Q-space imaging based on Gaussian radial basis function with Laplace regularization.

PURPOSE: To introduce the diffusion signal characteristics presented by spherical harmonics (SH) basis into the q-space imaging method based on Gaussian radial basis function (GRBF) to robustly reconstruct ensemble average diffusion propagator (EAP) in diffusion MRI (dMRI). METHODS: We introduced the Laplacian regularization of the signal into the dMRI imaging method based on GRBF, and derived the relevant indicators of microstructure imaging and the orientation distribution function (ODF) providing fiber bundle direction information based on EAP. In addition, this method is combined with a multi-compartment model to calculate the diameter of fiber bundle axons. The evaluation of the results included qualitative comparisons and quantitative assessments of the signal fitting. RESULTS: The results show that the proposed method achieves the more significant accuracy improvement in reconstructing signal. Meanwhile, ODFs estimated by the proposed method show the sharper profiles and less spurious peaks, even under the sparse and noisy conditions. In the 36 sets of axon diameter estimation experiments, 34 and 30 sets of results showed that the proposed method reduced the mean and SD of axon diameter estimates, respectively. Moreover, compared with the current state-of-the-art method, the mean and SD of axon diameter estimated by the proposed method are mostly lower, with 32 and 29 of 36 groups. CONCLUSION: The proposed method outperforms the GRBF regarding signal fitting and the estimation of the EAP and ODF with multi-shell sparse samples. Moreover, it shows the potential to recover important features of microstructures with less uncertainty by using proposed method together with multi-compartment models.

Superficial white matter microstructural imaging method based on time-space fractional-order diffusion.

Objective. Microstructure imaging based on diffusion magnetic resonance signal is an advanced imaging technique that enablesin vivomapping of the brain's microstructure. Superficial white matter (SWM) plays an important role in brain development, maturation, and aging, while fewer microstructure imaging methods address the SWM due to its complexity. Therefore, this study aims to develop a diffusion propagation model to investigate the microstructural characteristics of the SWM region.Approach. In this paper, we hypothesize that the effect of cell membrane permeability and the water exchange between soma and dendrites cannot be neglected for typical clinical diffusion times (20 ms

Clinical Application of Cardiac Magnetic Resonance in ART-Treated AIDS Males with Short Disease Duration.

Cardiac complications are common in antiretroviral therapy-treated (ART-treated) acquired immune deficiency syndrome (AIDS) patients, and the incidence increases with age. Myocardial injury in ART-treated AIDS patients with a relatively longer disease duration has been evaluated. However, there is no relevant study on whether patients with a short AIDS duration have cardiac dysfunction. Thirty-seven ART-treated males with AIDS and eighteen healthy controls (HCs) were prospectively included for CMR scanning. Clinical data and laboratory examination results were collected. The ART-treated males with AIDS did not have significantly reduced biventricular ejection fraction, myocardial edema, or late gadolinium enhancement. Compared with the HCs, the biventricular volume parameters and left ventricle myocardial strain indices in ART-treated males with AIDS were not significantly reduced (all p > 0.05). ART-treated males with AIDS were divided into subgroups according to their CD4+ T-cell counts (<350 cells/µL and ≥350 cells/µL) and duration of disease (1−12 months, 13−24 months, and 25−36 months). There was no significant decrease in left or right ventricular volume parameters or myocardial strain indices among the subgroups (all p > 0.05). In Pearson correlation analysis, CD4+ T-cell counts were not significantly correlated with biventricular volume parameters or left ventricular myocardial strain indices. In conclusion, ART-treated males with AIDS receiving ART therapy with a short disease duration (less than 3 years) might not develop obvious cardiac dysfunction as evaluated by routine CMR, so it is reasonable to appropriately extend the interval between cardiovascular follow-ups to more than 3 years.

Hydrocarbon degradation and bioemulsifier production by thermophilic Geobacillus pallidus strains.

Geobacillus pallidus XS2 and XS3 were isolated from oil contaminated soil samples in Yumen oilfield, China, and were able to produce bioemulsifiers on different hydrocarbons. Biodegradation assays exhibited that approximately 70% of PAH (250 mg/L) or 85% of crude oil (500 mg/L) was removed by the thermophilic bacteria after 20 days. The bioemulsifiers of the two strains were isolated and obtained a productive yield of 4.24±0.08 and 3.82±0.11g/L, respectively. GPC analysis revealed that the number-average molecular weights (M(n)) of the two bioemulsifiers were 271,785 Da and 526,369 Da, with PDI values of 1.104 and 1.027, respectively. Chemical composition studies exhibited that the bioemulsifier XS2 consisted of carbohydrates (68.6%), lipids (22.7%) and proteins (8.7%) while the bioemulsifier XS3 was composed by carbohydrates (41.1%), lipids (47.6%) and proteins (11.3%). Emulsification assays approved the effectiveness of bioemulsifiers over a wide range of temperature, pH and salinity.