Alterations in Intracardiac Flow Patterns Affect Mitral Leaflets Dynamics in a Model of Ischemic Mitral Regurgitation.

PURPOSE: This study was to evaluate the effects of ischemic mitral regurgitation (IMR) on vortex formation and leaflet dynamics using an established porcine infarct model of IMR. METHODS: Using direct coronary ligation, five animals were subjected to a posterolateral myocardial infarction (MI) followed by an MRI at 12-weeks post MI. MR imaging consisted of 4D time-resolved left ventricular (LV) flow, full coverage 2D LV cine, and high resolution 2D cine of mitral valve dynamics. Five additional naïve animals underwent identical imaging protocols to serve as controls. Image analysis was performed to obtain mitral transvalvular flows as well as LV volumes throughout the cardiac cycle. In addition, anterior to posterior mid-leaflet tip distances were measured throughout the cardiac cycle for determination of temporal leaflet dynamics. RESULTS: It was found IMR caused asymmetric vortex ring formation with the anterior vortex having a lower vorticity relative to its posterior counterpart. In contrast, normal ventricles create symmetric and tightly curled vortices in the basal chamber just underneath the mitral leaflets which conserve kinetic energy and aid in effective ejection. IMR animals were also evaluated for leaflet separation and were found to have a greater leaflet opening and achieved peak vorticity and peak leaflet opening later than control animals. CONCLUSION: In conclusion, this study shows the effects that altered vortex formation, due to IMR, can have on ventricular filling and leaflet dynamics. These findings have important implications for understanding blood flow through the dilated heart and how ring annuloplasty and volume reduction interventions may influence mitral valve dynamics.

Qualitative Assessment and Reporting Quality of Intracranial Vessel Wall MR Imaging Studies: A Systematic Review.

BACKGROUND: Over the last quarter-century, the number of publications using vessel wall MR imaging has increased. Although many narrative reviews offer insight into technique and diagnostic applications, a systematic review of publication trends and reporting quality has not been conducted to identify unmet needs and future directions. PURPOSE: We aimed to identify which intracranial vasculopathies need more data and to highlight areas of strengths and weaknesses in reporting. DATA SOURCES: PubMed, EMBASE, and MEDLINE databases were searched up to September 2018 in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. DATA ANALYSIS: Two independent reviewers screened and extracted data from 128 articles. The Strengthening the Reporting of Observational Studies in Epidemiology guidelines were used to assess the reporting quality of analytic observational studies. DATA SYNTHESIS: There has been an exponentially increasing trend in the number of vessel wall MR imaging publications during the past 24 years (P < .0001). Intracranial atherosclerosis is the most commonly studied intracranial vasculopathy (49%), followed by dissections (13%), aneurysms (8%), and vasculitis (5%). Analytic observational study designs composed 48% of the studies. Transcontinental collaborations showed nonsignificantly higher reporting quality compared with work originating from single continents (P = .20). LIMITATIONS: A limitation is the heterogeneity in study designs. CONCLUSIONS: Investigations on the diagnostic utility of vessel wall MR imaging in less commonly studied intracranial vasculopathies such as dissections, aneurysms, and vasculitis are warranted. More consistent adherence to the Strengthening the Reporting of Observational Studies in Epidemiology guidelines should improve transparency and maximize effective synthesis for clinical translation. Diverse collaborative teams are encouraged to advance the understanding of intracranial vasculopathies using vessel wall MR imaging.

Sodium MR imaging detection of mild Alzheimer disease: preliminary study.

BACKGROUND AND PURPOSE: There is significant interest in the development of novel noninvasive techniques for the diagnosis of Alzheimer disease (AD) and tracking its progression. Because MR imaging has detected alterations in sodium levels that correlate with cell death in stroke, we hypothesized that there would be alterations of sodium levels in the brains of patients with AD, related to AD cell death. MATERIALS AND METHODS: A total of 10 volunteers (5 with mild AD and 5 healthy control subjects) were scanned with a 20-minute sodium (23Na) MR imaging protocol on a 3T clinical scanner. RESULTS: After normalizing the signal intensity from the medial temporal lobes corresponding to the hippocampus with the ventricular signal intensity, we were able to detect a 7.5% signal intensity increase in the brains of patients with AD (AD group, 68.25% +/- 3.4% vs control group, 60.75% +/- 2.9%; P < .01). This signal intensity enhancement inversely correlated with hippocampal volume (AD group, 3.22 +/- 0.50 cm3 vs control group, 3.91 +/- 0.45 cm3; r2 = 0.50). CONCLUSIONS: This finding suggests that sodium imaging may be a clinically useful tool to detect the neuropathologic changes associated with AD.