Quantitative assessment of velocity and flow using compressed SENSE in children and young adults with adequate acquired temporal resolution

Background Phase contrast (PC) cardiovascular magnetic resonance (CMR) imaging with parallel imaging acceleration is established and validated for measuring velocity and flow. However, additional acceleration to further shorten acquisition times would be beneficial in patients with complex vasculature who need multiple PC-CMR measurements, especially pediatric patients with higher heart rates. Methods PC-CMR images acquired with compressed sensitivity encoding (C-SENSE) factors of 3 to 6 and standard of care PC-CMR with sensitivity encoding (SENSE) factor of 2 (S2) acquired as part of clinical CMR examinations performed between November 2020 and January 2021 were analyzed retrospectively. The velocity and flow through the ascending aorta (AAo), descending aorta (DAo), and superior vena cava (SVC) in a transverse plane at the level of pulmonary artery bifurcation were compared. Additionally, frequency power distribution and dynamic time warp distance were calculated for these acquisitions. To further validate the adequate temporal resolution requirement, patients with S2 PC-CMR in the same acquisition plane were added in frequency power distribution analysis. Results Twenty-eight patients (25 males; 15.9 ± 1.9 years; body surface area (BSA) 1.7 ± 0.2 m2; heart rate 81 ± 16 bpm) underwent all five PC-CMR acquisitions during the study period. An additional 22 patients (16 males; 17.5 ± 7.7 years; BSA 1.6 ± 0.5 m2; heart rate 91 ± 16 bpm) were included for frequency power spectrum analysis. As expected, scan time decreased with increasing C-SENSE acceleration factor = 3 (37.5 ± 6.5 s, 26.4 ± 7.6%), 4 (28.1 ± 4.9 s, 44.7 ± 5.6%), 5 (21.6 ± 3.6 s, 57.6 ± 4.4%), and 6 (19.1 ± 3.2 s, 62.3 ± 4.2%) relative to SENSE = 2 (51.3 ± 10.1 s) PC-CMR acquisition. Mean peak velocity, net flow, and cardiac output were comparable (p > 0.87) between the five PC-CMR acquisitions with mean differences less than < 4%, < 2%, and < 3% respectively. All individual blood vessels showed a non-significant dependence of difference in fmax99 (< 4 Hz, p > 0.2), and dynamic time warp distance (p > 0.3) on the C-SENSE acceleration factor used. There was a strongly correlated (r = 0.74) increase in fmax99 (10.5 ± 2.2, range: 7.1–16.4 Hz) with increasing heart rate. The computed minimum required cardiac phase number was 15 ± 2.0 (range: 11–20) over the heart rate of 86 ± 15 bpm (range: 58–113 bpm). Conclusions Stroke volume, cardiac output, and mean peak velocity measurements using PC-CMR with C-SENSE of up to 6 agree with measurements by standard of care PC-CMR with SENSE = 2 and resulted in up to a 65% reduction in acquisition time. Adequate temporal sampling can be ensured by acquiring 20 cardiac phases throughout the entire cardiac cycle over a wide range of pediatric and young adult heart rates.

Let’s Do the Time Warp Again: Youth Interpreters at Fort Edmonton Park Performing Possibilities across Time

Dans cet article, Heather Fitzsimmons Frey et Tania Gigliotti cherchent à voir comment les prestations données par les jeunes dans un musée d’histoire vivante encouragent les gens à reconcevoir le passé de manière à y inscrire des futurs potentiels, une agence, des choix et des changements. Leur recherche est basée sur des entretiens effectués auprès de jeunes bénévoles travaillant à Fort Edmonton Park (Edmonton, Alberta) dans le cadre du projet Young People are the Future (2019-20). Ces bénévoles ont été appelés à explorer ce que signifie représenter l’avenir tel que le veulent les discours populaires tout en interprétant le passé colonial d’Edmonton en lien avec les Premières Nations. Fitzsimmons Frey et Gigliotti se servent de constructions culturelles historiques et contemporaines de « la jeunesse » et de « l’adolescence » (Alexander, Comacchio, Harris, Ishiguro, Lesko, van de Water), de cadres empruntés au domaine des études sur l’âge (Gullette, Henderson, Twigg, Woodward), de la théorie brechtienne (Diamond) et de notions liées à la nostalgie (Goulding, Heddon) pour examiner comment les spectacles de reconstitution et les musées d’histoire réussissent à créer un temps non linéaire et syncopé (Schneider). Les jeunes interprètes du parc ouvrent un espace de réflexion critique sur le choix intentionnel dans un lieu qui pourrait être perçu comme étant enraciné et fixe. Soutenus par une souplesse au niveau du style d’interprétation, leurs tenues historiques, le travail sur leur personnage, leurs rapports avec leurs collègues et le pouvoir d’injecter des histoires dans le récit historique qu’ils interprètent, les jeunes bénévoles montrent que le passé peut faire preuve d’autant de souplesse que le peut l’avenir.