Impact of sex on the management and outcome of aortic stenosis patients.

OBJECTIVE: The aim of this study was to assess the impact of sex on the management and outcome of patients according to aortic stenosis (AS) severity. INTRODUCTION: Sex differences in the management and outcome of AS are poorly understood. METHODS: Doppler echocardiography data of patients with at least mild-to-moderate AS [aortic valve area (AVA) ≤1.5 cm2 and peak jet velocity (VPeak) ≥2.5 m/s or mean gradient (MG) ≥25 mmHg] were prospectively collected between 2005 and 2015 and retrospectively analysed. Patients with reduced left ventricular ejection fraction (<50%), or mitral or aortic regurgitation >mild were excluded. RESULTS: Among 3632 patients, 42% were women. The mean indexed AVA (0.48 ± 0.17 cm2/m2), VPeak (3.74 ± 0.88 m/s), and MG (35.1 ± 18.2 mmHg) did not differ between sexes (all P ≥ 0.18). Women were older (72.9 ± 13.0 vs. 70.1 ± 11.8 years) and had more hypertension (75% vs. 70%; P = 0.0005) and less coronary artery disease (38% vs. 55%, P < 0.0001) compared to men. After inverse-propensity weighting (IPW), female sex was associated with higher mortality (IPW-HR: 1.91 [1.14-3.22]; P = 0.01) and less referral to valve intervention (competitive model IPW-HR: 0.88 [0.82-0.96]; P = 0.007) in the whole cohort. This excess mortality in women was blunted in concordant non-severe AS initially treated conservatively (IPW-HR = 1.03 [0.63-1.68]; P = 0.88) or in concordant severe AS initially treated by valve intervention (IPW-HR = 1.25 [0.71-2.21]; P = 0.43). Interestingly, the excess mortality in women was observed in discordant low-gradient AS patients (IPW-HR = 2.17 [1.19-3.95]; P = 0.01) where women were less referred to valve intervention (IPW-Sub-HR: 0.83 [0.73-0.95]; P = 0.009). CONCLUSION: In this large series of patients, despite similar baseline hemodynamic AS severity, women were less referred to AVR and had higher mortality. This seemed mostly to occur in the patient subset with discordant markers of AS severity (i.e. low-gradient AS) where women were less referred to AVR.

Multivariate consistency of resting-state fMRI connectivity maps acquired on a single individual over 2.5 years, 13 sites and 3 vendors.

Studies using resting-state functional magnetic resonance imaging (rsfMRI) are increasingly collecting data at multiple sites in order to speed up recruitment or increase sample size. The main objective of this study was to assess the long-term consistency of rsfMRI connectivity maps derived at multiple sites and vendors using the Canadian Dementia Imaging Protocol (CDIP, www.cdip-pcid.ca). Nine to 10 min of functional BOLD images were acquired from an adult cognitively healthy volunteer scanned repeatedly at 13 Canadian sites on three scanner makes (General Electric, Philips and Siemens) over the course of 2.5 years. The consistency (spatial Pearson's correlation) of rsfMRI connectivity maps for seven canonical networks ranged from 0.3 to 0.8, with a negligible effect of time, but significant site and vendor effects. We noted systematic differences in data quality (i.e. head motion, number of useable time frames, temporal signal-to-noise ratio) across vendors, which may also confound some of these results, and could not be disentangled in this sample. We also pooled the long-term longitudinal data with a single-site, short-term (1 month) data sample acquired on 26 subjects (10 scans per subject), called HNU1. Using randomly selected pairs of scans from each subject, we quantified the ability of a data-driven unsupervised cluster analysis to match two scans of the same subjects. In this "fingerprinting" experiment, we found that scans from the Canadian subject (Csub) could be matched with high accuracy intra-site (>95% for some networks), but that the accuracy decreased substantially for scans drawn from different sites and vendors, even falling outside of the range of accuracies observed in HNU1. Overall, our results demonstrate good multivariate stability of rsfMRI measures over several years, but substantial impact of scanning site and vendors. How detrimental these effects are will depend on the application, yet our results demonstrate that new methods for harmonizing multisite analysis represent an important area for future work.

The Canadian Dementia Imaging Protocol: Harmonizing National Cohorts.

