Purpose To compare arterial spin labeling (ASL) data between low- and high-grade brain tumors in children to establish a cutoff to distinguish low- from high-grade neoplasms and to assess potential correlations between cerebral blood flow (CBF) and quantitative histologic microvascular data. Materials and Methods Approval was obtained from the regional review board. ASL data obtained in 129 children between 2011 and 2015 were retrospectively analyzed. CBF and relative CBF in the most perfused area of each neoplasm and contrast enhancement were quantified with a semiquantitative ratio. The correlation between CBF and microvascular density was analyzed in specimens stained with anti-CD34. Results were controlled in two validation cohorts with 1.5- and 3.0-T magnetic resonance (MR) imaging. Results Mean CBF was significantly higher for high-grade than for low-grade hemispheric (116 mL/min/100 g [interquartile range {IQR}, 73-131 mL/min/100 g] vs 29 mL/min/100 g [IQR, 23-35 29 mL/min/100 g], P < .001), thalamic (87 mL/min/100 g [IQR, 73-100 mL/min/100 g] vs 36 mL/min/100 g [IQR, 30-40 mL/min/100 g], P = .016), and posterior fossa (59 mL/min/100 g [IQR, 45-91 mL/min/100 g] vs 33 mL/min/100 g [IQR, 25-40 mL/min/100 g], P < .001) tumors. With a cutoff of 50 mL/min/100 g, sensitivity and specificity were 90% (95% confidence interval [CI]: 68, 100) and 93% (95% CI: 66, 100), respectively, for hemispheric tumors; 100% (95% CI: 48, 100) and 80% (95% CI: 28, 100), respectively, for thalamic tumors; and 65% (95% CI: 51, 78) and 94% (95% CI: 80, 99), respectively, for posterior fossa tumors. In posterior fossa tumors, additional use of the CBF-to-contrast enhancement ratio yielded sensitivity and specificity of 96% (95% CI: 87, 100) and 97% (95% CI: 84, 100), respectively. Use of a simple algorithm based on these values yielded an accuracy of 93% (95% CI: 87, 97). Validation sets yielded similar results, with grading accuracy of 88% (95% CI: 62, 98) with 1.5-T MR imaging and 77% (95% CI: 46, 95) with 3.0-T MR imaging. CBF was strongly correlated with microvascular density (R = 0.66, P < .001). Conclusion High-grade pediatric brain tumors display higher CBF than do low-grade tumors, and they may be accurately graded by using these values. CBF is correlated with tumor microvascular density. RSNA, 2016 Online supplemental material is available for this article.

We found an association between daily asthma exacerbation in paediatric visits to the ED and fine particulate air pollutants.

According to the European AIDS Clinical Society, tenofovir disoproxil fumarate can be used in HIV-infected pregnant women if started prior to pregnancy, although no data are available on the pharmacokinetics of tenofovir (TFV) during pregnancy. The aim of this study was to describe TFV pharmacokinetics in HIV-infected women and to evaluate the effect of pregnancy on TFV disposition. Samples were collected according to a therapeutic drug monitoring in 186 women, including 46 pregnant women treated with TFV and retrospectively analyzed by a population approach. TFV pharmacokinetics were ascribed to an open two-compartment model with linear absorption and elimination. The mean population parameter estimates (between-subject variability) were as follows: absorption rate constant, 0.56 h ؊1 ; elimination clearance, 59.9 liters h ؊1 (0.436); central volume of distribution, 552 liters (1.96); intercompartmental clearance, 172 liters/h; and peripheral volume of distribution, 1,390 liters. Pregnant women had a 39% higher apparent clearance compared to nonpregnant women. Apparent clearance significantly decreased with age. In order to obtain an exposure similar to the known exposure in adults and guarantee similar trough concentrations (C min ) as observed in adults, an increase in the TFV dose should be considered for women from the second trimester to delivery. Because of the lack of data on the use of tenofovir disoproxil fumarate (TDF) in pregnancy and concerns over possible bone toxicity, U.S. guidelines recommend that TDF-based highly active antiretroviral therapy (HAART) should be used only after careful considerations of alternatives (8). However, for women who were already treated by TDF prior to pregnancy, European AIDS Clinical Society guidelines recommend to continue the TDF treatment during pregnancy. Thus, in these therapeutic drug monitoring data, some women were taking TDF during their pregnancy in the first, second, and third trimester.TDF is already taken during pregnancy at the same dose as in adults although physiological changes associated with pregnancy can lead to significant variations in pharmacokinetics (modified absorption, distribution, and elimination). No pharmacokinetic data on the use of TDF before the 38th week of pregnancy are available. Two studies restricted to late pregnancy and labor suggest that tenofovir (TFV) exposure is lower than nonpregnant adult exposure (9, 16).We performed here a population pharmacokinetic study of women during pregnancy, at delivery, and out of pregnancy in order to investigate TFV pharmacokinetics throughout pregnancy. MATERIALS AND METHODSPatients and treatments. The population included nonpregnant women, pregnant women, and women on the day of delivery receiving oral TFV for treatment of HIV infection and whose antiretroviral drug plasma concentrations were monitored on a routine basis. TFV was administered chronically using a 300-mg once-daily regimen. For each woman, the time elapsed between administration and sampling times, the time of dosing, the bod...