Keisuke Osakabe

PURPOSE: Shear wave velocity (Vs) measurements can be unstable in individuals with obesity or with a skin-capsule distance (SCD) of ≥ 20 mm. However, instability of Vs has also been observed in cases where SCD is not markedly increased; therefore, the present study aimed to investigate the factors contributing to reduced VsN (net amount of effective shear wave velocity), an index that reflects the reliability of individual Vs measurements. METHODS: In total, 317 individuals who underwent community-based health screening were included in this study. We investigated the relationship between VsN and physical findings, laboratory data, SCD, and structure of the SCD (single vs. multilayered) to identify factors associated with decreased VsN. RESULTS: Multiple regression analysis revealed that body fat percentage (β = - 0.135, p = 0.011), SCD (β = - 0.347, p < 0.0001), and the structure of the SC region (β = - 0.295, p < 0.0001) were independently associated with decreased VsN. In cases where the SCD exceeded 20 mm, the VsN within the SCD was significantly lower in the multilayer structural type [52 (28-75)] than in the single-layer structural type [95 (77-99)] (p = 0.004). Furthermore, even when the SCD was 20 mm or less, the VsN within the SCD was significantly lower in the multilayer structure type [80 (68-89)] than in the single-layer structure type [99 (92-100)] (p < 0.0001). CONCLUSION: The results show that, in addition to SCD thickness, its internal structure reduces the VsN and contributes to Vs measurement instability.

OBJECTIVE: The accuracy of self-reported seizure-freedom duration are essentially limited. Scalp high-frequency oscillations (HFOs) are more tightly linked to seizures than spikes alone and are a promising new biomarker. The purpose of this study is to determine the relationship between scalp HFO and time since the last reported seizure. METHODS: The study population consisted of 169 pediatric epilepsy patients (91 males; age range, 0-20 years). A holdout method was used to develop and validate a predictive model (multivariate HFO model) to estimate the time since the last reported seizure. RESULTS: The multivariate HFO model was created with four variables: scalp HFO detection rate, developmental delay, epilepsy duration, and the use of antiepileptic drugs. The area under the curve (AUC) of the multivariate HFO model was higher than that for the HFO and spike models in all four discriminations for time since the last reported seizure (≥ 2 years: AUC = 0.95, ≥ 1 year: 0.91, ≥ 2 months: 0.82, and ≥ 2 weeks: 0.76). CONCLUSIONS: The multivariate HFO model showed higher performance in patients with a longer time since the last reported seizure (≥ 1 year). SIGNIFICANCE: This model may help establish a new measure of epilepsy remission.