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Rationale and Objectives In this study, we compared a newly developed multibreath simultaneous alveolar oxygen tension and apparent diffusion coefficient (PAO2-ADC) imaging sequence to a single-breath acquisition, with the aim of mitigating the compromising effects of intervoxel flow and slow-filling regions on single-breath measurements, especially in chronic obstructive pulmonary disease (COPD) subjects. Materials and Methods Both single-breath and multibreath simultaneous PAO2-ADC imaging schemes were performed on a total of 10 human subjects (five asymptomatic smokers and five COPD subjects). Estimated PAO2 and ADC values derived from the different sequences were compared both globally and regionally. The distribution of voxels with nonphysiological values was also compared between the two schemes. Results The multibreath protocol decreased the ventilation defect volumes by an average of 12.9 ± 6.6%. The multibreath sequence generated nonphysiological PAO2 values in 11.0 ± 8.5% fewer voxels than the single-breath sequence. Single-breath PAO2 maps also showed more regions with gas-flow artifacts and general signal heterogeneity. On average, the standard deviation of the PAO2 distribution was 16.5 ± 7.0% lower using multibreath PAO2-ADC imaging, suggesting a more homogeneous gas distribution. Both mean and standard deviation of the ADC increased significantly from single- to multibreath imaging (p = 0.048 and p = 0.070, respectively), suggesting more emphysematous regions in the slow-filling lung. Conclusion Multibreath PAO2-ADC imaging provides superior accuracy and efficiency compared to previous imaging protocols. PAO2 and ADC maps generated by multibreath imaging allowed for the qualification of various regions as emphysematous or obstructed, which single-breath PAO2 maps can only identify as defects. The simultaneous PAO2 and ADC measurements generated by the presented multibreath method were also more physiologically realistic, and allowed for more detailed analysis of the slow-filling regions characteristic of COPD subjects.

Dynamic nuclear polarization (DNP) of (15)N2O, known for its long-lived singlet-state order at low magnetic field, is demonstrated in organic solvent/trityl mixtures at ∼1.5 K and 5 T. Both (15)N polarization and intermolecular dipolar broadening are strongly affected by the sample's thermal history, indicating spontaneous formation of N2O clusters. In situ (15)N NMR reveals four distinct powder-pattern spectra, attributed to the chemical-shift anisotropy (CSA) tensors of the two (15)N nuclei, further split by the intramolecular dipolar coupling between their magnetic moments. (15)N polarization is estimated by fitting the free-induction decay (FID) signals to the analytical model of four single-quantum transitions. This analysis implies (10.2±2.2)% polarization after 37 h of DNP, and provides a direct, instantaneous probe of the absolute (15)N polarization, without a need for time-consuming referencing to a thermal-equilibrium NMR signal.

an N1-S1 hepatocellular carcinoma in a rat model. Materials and Methods: 24 rats with implanted liver N1S1 tumors were divided into 4 groups: control group (n1⁄45, 1 mL normal saline, NS), bland embolization group (TAE, n1⁄44, 10 mg 50-150 micron PVA in 1 mL NS), TAE and caffeic acid group (TAEþCA, n1⁄45, 10mg PVA and 30 mg of caffeic acid in 1 mL NS), and TAE and ferulic acid group (TAEþFA, n1⁄45, 10 mg PVA and 30 mg ferulic acid in 1 mL NS). Embolization was through retrograde catheterization of the gastroduodenal artery and verified through contrast-enhanced ultrasound (CE-US). Tumor volume was measured by US before and twice a week until 4 weeks post-treatment. The repeated measures ANOVA was used to compare differences in pre-treatment tumor volume by group and over time. At 4 weeks, the rats were sacrificed and histopathologic evaluation performed. Results: There was no significant difference in the initial tumor sizes between each group. The control group showed rapid growth with a volume that was 3,000% larger compared with baseline. In the TAE group, tumor volume increased when compared to pre-treatment volume by 6.7 þ/-11.2%. Both TAEþCA and TAEþFA demonstrated a statistically significant decrease in tumor size when compared to TAE with a decrease in tumor volume by 86.8þ/-10.2% and 71.8þ/10.5%, respectively (po0.0001). Histopathogic evaluation showed marked decreases in amounts of residual tumor and inflammatory changes in the caffeic acid and ferulic acid groups when compared to the TAE group. Conclusion: Embolization with PVA and caffeic acid or ferulic acid provides a statistically significant improved tumor response compared to PVA alone in a rat N1S1 tumor model. Combination treatment through inhibition of both aerobic metabolism through embolization and inhibtion of anaerobic metabolism through lactate transport inhibition is a viable and effective treatment approach that shows great promise.