Predicting the outcome of grade II glioma treated with temozolomide using proton magnetic resonance spectroscopy

International audienceBACKGROUND: This study was designed to evaluate proton magnetic resonance spectroscopy ((1)H-MRS) for monitoring the WHO grade II glioma (low-grade glioma (LGG)) treated with temozolomide (TMZ).METHODS: This prospective study included adult patients with progressive LGG that was confirmed by magnetic resonance imaging (MRI). Temozolomide was administered at every 28 days. Response to TMZ was evaluated by monthly MRI examinations that included MRI with volumetric calculations and (1)H-MRS for assessing Cho/Cr and Cho/NAA ratios. Univariate, multivariate and receiver-operating characteristic statistical analyses were performed on the results.RESULTS: A total of 21 LGGs from 31 patients were included in the study, and followed for at least n=14 months during treatment. A total of 18 (86%) patients experienced a decrease in tumour volume with a greater decrease of metabolic ratios. Subsequently, five (28%) of these tumours resumed growth despite the continuation of TMZ administration with an earlier increase of metabolic ratios of 2 months. Three (14%) patients did not show any volume or metabolic change. The evolutions of the metabolic ratios, mean(Cho/Cr)(n) and mean(Cho/NAA)(n), were significantly correlated over time (Spearman ρ=+0.95) and followed a logarithmic regression (P>0.001). The evolutions over time of metabolic ratios, mean(Cho/Cr)(n) and mean(Cho/NAA)(n), were significantly correlated with the evolution of the mean relative decrease of tumour volume, mean(ΔV(n)/V(o)), according to a linear regression (P<0.001) in the 'response/no relapse' patient group, and with the evolution of the mean tumour volume (meanV(n)), according to an exponential regression (P<0.001) in the 'response/relapse' patient group. The mean relative decrease of metabolic ratio, mean(Δ(Cho/Cr)(n)/(Cho/Cr)(o)), at n=3 months was predictive of tumour response over the 14 months of follow-up. The mean relative change between metabolic ratios, mean((Cho/NAA)(n)-(Cho/Cr)(n))/(Cho/NAA)(n), at n=4 months was predictive of tumour relapse with a significant cutoff of 0.046, a sensitivity of 60% and a specificity of 100% (P=0.004).CONCLUSIONS: The (1)H-MRS profile changes more widely and rapidly than tumour volume during the response and relapse phases, and represents an early predictive factor of outcome over 14 months of follow-up. Thus, (1)H-MRS may be a promising, non-invasive tool for predicting and monitoring the clinical response to TMZ

Forecasting Daily Variability of the S and P 100 Stock Index using Historical, Realised and Implied Volatility Measurements

The increasing availability of financial market data at intraday frequencies has not only led to the development of improved volatility measurements but has also inspired research into their potential value as an information source for volatility forecasting. In this paper we explore the forecasting value of historical volatility (extracted from daily return series), of implied volatility (extracted from option pricing data) and of realised volatility (computed as the sum of squared high frequency returns within a day). First we consider unobserved components and long memory models for realised volatility which is regarded as an accurate estimator of volatility. The predictive abilities of realised volatility models are compared with those of stochastic volatility models and generalised autoregressive conditional heteroskedasticity models for daily return series. These historical volatility models are extended to include realised and implied volatility measures as explanatory variables for volatility. The main focus is on forecasting the daily variability of the Standard and Poor's 100 stock index series for which trading data (tick by tick) of almost seven years is analysed. The forecast assessment is based on the hypothesis of whether a forecast model is outperformed by alternative models. In particular, we will use superior predictive ability tests to investigate the relative forecast performances of some models. Since volatilities are not observed, realised volatility is taken as a proxy for actual volatility and is used for computing the forecast error. A stationary bootstrap procedure is required for computing the test statistic and its $p$-value. The empirical results show convincingly that realised volatility models produce far more accurate volatility forecasts compared to models based on daily returns. Long memory models seem to provide the most accurate forecasts

Population, resources, and environment: Implications of human behavioral ecology for conservation

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43481/1/11111_2005_Article_BF02207996.pd

Phacoemulsification outcomes and complications in vitrectomised versus non-vitrectomised eyes

Clinical relevance: Pars plana vitrectomy techniques have evolved in the recent years and the number of patients undergoing phacoemulsification for post-vitrectomy cataract has increased. Eye-care practitioners need to be aware of intraoperative complications and post-operative outcomes in previously vitrectomised eyes. Background: The aim of the present study is to compare the outcomes and related complications of phacoemulsification in previously vitrectomised versus non-vitrectomised eyes. Methods: This is a retrospective case-control study. Visual acuity, refractive outcomes, intra- and post-operative complications were analysed in consecutive phacoemulsification patients between January 2015 and August 2017. Patients with no post-operative data were excluded. Results: One hundred and forty-nine previously vitrectomised eyes and 608 non-vitrectomised eyes were included in the analysis. Previous pars plana vitrectomy was associated with worse logMAR visual acuity pre-operatively (0.75 ± 0.54 vs. 0.40 ± 0.33, p < 0.0001) and post-operatively (0.15 ± 0.29 vs. 0.09 ± 0.22, p = 0.014). There were no statistically significant differences between the two groups regarding refractive outcomes (p = 0.393) or posterior capsule rupture rate (p = 0.223). Previous pars plana vitrectomy was associated with a higher risk of post-operative macular oedema (p = 0.046) and posterior capsule opacification (p < 0.0001). Conclusions: Previous pars plana vitrectomy was not associated with a higher risk of intraoperative complications. However, a higher incidence of cystoid macular oedema and posterior capsule opacification were identified in the present study. Further research can provide insight into the mechanisms involved and any appropriate prevention strategies for these conditions. © 2021 Optometry Australia

Visual acuity outcomes after phacoemulsification in eyes with good visual acuity before cataract surgery

Objective: to analyse cataract surgery outcomes and related factors in eyes presenting with good visual acuity. Subject and Methods: A retrospective longitudinal study of patients undergoing phacoemulsification between 2014 and 2018 in Moorfields Eye Hospital was conducted. Pre- and post-operative visual acuities were analysed. Inclusion criteria were age ≥40 years and pinhole visual acuity ≥6/9 pre-operatively. Exclusion criteria were no post-operative visual acuity data. The visual acuity change variable was also defined according to post-operative visual acuity being above or below the Snellen 6/9 threshold. Results: 2,720 eyes were included. The unaided logMAR visual acuity improved from 0.54 to 0.20 (p < 0.001), the logMAR visual acuity with glasses improved from 0.35 to 0.05 (p < 0.001), and the logMAR pinhole visual acuity improved from 0.17 to 0.13 (p < 0.001); 8.1% of patients had Snellen visual acuity <6/9 post-operatively. Mean follow-up period was 23.6 ± 9.9 days. In multivariate analysis, factors associated with visual acuity <6/9 post-operatively were age (OR = 0.96, 95% confidence interval [CI] [0.95, 0.98], p < 0.001), vitreous loss (OR = 0.21, 95% CI [0.08, 0.56], p = 0.002), and iris trauma (OR = 0.28, 95% CI [0.10, 0.82] p = 0.02). Conclusions: Visual acuity improved significantly, although at least 8.1% of them did not reach their pinhole preoperative visual acuity. Worse visual acuity outcomes were associated with increasing age, vitreous loss, and iris trauma. The 6/9 vision threshold may not be able to accurately differentiate those who may benefit from cataract surgery and those who may not. © 2021 The Author(s). Published by S. Karger AG, Basel