Accuracy of ultrasonography in the assessment of liver fat compared with MRI.

AIM: To investigate the accuracy of ultrasonography in the assessment of hepatic steatosis using magnetic resonance imaging (MRI) as standard of reference and to explore the influence of additional hepatic iron overload. MATERIAL AND METHODS: A total of 2,783 volunteers (1,442 women, 1,341 men; mean age, 52.3±13.8 years) underwent confounder-corrected chemical-shift-encoded MRI of the liver at 1.5 T. Proton-density fat fraction (PDFF) and transverse relaxation rate (R2*) were calculated to estimate hepatic steatosis and liver iron overload, respectively. In addition, the presence of hepatic steatosis was assessed by B-mode ultrasonography. The sensitivity, specificity, and accuracy of hepatic ultrasonography were determined for different degrees of hepatic steatosis and different amounts of liver iron. RESULTS: MRI revealed hepatic steatosis in 40% of participants (n=1,112), which was mild in 68.9% (n=766), moderate in 26.7% (n=297), and severe in 4.4% (n=49) of patients. Ultrasonography detected hepatic steatosis in 37.8% (n=1,052), corresponding to 74.5% sensitivity and 86.6% specificity. The sensitivity of ultrasound increased with the amount of hepatic fat present and was 65.1%, 95%, and 96% for low, moderate, and high fat content; whereas the specificity was constantly high at 86.6%. The diagnostic accuracy of ultrasound for detection of hepatic steatosis did not vary significantly with the amount of liver iron present. CONCLUSION: Ultrasonography is an excellent tool to assess hepatic steatosis in the clinical setting with some limitations in patients with a low liver fat content. The detection of hepatic steatosis by ultrasonography is not influenced by liver iron.

[Current value of quinolones in Helicobacter pylori therapy]. / Aktueller Stellenwert von Fluorchinolonen in der Helicobacter-pylori-Therapie.

Eradication rates in first-line Helicobacter pylori therapy have been declining over the last decades, mainly due to increasing resistance against the recommended antibiotics clarithromycin and metronidazole. Thus, there is a need to evaluate novel regimens and substances to offer effective alternative treatment strategies. New generation quinolones, like levofloxacin and moxifloxacin, exhibit a broad-spectrum activity against various Gram-positive and Gram-negative strains and are mostly well tolerated. Based on a large number of studies, quinolones have been introduced in second-line and rescue treatment and are recommended for these indications in current guidelines. Various studies have investigated alternative strategies for first-line treatment including quinolone-based regimens. In the context of increasing resistance rates of Helicobacter pylori against quinolones some risks and benefits have to be considered when using quinolones as a first-line strategy. Besides numerous studies investigating levofloxacin and moxifloxacin there are some promising results for the new substance sitafloxacin, which might overcome primary resistance of Helicobacter pylori against conventional quinolones.

Bifurcations and transport barriers in the resistive-g paradigm

The so-called resistive-g (resistive pressure-gradient-driven turbulence) paradigm is a widely accepted and frequently investigated model for nonlinear plasma dynamics. The parameter dependences of the generated transport barriers as well as third order bifurcations will be discussed numerically and analytically in the present paper. First, using a Galerkin representation, bifurcating states (from the conductive states in a rectangular cell) are investigated for the cases when only one unstable mode dominates. The dependence of the bifurcation properties on the aspect ratio of the domain is discussed, leading to the conclusion that for vanishing (or small) magnetic shear the so-called low, high, and edge localized mode transitions do not occur for small aspect ratios of the domain. Including reasonable magnetic shear, the small-aspect-ratio cutoff disappears, and transport barriers may exist in a broad parameter range. Second, for small aspect ratios, interesting codimension-2 bifurcations occur. When unfolding the dynamics up to third order, e.g., a weakly nonlinear interaction of convection cells is observed. The analytical results are confirmed by numerical simulations.