Magnetic resonance imaging contrast agents are currently designed by modifying their structural and physiochemical properties in order to improve relaxivity and to enhance image contrast. Here we show a general method for increasing relaxivity by confining contrast agents inside the nanoporous structure of silicon particles. Magnevist, gadofullerenes and gadonanotubes were loaded inside the pores of quasi-hemispherical and discoidal particles. For all combinations of nanoconstructs, a boost in longitudinal proton relaxivity r1 was observed: for Magnevist, r1~14 mM-1s-1/Gd3+ion (~8.15×10+7 mM-1s-1/construct); for gadofullerenes, r1~200 mM-1s-1/Gd3+ion (~7×10+9 mM-1s-1/construct); for gadonanotubes, r1~150 mM-1s-1/Gd3+ion (~2×10+9 mM-1s-1/construct). These relaxivity values are about 4 to 50 times larger than that of clinically-available gadolinium-based agents (~4 mM-1s-1 /Gd3+ion). The enhancement in contrast is attributed to the geometrical confinement of the agents, which influences the paramagnetic behavior of the Gd3+ions. Thus, nanoscale confinement offers a new and general strategy for enhancing the contrast of gadolinium-based contrast agents.

Vitamin C deficiency is not uncommon in large pediatric health care facilities, and it is frequently missed on clinical evaluation and diagnostic imaging. At-risk populations include those with iron overload, neurologic conditions and history of chemotherapy. Scurvy related to dietary deficiency in otherwise normal children was not encountered. When characteristic MRI findings are seen, particularly in children with a predisposing condition for vitamin C deficiency, scurvy should be considered and a serum ascorbic acid level checked to potentially confirm a diagnosis prior to further invasive tests.

BackgroundCine balanced steady-state free precession (SSFP), the preferred sequence for ventricular function, demands uninterrupted radio frequency (RF) excitation to maintain the steady-state during suspended respiration. This is difficult to accomplish in sedated children. In this work, we validate a respiratory triggered (RT) SSFP sequence that drives the magnetization to steady-state before commencing retrospectively cardiac gated cine acquisition in a sedated pediatric population.MethodsThis prospective study was performed on 20 sedated children with congenital heart disease (8.6 ± 4 yrs). Identical imaging parameters were used for multiple number of signal averages (MN) and RT cine SSFP sequences covering both the ventricles in short-axis (SA) orientation. Image quality assessment and quantitative volumetric analysis was performed on the datasets by two blinded observers. One-sided Wilcoxon signed rank test and Box plot analysis were performed to compare the clinical scores. Bland-Altman (BA) analysis was performed on LV and RV volumes.ResultsScan duration for SA stack using RT-SSFP (3.9 ± 0.8 min) was slightly shorter than MN-SSFP (4.6 ± 0.9 min) acquisitions. The endocardial edge definition was significantly better for RT than MN, blood to myocardial contrast was better for RT than MN without reaching statistical significance, and inter slice alignment was comparable. BA analysis indicates that the variability of volumetric indices between RT and MN is comparable to inter and intra-observer variability reported in the literature.ConclusionsThe free breathing RT-SSFP sequence allows diagnostic images in sedated children with significantly better edge definition when compared to MN-SSFP, without any penalty for total scan time.

We examined the effects of combined pioglitazone (peroxisome proliferator-activated receptor-γ (PPAR-γ) agonist) and exenatide (GLP-1 receptor agonist) therapy on hepatic fat content and plasma adiponectin levels in patients with type 2 diabetes (T2DM). Twenty-one T2DM patients (age = 52 ± 3 years, BMI = 32.0 ± 1.5, hemoglobin A 1c (HbA 1c ) = 8.2 ± 0.4%) on diet and/or metformin received additional treatment with either pioglitazone 45 mg/day for 12 months (n = 10) or combined therapy with pioglitazone (45 mg/day) and exenatide (10 µg subcutaneously twice daily) for 12 months (n = 11). At baseline, hepatic fat content and plasma adiponectin levels were similar between the two treatment groups. Pioglitazone reduced fasting plasma glucose (FPG) (P < 0.05), fasting free fatty acid (FFA) (P < 0.05), and HbA 1c (Δ = 1.0%, P < 0.01), while increasing plasma adiponectin concentration by 86% (P < 0.05). Hepatic fat (magnetic resonance spectroscopy (MRS)) was significantly reduced following pioglitazone treatment (11.0 ± 3.1 to 6.5 ± 1.9%, P < 0.05). Plasma triglyceride concentration decreased by 14% (P < 0.05) and body weight increased significantly (Δ = 3.7 kg). Combined pioglitazone and exenatide therapy was associated with a significantly greater increase in plasma adiponectin (Δ = 193%) and a significantly greater decrease in hepatic fat (12.1 ± 1.7 to 4.7 ± 1.3%) and plasma triglyceride (38%) vs. pioglitazone therapy despite the lack of a significant change in body weight (Δ = 0.2 kg). Hepatic injury biomarkers aspartate aminotransferase and alanine aminotransferase (ALT) were significantly decreased by both treatments; however, the reduction in ALT was significantly greater following combined pioglitazone and exenatide therapy. We conclude that combined in patients with T2DM, pioglitazone and exenatide therapy is associated with a greater reduction in hepatic fat content as compared to the addition of pioglitazone therapy (Δ = 61% vs. 41%, P < 0.05).