BACKGROUND: Harmonized protocols to collect imaging data must be devised, employed, and maintained in multicentric studies to reduce interscanner variability in subsequent analyses. PURPOSE: To present a standardized protocol for multicentric research on dementia linked to neurodegeneration in aging, harmonized on all three major vendor platforms. The protocol includes a common procedure for qualification, quality control, and quality assurance and feasibility in large-scale studies. STUDY TYPE: Prospective. SUBJECTS: The study involved a geometric phantom, a single individual volunteer, and 143 cognitively healthy, mild cognitively impaired, and Alzheimer's disease participants in a large-scale, multicentric study. FIELD STRENGTH/SEQUENCES: MRI was perform with 3T scanners (GE, Philips, Siemens) and included 3D T1 w, PD/T2 w, T2* , T2 w-FLAIR, diffusion, and BOLD resting state acquisitions. ASSESSMENT: Measures included signal- and contrast-to-noise ratios (SNR and CNR, respectively), total brain volumes, and total scan time. STATISTICAL TESTS: SNR, CNR, and scan time were compared between scanner vendors using analysis of variance (ANOVA) and Tukey tests, while brain volumes were tested using linear mixed models. RESULTS: Geometric phantom T1 w SNR was significantly (P < 0.001) higher in Philips (mean: 71.4) than Siemens (29.5), while no significant difference was observed between vendors for T2 w (32.0 and 37.2, respectively, P = 0.243). Single individual volunteer T1 w CNR was higher in subcortical regions for Siemens (P < 0.001), while Philips had higher cortical CNR (P = 0.044). No significant difference in brain volumes was observed between vendors (P = 0.310/0.582/0.055). The average scan time was 41.0 minutes (SD: 2.8) and was not significantly different between sites (P = 0.071) and cognitive groups (P = 0.853). DATA CONCLUSION: The harmonized Canadian Dementia Imaging Protocol suits the needs of studies that need to ensure quality MRI data acquisition for the measurement of brain changes across adulthood, due to aging, neurodegeneration, and other etiologies. A detailed description, exam cards, and operators' manual are freely available at the following site: www.cdip-pcid.ca. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:456-465.

A dataset of long-term consistency values of resting-state fMRI connectivity maps in a single individual derived at multiple sites and vendors using the Canadian Dementia Imaging Protocol.

The impact of multisite acquisition on resting-state functional MRI (rsfMRI) connectivity has recently gained attention. We provide consistency values (Pearson's correlation) between rsfMRI connectivity maps of an adult volunteer (Csub) scanned 25 times over 3.5 years at 13 sites using the Canadian Dementia Imaging Protocol (CDIP, www.cdip-pcid.ca). This dataset was generated as part of the following article: Multivariate consistency of resting-state fMRI connectivity maps acquired on a single individual over 2.5 years, 13 sites and 3 vendors [1]. Acquired on three 3T scanner vendors (GE, Siemens and Philips), the Csub dataset is part of an ongoing effort to monitor the quality and comparability of MRI data collected across the Canadian Consortium on Neurodegeneration in Aging (CCNA) imaging network. The participant was scanned 25 times in the above-mentioned article: multiple times at six sites over a period of 2.5 years, and once at the remaining seven sites. Since then the participant was scanned an additional 45 times, allowing us to extend the dataset to 70 rsfMRI scans over a period of >4 years. In addition, we provide intra- and inter-subject consistency values of rsfMRI connectivity maps derived from 26 adult participants belonging to the publicly released Hangzhou Normal University dataset (HNU1). All HNU1 participants underwent 10 rsfMRI scans over one month on a single 3T scanner (GE). Connectivity maps of seven canonical networks were generated for each scan in the two datasets (Csub and HNU1). All consistency values, along with the scripts used to preprocess the rsfMRI data and generate connectivity maps and pairwise consistency values, have been made available on two public repositories, Github and Zenodo. We have also made available four Jupyter notebooks that use the provided consistency values to (a) generate interactive graphical summaries - 1 notebook, (b) perform statistical analyses - 2 notebooks, and (c) perform data-driven cluster analysis for the recovery of subject identity (i.e. rsfMRI fingerprinting) - 1 notebook. In addition, we provide two interactive dashboards that allow visualization of individual connectivity maps from the two datasets. Finally, we also provide minimally preprocessed rsfMRI data in Brain Imaging Data Standard (BIDS) format on all 70 scans in the extended dataset.

Structural and functional multi-platform MRI series of a single human volunteer over more than fifteen years.

We present MRI data from a single human volunteer consisting in over 599 multi-contrast MR images (T1-weighted, T2-weighted, proton density, fluid-attenuated inversion recovery, T2* gradient-echo, diffusion, susceptibility-weighted, arterial-spin labelled, and resting state BOLD functional connectivity imaging) acquired in over 73 sessions on 36 different scanners (13 models, three manufacturers) over the course of 15+ years (cf. Data records). Data included planned data collection acquired within the Consortium pour l'identification précoce de la maladie Alzheimer - Québec (CIMA-Q) and Canadian Consortium on Neurodegeneration in Aging (CCNA) studies, as well as opportunistic data collection from various protocols. These multiple within- and between-centre scans over a substantial time course of a single, cognitively healthy volunteer can be useful to answer a number of methodological questions of interest to the community.

Measurement Variability Following MRI System Upgrade.

