p = 0.442) nor interaction effects (ß = 1.02, p = 0.220). Cognitive performance improved for both non-ICU and ICU COVID-19 survivors on four out of seven cognitive tests 2 months later (p < 0.05). CONCLUSION: Adverse effects of COVID-19 on brain functioning and structure abate over time. These results should be supported by future research including larger sample sizes, matched control groups of healthy non-infected individuals, and more extended follow-up periods.

Functional Foreign Accent Syndrome in suspected Conversion Disorder: A case study

Background and objectives: We provide a case analysis for a 28-year-old, native Dutch-speaking lady who developed Foreign Accent Syndrome (FAS), a few weeks after falling down the staircase. In addition to FAS, which gave the impression she spoke with a German accent, German(-like) words and structures occurred. Speech symptoms were aggravated by increased stress, fatigue or emotional pressure, and this triggered jargon speech. It was hypothesized her FAS and jargon developed on a functional basis.MethodsIn-depth analyses of the patient’s medical background, neuropsychological and neurolinguistic tests and psychodiagnostic exams were done. The patient participated in an fMRI experiment. In a syllable repetition paradigm, motor speech activations were compared to those of healthy individuals, to see whether they were altered, which would be expected in case of a neurological etiology.ResultsMedical history disclosed prior traumatic experiences for which she sought help, but no neurological incidents. Repeated neuropsychological and neurolinguistic tests showed deficits in recent memory and executive functioning. The patient demonstrated great difficulties with picture naming. Clinically, language switching and mixing as well as recurring jargon speech was found. Formal psychodiagnostic tests did not identify a clear disorder, but psychodiagnostic interviews were consistent with a DSM-5 conversion disorder. The fMRI study demonstrated that speech network activations corresponded to those found in healthy participants.ConclusionThe clinical neurolinguistic characteristics, outcome of the fMRI experiment, together with the clinical psychodiagnostic findings were strongly indicative for an underlying functional etiology for the FAS and jargon speech, presenting as symptoms of conversion disorder. (AU)

Synthetic MRI of Preterm Infants at Term-Equivalent Age: Evaluation of Diagnostic Image Quality and Automated Brain Volume Segmentation.

BACKGROUND AND PURPOSE: Neonatal MR imaging brain volume measurements can be used as biomarkers for long-term neurodevelopmental outcome, but quantitative volumetric MR imaging data are not usually available during routine radiologic evaluation. In the current study, the feasibility of automated quantitative brain volumetry and image reconstruction via synthetic MR imaging in very preterm infants was investigated. MATERIALS AND METHODS: Conventional and synthetic T1WIs and T2WIs from 111 very preterm infants were acquired at term-equivalent age. Overall image quality and artifacts of the conventional and synthetic images were rated on a 4-point scale. Legibility of anatomic structures and lesion conspicuity were assessed on a binary scale. Synthetic MR volumetry was compared with that generated via MANTiS, which is a neonatal tissue segmentation toolbox based on T2WI. RESULTS: Image quality was good or excellent for most conventional and synthetic images. The 2 methods did not differ significantly regarding image quality or diagnostic performance for focal and cystic WM lesions. Dice similarity coefficients had excellent overlap for intracranial volume (97.3%) and brain parenchymal volume (94.3%), and moderate overlap for CSF (75.6%). Bland-Altman plots demonstrated a small systematic bias in all cases (1.7%-5.9%) CONCLUSIONS: Synthetic T1WI and T2WI sequences may complement or replace conventional images in neonatal imaging, and robust synthetic volumetric results are accessible from a clinical workstation in less than 1 minute. Via the above-described methods, volume assessments could be routinely used in daily clinical practice.

Effects of AMI-25 on liver vessels and tumors on T1-weighted turbo-field-echo images: implications for tumor characterization.

This study was devoted to tumor differentiation in liver MR T1-weighted imaging with superparamagnetic iron oxide (SPIO). Twenty-one patients with 40 liver lesions were studied at 1.5 T. Before and at least 45 minutes after SPIO administration, turbo-field-echo (TFE) T1-weighted, TFE T1 x T2*-weighted (MXT), and fat-suppressed turbo-spin-echo T2-weighted images were acquired. A quantitative analysis was performed blindly. On TFE T1-weighted images, the signal enhancement was -33% +/- 12 for the liver, -24% +/- 2 for adenomas and focal nodular hyperplasia, +60% +/- 33 for the hemangiomas; metastases and cyst enhancement were not significant. After SPIO on TFE T1-weighted images, the hemangioma-to-liver signal ratio (149% +/- 18) was definitely higher than the mean metastasis-to-liver signal ratio (90% +/- 16). This T1-related differentiation ability lacked dramatically on TFE MXT images and, in one case, was reduced on post-SPIO TFE T1-weighted images by a long imaging delay after SPIO administration (2 hours).

Optimization schemes for selective excitations: application to the DIGGER pulses.

In this work, two distinct approaches to the tailoring of selective radiofrequency (RF) pulses were applied to a cos-sinc pulse of the DIGGER sequence used in localized spectroscopy. Ideally, three such pulses combined with a gradient in each direction destroy the Mz component of the magnetization everywhere but in the volume of interest. In the first approach, the optimal RF amplitude modulation is found by minimizing the difference between the ideal and the computed Mz profiles. In the second strategy, the RF pulse envelope is adjusted by optimization of the tip angle profile. Computed slice profiles optimized by each of these methods have been compared to experimental results. Simulations as well as experiments show that the second approach, which optimizes tip angles, is the most efficient.

The relationship between serum water proton T1 and protein content in the P388 leukemic mouse and the effect of chemotherapy by cis-diamminedichloroplatinum(II).

Proton NMR longitudinal relaxation times (T1; 10.7 MHz; 37 degrees C) were measured in the kidneys and blood serum of mice inoculated with P388 leukemia, and/or treated with the chemotherapeutic drug cis-diamminedichloroplatinum(II) (cis-Pt). In parallel, serum total protein content, urea and creatinine levels were determined and protein fractions were separated electrophoretically. Serum T1 was found to be 1518 +/- 73 ms (1 SD) in control mice, 1670 +/- 69 ms in leukemic mice, and 1380 +/- 71 ms in the healthy and the leukemic cis-Pt treated mice. The T1 increase in leukemic serum and T1 decrease in the serum of cis-Pt injected mice are attributed to decreased and increased protein contents respectively. A detailed analysis in terms of electrophoretic fractions of serum proteins reveals that the serum relaxation rate 1/T1 is a multilinear function of the mass concentrations of the main serum protein fractions, explaining all serum T1 effects. This makes T1 a non-specific blood parameter. The kidney T1 was found to be 311 +/- 12 ms in normal mice and 334 +/- 20 ms in leukemic mice. A dramatic T1 increase is observed when the mice are injected with cis-Pt; the values are 400 +/- 38 ms and 407 +/- 39 ms for healthy and leukemic mice, respectively. This effect is related to the nephrotoxicity of the drug, as evidenced by serum urea and creatinine levels and protein content being higher than normal.

Determinants of water proton T1 in blood serum.

Water proton T1 (10.7 MHz; 7 degrees C) and albumin and globulin contents were measured in the blood serum of 30 normal volunteers. The T1 relaxivity of serum albumin and globulin (i.e., the change of water relaxation rate 1/T1 per concentration unit) was determined in pure albumin and globulin solutions. It is shown that more than 90% of the serum relaxation rate 1/T1 is due to the proteins, making T1 a nonspecific blood parameter. In addition five pathological serum samples were examined, explaining clearly why serum T1 is not a clinically useful measurement.