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Background: Due to their location and growth patterns, retroperitoneal tumors often involve the surrounding blood vessels. Clinical decisions on a proper treatment depend on the information on this condition. Evaluation of blood vessels using non‐contrast‐enhanced vessel wall MRI may provide noninvasive assessment of the extent of tumor invasion to assist clinical decision‐making. Purpose: To investigate the performance and potential of non‐contrast‐enhanced vessel wall MRI in evaluating the degree of vessel wall invasion of retroperitoneal tumors. Study Type: Prospective. Population: Thirty‐seven participants (mean age: 60.59 ± 11.77 years, 59% male) with retroperitoneal tumors close to vessels based on their diagnostic computer tomography. Field Strength/Sequences: 3 T; vessel wall MRI sequences: two‐dimensional T2‐weighted MultiVane XD turbo spin‐echo (2D‐T2‐MVXD‐TSE) and three‐dimensional T1‐weighted motion sensitized driven equilibrium fat suppression turbo spin‐echo (3D‐T1‐MSDE‐TSE) sequences; conventional MRI sequences: T2‐weighted fat suppression turbo spin‐echo (T2‐FS‐TSE), T2‐weighted turbo spin‐echo (T2‐TSE), modified Dixon T1‐weighted fast field echo (T1‐mDixon‐FFE), and diffusion‐weighted echo planar imaging (DWI‐EPI) sequences. Assessment: All patients underwent preoperative imaging using both non‐contrast conventional and vessel wall MRI sequences. Images obtained from conventional and vessel wall MRI sequences were evaluated independently by three junior radiologists (3 and 2 years of experience in reading MRI) and reviewed by one senior radiologist (25 years of experience in reading MRI) to assess the degree of vessel wall invasion. MRI were validated results from the clinical standard diagnosis based on surgical confirmation or histopathological reports. Interobserver agreement was determined based on the reports from three readers with similar years of experiences. Intraobserver variability was assessed based on categorizing and recategorizing the vessels of 37 patients 1 month apart. Statistical Tests: Intra‐class correlation efficient (ICC), Chi‐square test, McNemar test, area under the receiver‐operating characteristic curve (AUC), Delong test, P < 0.05 was considered significant. Results: The accuracy of vessel wall MRI (91.96%, 95% CI: 85.43–95.71; 103 of 112) in detecting the degree of vessel wall invasion was significantly higher than that of conventional MRI (75%, 95% CI: 66.24–82.10; 84 of 112). The interobserver variability or reproducibility in categorization of the degree of vascular wall invasion was good in evaluating images from conventional and vessel wall MRI sequences (ICC = 0.821, 95% CI: 0.765–0.867 and ICC = 0.881, 95% CI: 0.842–0.913, respectively). Data Conclusion: Diagnosis of vessel wall invasion of retroperitoneal tumors and assessment of its severity can be improved by using non‐contrast‐enhanced vessel wall MRI. Evidence Level: 1 Technical Efficacy: Stage 3 [ABSTRACT FROM AUTHOR]

Purpose: To prospectively investigate age- and gender-related changes in the fast-twitch (tibialis anterior, TA) and slow-twitch (soleus, SOL) skeletal muscle of healthy rats and volunteers and to compare the exercise-related difference in health volunteers with T1 ρ magnetic resonance imaging (MRI).Materials and Methods: In all, 18 rats and 70 humans were involved in this study. For the animal study, T1 ρ relaxation times were measured in the TA and SOL rat muscle with a 3.0T MRI scanner and compared to histological data. For the human study, three groups (young, middle-aged, and elderly) of volunteers underwent T1 ρ MRI scans (3.0T) of their calves. To further differentiate the human scans, 18 volunteers were recruited, half of them (n = 9) routinely trained with high-intensity sports, while the other half (n = 9) with no physical training. Statistical analysis was performed via paired t-test, independent-sample t-test, and analysis of variance (ANOVA). Correlations between T1 ρ and age/gender/physical endurance were calculated.Results: The average T1 ρ relaxation times of the TA and SOL of female rats were higher than that of male rats (P < 0.001). The T1 ρ relaxation time of TA was significantly lower compared to SOL (P < 0.001). A significant linear correlation was observed between T1 ρ and the type I slow-twitch fiber proportion (%) in SOL (R2  = 0.837, P < 0.001). Similarly, in human studies the average T1 ρ relaxation times of TA were significantly lower than SOL for all age groups (P < 0.001). The higher T1 ρ relaxation times of TA and SOL in the elderly volunteers (P < 0.001) and in the females (P < 0.05) indicated significant age- and gender-dependent differences. In high-intensity sports groups, the higher T1 ρ in SOL (P < 0.01) and lower in TA (P < 0.05) were observed compared with the control group.Conclusion: This study demonstrated that T1 ρ MRI can be used to display the differences in fast- and slow-twitch skeletal muscle as well as potentially age-, gender-, and exercise-related differences.Level Of Evidence: 2 Technical Efficacy: Stage 1 J. MAGN. RESON. IMAGING 2017;46:61-70. [ABSTRACT FROM AUTHOR]

