Background: Photoacoustic imaging (PAI) provides real-time noninvasive and contrast agent-free monitoring of the concentrations of some endogenous compounds related to tumor vascularization and oxygenation. In this study, we used PAI to noninvasively evaluate tumor responses to antiangiogenic therapy. Methods: In vivo studies were performed with the approval of our institutional animal ethics committee. We used a xenograft mouse model of 4T1 breast cancer treated with different doses of bevacizumab or vehicle. Seven days after implantation, tumor-bearing mice (with tumors ~5–8 mm diameter) were randomly divided into low-dose (10 mg/kg), high-dose (20 mg/kg) and vehicle groups (same dose of saline). Each experimental group was administered bevacizumab intraperitoneally only once. Before and after treatment, acoustic resolution-photoacoustic microscopy (AR-PAM), a type of PAI, was conducted in vivo consecutively from day 1 to day 5. PAI-derived quantitative parameters were calculated at each time point. Additional cohorts of mice were used to quantify CD31 and hypoxia by immunohistochemical assays. Results: The values of the PAI parameters were not significantly different among the experimental and control groups at the same time point before treatment (all P>0.05). The total hemoglobin (HbT) levels in the treatment group gradually decreased from day 1 to day 2 (relative to those in the control group, P>0.05) and decreased significantly relative to those in the control group from day 3 to day 5 (P<0.05). The deoxyhemoglobin (HbR) levels in the treatment group decreased from day 1 to 5 after treatment. The high-dose group had significantly decreased HbR levels relative to the control group from day 1 to 5 (P<0.05). The low-dose group also showed a gradual and significant decrease in HbR levels on day 3 (P<0.05). CD31 was decreased in the low-dose group relative to the control group on day 1 (decreased by 34.05%, P=0.067) and day 3 (decreased by 45.27%, P=0.180), and the decrease in CD31 persisted on day 5 (decreased by 71.41%, P=0.000). CD31 decreased to a greater extent in the high-dose group than in the low-dose group. Tumor hypoxia was significantly increased on day 1 from day 0 in the treatment groups (P<0.05), especially in the high-dose group. Hypoxia was decreased on days 3 and 5 in the low-dose group (10.92±0.92 and 8.17±1.9, P=0.317) but continuously increased over time in the high-dose group. Significantly greater hypoxia was observed in the high-dose group than in the low-dose group (17.60±1.20 and 20.33±0.47, P<0.05). Conclusions: PAI can be used to evaluate both vessel regression and hypoxia in response to anti-vascular treatment.

It is crucial to explore the pathogenesis of major depressive disorder (MDD) at the early stage for the better diagnostic and treatment strategies. It was suggested that MDD might be involving in functional or structural alternations at the brain network-level. However, at the onset of MDD, whether the whole brain white matter (WM) alterations at network-level are already evident still remains unclear. In the present study, diffusion MRI scanning was adopt to depict the unique WM structural network topology across the entire brain at the early stage of MDD. Twenty-one first episode, short duration (<1 year) and drug-naïve depression patients, and 25 healthy control subjects (HCs) were recruited. To construct the WM structural network, atlas-based brain regions were used for nodes, and the value of multiplying fiber number (FN) by the mean FA along the fiber bundles connected a pair of brain regions were used for edges. The structural network was analyzed by graph theoretic and Network-Based Statistic (NBS) methods. Pearson partial correlation analysis was also performed to evaluate their correlation with the clinical variables. Compared with healthy controls, the MDD patients had a significant decrease in the small-worldness (σ). Meanwhile, the MDD patients presented a significantly decreased subnetwork, which mainly involved in the frontal-subcortical and limbic regions. Our results suggested that the abnormal structural network of the OFC and thalamus, involving the imbalance with the limbic system, might be a key pathology in early stage drug-naive depression. And the structural network analysis might be potential in early detection and diagnosis of MDD.

Background: Our study aimed to investigate the feasibility of functional magnetic resonance imaging [blood oxygen level-dependent (BOLD) imaging and T2 mapping] in monitoring the activation of lumbar paraspinal muscles before and after exercise. Methods: The ethics committee of the First Affiliated Hospital of Kunming Medical University approved our study. Both BOLD and T2 mapping of paraspinal muscles were performed in 50 healthy, young volunteers before and after upper-body extension exercises. The movement tasks included upper body flexion and extension using a simple Roman chair. Cross-sectional area (CSA), R2*, and T2 values were measured in various lower-back anatomical regions. The SPSS22.0 statistical software was used to analyze all the data. Results: Post-exercise CSA and T2 values were higher than those recorded in the pre-exercise session for the three lower-back muscles that were evaluated (iliocostalis, longissimus, and multifidus) (P<0.01). However, R2* values of these muscles were significantly lower after exercise (P<0.01). A significant difference in the R2*, CSA, and T2 values of the iliocostalis occurred between males and females (P<0.05). No statistically significant differences were evident for R2*, CSA, and T2 of the lower-back muscles between L3 and L4 levels, or between the left and right sides. The total CSA of the iliocostalis was higher than that of the multifidus and longissimus (P<0.05). Conclusions: BOLD and T2 mapping are feasible non-invasive indirect assessments of lumbar paraspinal muscle activation before and after exercise.