Acoustic structure quantification (ASQ) is a recently developed technique widely used for detecting liver fibrosis. Ultrasound Nakagami parametric imaging based on the Nakagami distribution has been widely used to model echo amplitude distribution for tissue characterization. We explored the feasibility of using ultrasound Nakagami imaging as a model-based ASQ technique for assessing liver fibrosis. Standard ultrasound examinations were performed on 19 healthy volunteers and 91 patients with chronic hepatitis B and C (n = 110). Liver biopsy and ultrasound Nakagami imaging analysis were conducted to compare the METAVIR score and Nakagami parameter. The diagnostic value of ultrasound Nakagami imaging was evaluated using receiver operating characteristic (ROC) curves. The Nakagami parameter obtained through ultrasound Nakagami imaging decreased with an increase in the METAVIR score (p < 0.0001), representing an increase in the extent of pre-Rayleigh statistics for echo amplitude distribution. The area under the ROC curve (AUROC) was 0.88 for the diagnosis of any degree of fibrosis (≥F1), whereas it was 0.84, 0.69, and 0.67 for ≥F2, ≥F3, and ≥F4, respectively. Ultrasound Nakagami imaging is a model-based ASQ technique that can be beneficial for the clinical diagnosis of early liver fibrosis.

Previously, the putative outer membrane protein STM3031 has been correlated with ceftriaxone resistance in Salmonella enterica serovar Typhimurium. In this study, this protein was almost undetectable in the ceftriaxone-susceptible strain 01-4, but its levels were increased in 01-4 isogenic strains for which MICs were higher. The stm3031 gene deletion mutant, R200(⌬stm3031), was generated and showed >64-fold lower ceftriaxone resistance than R200, supporting a key role for STM3031 in ceftriaxone resistance. To investigate which outer membrane protein(s) was associated with resistance, the outer membrane protein profiles of 01-4, R200, and R200(⌬stm3031) were compared proteomically. Nine proteins were identified as altered. The expression levels of AcrA, TolC, STM3031, STM1530, VacJ, and Psd in R200 were increased; those of OmpC, OmpD, and OmpW were decreased. The expression levels of OmpD, OmpW, STM1530, VacJ, and Psd, but not those of OmpC, AcrA, and TolC, in R200(⌬stm3031) were returned to the levels in strain 01-4. Furthermore, the genes' mRNA levels correlated with their protein levels when the three strains were compared. The detection of higher AcrB levels, linked to higher acrB, acrD, and acrF mRNA levels, in strain R200 than in strains 01-4 and R200(⌬stm3031) suggests that AcrB, AcrD, and AcrF participate in ceftriaxone resistance. Taken together with the location of STM3031 in the outer membrane, these results suggest that STM3031 plays a key role in ceftriaxone resistance, probably by reducing permeability via a decreased porin OmpD level and enhancing export via increased AcrD efflux pump activity.

Nonalcoholic fatty liver disease (NAFLD) is the leading cause of advanced liver diseases. Fat accumulation in the liver changes the hepatic microstructure and the corresponding statistics of ultrasound backscattered signals. Acoustic structure quantification (ASQ) is a typical model-based method for analyzing backscattered statistics. Shannon entropy, initially proposed in information theory, has been demonstrated as a more flexible solution for imaging and describing backscattered statistics without considering data distribution. NAFLD is a hepatic manifestation of metabolic syndrome (MetS). Therefore, we investigated the association between ultrasound entropy imaging of NAFLD and MetS for comparison with that obtained from ASQ. A total of 394 participants were recruited to undergo physical examinations and blood tests to diagnose MetS. Then, abdominal ultrasound screening of the liver was performed to calculate the ultrasonographic fatty liver indicator (US-FLI) as a measure of NAFLD severity. The ASQ analysis and ultrasound entropy parametric imaging were further constructed using the raw image data to calculate the focal disturbance (FD) ratio and entropy value, respectively. Tertiles were used to split the data of the FD ratio and entropy into three groups for statistical analysis. The correlation coefficient r, probability value p, and odds ratio (OR) were calculated. With an increase in the US-FLI, the entropy value increased (r = 0.713; p < 0.0001) and the FD ratio decreased (r = -0.630; p < 0.0001). In addition, the entropy value and FD ratio correlated with metabolic indices (p < 0.0001). After adjustment for confounding factors, entropy imaging (OR = 7.91, 95% confidence interval (CI): 0.96-65.18 for the second tertile; OR = 20.47, 95% CI: 2.48-168.67 for the third tertile; p = 0.0021) still provided a more significant link to the risk of MetS than did the FD ratio obtained from ASQ (OR = 0.55, 95% CI: 0.27-1.14 for the second tertile; OR = 0.42, 95% CI: 0.15-1.17 for the third tertile; p = 0.13). Thus, ultrasound entropy imaging can provide information on hepatic steatosis. In particular, ultrasound entropy imaging can describe the risk of MetS for individuals with NAFLD and is superior to the conventional ASQ technique.

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