Trends in Well-Child Visits and Routine Vaccination among Children of U.S. Military Members: An Evaluation of the COVID-19 Pandemic Effects.

The COVID-19 pandemic has drastically impacted administration of healthcare including well-child visits and routine vaccinations. The purpose of this study was to determine the impact of COVID-19 pandemic disruption on childhood health maintenance: well-child visits and scheduled vaccinations. We queried the TRICARE Management Activity's Military Health System (MHS) database for outpatient well-child visits and vaccinations for all children 0 to 23 months of age eligible for TRICARE healthcare. The median rate of well-child visits, during the COVID-19 period (March 2020-July 2021), was significantly declined for all demographic groups: all ages, parental military ranks, sex, and regions as compared to the pre-COVID-19 period (February 2019-February 2020). Similar to rates of well-child visits, the rate of vaccinations declined during the COVID-19 period as compared to the pre-COVID-19 period for all demographic groups, except children 12-23 months. Rates of well-child visits for military dependent children under 2 years of age were decreased during the 16 month COVID-19 period, with large increases seen in the first 2 months of the pandemic; the consequences of missed well-child visits and vaccination are unknown.

Stabilization of T2 relaxation and magnetization transfer in cartilage explants by immersion in perfluorocarbon liquid.

PURPOSE: Magnetic resonance imaging of ex vivo cartilage measures parameters such as T2 and magnetization transfer ratio (MTR), which reflect structural changes associated with osteoarthritis. Samples are often immersed in aqueous solutions to prevent dehydration and to to improve susceptibility matching. This study sought to determine the extent to which T2 and MTR changes are attributable to immersion alone and to identify immersion conditions to minimize this confounding factor. METHODS: T2 and MTR were measured before and after immersion for up to 24 hours at 4°C. Bovine nasal and articular cartilage and human articular cartilage were studied. Experimental groups included undisturbed immersion in Fluorinert FC-770, a susceptibility-matched, hydrophobic liquid with minimal tissue penetration, and immersion in Fluorinert, Dulbecco's phosphate-buffered saline (DPBS), or saline, with removal from the magnet between scans. 19 F and 1 H-MRI were used to detect cartilage penetration by Fluorinert and swelling, respectively. RESULTS: Saline and DPBS immersion rapidly increased T2 , wet weight and cartilage volume and decreased MTR, suggesting increased water content for all cartilage types. Fluorinert-immersed samples exhibited minimal changes in T2 or MTR. No ingress of Fluorinert was detected after 2 weeks of continuous immersion at 4°C. CONCLUSION: Ex vivo quantitative MR studies of cartilage may be confounded by the effects of immersion in aqueous solution, which may be comparable to or larger than effects attributed to pathology. These effects may be mitigated by immersion in perfluorocarbon liquids such as Fluorinert FC-770.

Clinical high-resolution mapping of the proteoglycan-bound water fraction in articular cartilage of the human knee joint.

PURPOSE: We applied our recently introduced Bayesian analytic method to achieve clinically-feasible in-vivo mapping of the proteoglycan water fraction (PgWF) of human knee cartilage with improved spatial resolution and stability as compared to existing methods. MATERIALS AND METHODS: Multicomponent driven equilibrium single-pulse observation of T1 and T2 (mcDESPOT) datasets were acquired from the knees of two healthy young subjects and one older subject with previous knee injury. Each dataset was processed using Bayesian Monte Carlo (BMC) analysis incorporating a two-component tissue model. We assessed the performance and reproducibility of BMC and of the conventional analysis of stochastic region contraction (SRC) in the estimation of PgWF. Stability of the BMC analysis of PgWF was tested by comparing independent high-resolution (HR) datasets from each of the two young subjects. RESULTS: Unlike SRC, the BMC-derived maps from the two HR datasets were essentially identical. Furthermore, SRC maps showed substantial random variation in estimated PgWF, and mean values that differed from those obtained using BMC. In addition, PgWF maps derived from conventional low-resolution (LR) datasets exhibited partial volume and magnetic susceptibility effects. These artifacts were absent in HR PgWF images. Finally, our analysis showed regional variation in PgWF estimates, and substantially higher values in the younger subjects as compared to the older subject. CONCLUSIONS: BMC-mcDESPOT permits HR in-vivo mapping of PgWF in human knee cartilage in a clinically-feasible acquisition time. HR mapping reduces the impact of partial volume and magnetic susceptibility artifacts compared to LR mapping. Finally, BMC-mcDESPOT demonstrated excellent reproducibility in the determination of PgWF.