Major hardware/software changes to MRI platforms, either planned or unplanned, will almost invariably occur in longitudinal studies. Our objective was to assess the resulting variability on relevant imaging measurements in such context, specifically for three Siemens Healthcare Magnetom Trio upgrades to the Prismafit platform. We report data acquired on three healthy volunteers scanned before and after three different platform upgrades. We assessed differences in image signal [contrast-to-noise ratio (CNR)] on T1-weighted images (T1w) and fluid-attenuated inversion recovery images (FLAIR); brain morphometry on T1w image; and small vessel disease (white matter hyperintensities; WMH) on FLAIR image. Prismafit upgrade resulted in higher (30%) and more variable neocortical CNR and larger brain volume and thickness mainly in frontal areas. A significant relationship was observed between neocortical CNR and neocortical volume. For FLAIR images, no significant CNR difference was observed, but WMH volumes were significantly smaller (-68%) after Prismafit upgrade, when compared to results on the Magnetom Trio. Together, these results indicate that Prismafit upgrade significantly influenced image signal, brain morphometry measures and small vessel diseases measures and that these effects need to be taken into account when analyzing results from any longitudinal study undergoing similar changes.

The Canadian Dementia Imaging Protocol: Harmonization validity for morphometry measurements.

The harmonized Canadian Dementia Imaging Protocol (CDIP) has been developed to suit the needs of a number of co-occurring Canadian studies collecting data on brain changes across adulthood and neurodegeneration. In this study, we verify the impact of CDIP parameters compliance on total brain volume variance using 86 scans of the same individual acquired on various scanners. Data included planned data collection acquired within the Consortium pour l'identification précoce de la maladie Alzheimer - Québec (CIMA-Q) and Canadian Consortium on Neurodegeneration in Aging (CCNA) studies, as well as opportunistic data collection from various protocols. For images acquired from Philips scanners, lower variance in brain volumes were observed when the stated CDIP resolution was set. For images acquired from GE scanners, lower variance in brain volumes were noticed when TE/TR values were within 5% of the CDIP protocol, compared to values farther from that criteria. Together, these results suggest that a harmonized protocol like the CDIP may help to reduce neuromorphometric measurement variability in multi-centric studies.

Magnetic resonance imaging (MRI) and prognostication in neonatal hypoxic-ischemic injury: a vignette-based study of Canadian specialty physicians.

Magnetic resonance imaging (MRI) could improve prognostication in neonatal brain injury; however, factors beyond technical or scientific refinement may impact its use and interpretation. We surveyed Canadian neonatologists and pediatric neurologists using general and vignette-based questions about the use of MRI for prognostication in neonates with hypoxic-ischemic injury. There was inter- and intra-vignette variability in prognosis and in ratings about the usefulness of MRI. Severity of predicted outcome correlated with certainty about the outcome. A majority of physicians endorsed using MRI results in discussing prognosis with families, and most suggested that MRI results contribute to end-of-life decisions. Participating neonatologists, when compared to participating pediatric neurologists, had significantly less confidence in the interpretation of MRI by colleagues in neurology and radiology. Further investigation is needed to understand the complexity of MRI and of its application. Potential gaps relative to our understanding of the ethical importance of these findings should be addressed.

Responding to requests of families for unproven interventions in neurodevelopmental disorders: hyperbaric oxygen "treatment" and stem cell "therapy" in cerebral palsy.

Faced with the limitations of currently available mainstream medical treatments and interventions, parents of children with neurodevelopmental disorders often seek information about unproven interventions. These interventions frequently have undetermined efficacy and uncertain safety profiles. In this article, we present a general background and case vignettes that highlight the use of hyperbaric oxygen chambers and stem cells in cerebral palsy, the leading cause of pediatric physical disability. We then review the current evidence about these interventions as exemplars of unproven therapies. Building on the background and cases, we explore and review two important questions related to unproven interventions: (1) How should clinicians respond to requests for innovative and alternative interventions? (2) What should clinicians keep in mind when such requests come from online sources?

Informed consent for videoconsultations in Canada.

We performed a qualitative study of the practice of informed consent for videoconsultation in Canada. Fourteen cases were examined: the 13 provinces and territories, and the Federal jurisdiction representing aboriginal groups. Twenty-seven interviews were conducted with key informants (14 telehealth experts, 13 legal experts). The telehealth experts were people with direct experience of telehealth practice. The majority of the telehealth experts agreed that videoconsultations had not been integrated into the health-care system. An interesting finding of the study was that the integration status of videoconsultations was not indicative of informed consent practices. Telehealth providers favoured express written consent, or risk management practices, although there was a desire to move towards implied consent models for videoconsultations. The study also showed that the legal ramifications of the electronic transmission of non-recorded, real-time, personal health information had not been explored. This represents an important factor in guiding future consent for videoconsultations in Canada.