Gadobenate dimeglumine-enhanced liver magnetic resonance imaging: value of hepatobiliary phase for the detection of focal liver lesions.

OBJECTIVE: The objective of the study was to determine the value of addition of hepatobiliary phase to dynamic gadobenate dimeglumine (Gd-BOPTA)-enhanced imaging for the detection of focal liver lesions (nodules with diameter ≤3.0 cm). METHODS: Routine nonenhanced magnetic resonance images were obtained in 25 patients with focal liver lesions suggested by ultrasonography and/or computed tomography.T1-weighted dynamic gradient-echo images were acquired immediately and 100 minutes after bolus injection of Gd-BOPTA. The number of the lesions detected by T1-weighted imaging, T2-weighted imaging, diffusion-weighted imaging, dynamic contrast-enhanced, and delayed hepatobiliary-phase imaging was counted, respectively. Contrast-to-noise ratios were measured for all the sequences including delayed hepatobiliary-phase imaging. The signal intensity and morphologic features of liver parenchyma and lesions were recorded and analyzed. RESULTS: There were 7 patients with hepatocellular carcinomas, 6 with hemangiomas, 7 with metastases, and 5 with cholangiocarcinomas. The delayed hepatobiliary-phase imaging showed a homogeneous enhancement of liver parenchyma and distinctive enhancement features of focal liver lesions. The delayed hepatobiliary-phase imaging was better than diffusion-weighted imaging for the detection of focal liver lesions (P < 0.05). CONCLUSION: The addition of hepatobiliary-phase imaging to Gd-BOPTA-enhanced dynamic imaging increased the sensitivity and accuracy for the detection of focal hepatic lesions.

[Effect of On-line NaClO Backwashing on Microbial Communities in an Inverted A2O-MBR System].

To study the effect of on-line NaClO backwashing on the microbial community structure of membrane bioreactor (MBR) systems, a reversed A2O-MBR reactor was used to monitor system performance, membrane fouling, and microbial community structure. Measurements were made during the stabilization stage, the on-line pure water backwashing stage, and the on-line NaClO backwashing stage. The results showed that key system performance indicators during NaClO backwashing stage, such as COD, ammonia nitrogen, and TN treatment efficiency, were similar to previous stages. The average membrane fouling rate during the on-line pure water backwashing period was lower than that of the stable stage, while the membrane fouling rate increased during the on-line NaClO backwashing stage, and EPS concentration was the highest and membrane fouling was aggravated. The results of the Chao index, Simpson index, and Shannon index showed that the microbial diversity in the aerobic tank sludge remained almost stable after on-line NaClO backwashing, while the abundance of cake layer sludge increased slightly, but the microbial diversity decreased significantly. Proteobacteria was the main microbial phylum in both the aerobic tank and cake layer sludge, followed by Bacteroidetes. After on-line NaClO backwashing, the relative abundance of Proteobacteria and Bacteroides in the aerobic tank sludge did not change notably, but the composition of filter cake sludge changed significantly. Proteobacteria that possess resistance to chlorine disinfectant increased from 53.4% to 77.8%, while Bacteroides decreased from 33.44% to 14.5%. After on-line NaClO backwashing, the composition of the microbial community in aerobic tank and cake layer was similar. Azospira and Comamonadaceaea also increased significantly after NaClO backwashing. Microbial species that can tolerate NaClO treatment may be the main cause of membrane fouling.