Aims We tested the hypothesis that endothelial progenitor cell ( EPC)-mediated functional recovery after stroke may be associated with the endothelial nitric oxide synthase (eNOS)/brain-derived neurotrophic factor ( BDNF) signaling pathway. Methods Mice were infused with either EPCs or saline after being subjected to middle cerebral artery occlusion. The EPC-treated mice also received intravenous injections of either Nω-nitro- l-arginine methyl ester (L- NAME, the NOS inhibitor) or saline. Results The activation of eNOS and the expression of BDNF were significantly increased in ischemic brain of the EPC-treated mice, along with increased angiogenesis and neurogenesis. On diffusion tensor imaging ( DTI), significant increases in fractional anisotropy and fiber count were observed in white matter, indicating axonal growth stimulated by EPCs. However, the EPC-treated mice that were received an L- NAME injection failed to exhibit the observed increases in angiogenesis, neurogenesis, and axonal growth. In addition, the neurons cocultured with EPCs in vitro exhibited the increased expression of BDNF and decreased apoptosis after oxygen-glucose deprivation compared with the control group. This EPC-induced protective effect was virtually absent in the L- NAME treatment group. Conclusion The eNOS/ BDNF pathway may be involved in the EPC-mediated functional recovery of stroke mice. DTI is feasible for dynamically tracking the orientation of axonal projections after EPC treatment. [ABSTRACT FROM AUTHOR]

BACKGROUND: Brain-metastatic breast cancer (BMBC) is increasing and poses a severe clinical problem because of the lack of effective treatments and because the underlying molecular mechanisms are largely unknown. Recent work has demonstrated that deregulation of epidermal growth factor receptor (EGFR) may correlate with BMBC progression. However, the exact contribution that EGFR makes to BMBC remains unclear. METHODS: The role of EGFR in BMBC was explored by serial analyses in a brain-trophic clone of human MDA-MB-231 breast carcinoma cells (231-BR cells). EGFR expression was inhibited by stable short-hairpin RNA transfection or by the kinase inhibitor erlotinib, and it was activated by heparin-binding epidermal growth factor-like growth factor (HB-EGF). Cell growth and invasion activities also were analyzed in vitro and in vivo. RESULTS: EGFR inhibition or activation strongly affected 231-BR cell migration/invasion activities as assessed by an adhesion assay, a wound-healing assay, a Boyden chamber invasion assay, and cytoskeleton staining. Also, EGFR inhibition significantly decreased brain metastases of 231-BR cells in vivo. Surprisingly, changes to EGFR expression affected cell proliferation activities less significantly as determined by a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, an anchorage-independent growth assay, and cell cycle analysis. Immunoblot analysis suggested that EGFR drives cells' invasiveness capability mainly through phosphoinositide 3-kinase/protein kinase B and phospholipase C γ downstream pathways. In addition, EGFR was involved less in proliferation because of the insensitivity of the downstream mitogen-activated protein kinase pathway. CONCLUSIONS: The current results indicated that EGFR plays more important roles in cell migration and invasion to the brain than in cell proliferation progression on 231-BR cells, providing new evidence of the potential value of EGFR inhibition in treating BMBC. Cancer 2012. © 2012 American Cancer Society. [ABSTRACT FROM AUTHOR]