Traditional methods of quantitative analysis of CT images typically involve working with patient data, which is often expensive and limited in terms of ground truth. To counter these restrictions, quantitative assessments can instead be made through Virtual Imaging Trials (VITs) which simulate the CT imaging process. This study sought to validate DukeSim (a scanner-specific CT simulator) utilizing clinically relevant biomarkers for a customized anthropomorphic chest phantom. The physical phantom was imaged utilizing two commercial CT scanners (Siemens Somatom Force and Definition Flash) with varying imaging parameters. A computational version of the phantom was simulated utilizing DukeSim for each corresponding real acquisition. Biomarkers were computed and compared between the real and virtually acquired CT images to assess the validity of DukeSim. The simulated images closely matched the real images both qualitatively and quantitatively, with the average biomarker percent difference of 3.84% (range 0.19% to 18.27%). Results showed that DukeSim is reasonably well validated across various patient imaging conditions and scanners, which indicates the utility of DukeSim for further VIT studies where real patient data may not be feasible.
CT imaging provides physicians valuable insights when diagnosing disease in a clinical setting. In order to provide an accurate diagnosis, is it important to have a high accuracy with controlled variability across CT scans from different scanners and imaging parameters. The purpose of this study was to analyze variability of lung imaging biomarkers across various scanners and parameters using a customized version of a commercially available anthropomorphic chest Phantom (Kyoto Kagaku) with several experimental sample inserts. The phantom was across 10 different CT scanners with a total of 209 imaging conditions. An algorithm was developed to compute different imaging biomarkers. Variability across images from the same scanner and from different scanners was analyzed by computing coefficients of variation (CV) and standard deviations of HU values. LAA -950 and LAA -856 biomarkers had the highest levels of variability, while the majority of other biomarkers had variability less than 10 HU or 10% CV in both inter and intrascan measurements. There was no clear trend present between the biomarker measurements and CTDIvol. The results of this study demonstrates the existing variability in CT quantifications for lung imaging, which prompt further studies on how to reduce such variation.
Significance: Infrared (IR) inhibition can selectively block peripheral sensory nerve fibers, a potential treatment for autonomic-dysfunction-related diseases (e.g., neuropathic pain and interstitial cystitis). Lowering the IR inhibition threshold can increase its translational potentials.
Aim: Infrared induces inhibition by enhancing potassium channel activation. We hypothesized that the IR dose threshold could be reduced by combining it with isotonic ion replacement.
Approach: We tested the IR inhibition threshold on the pleural-abdominal connective of Aplysia californica. Using a customized chamber system, the IR inhibition was applied either in normal saline or in isotonic ion-replaced saline, which could be high glucose saline, high choline saline, or high glucose/high choline saline. Each modified saline was at a subthreshold concentration for inhibiting neural conduction.
Results: We showed that isotonically replacing ions in saline with glucose and/or choline can reduce the IR threshold and temperature threshold of neural inhibition. Furthermore, the size selectivity of IR inhibition was preserved when combined with high glucose/high choline saline.
Conclusions: The present work of IR inhibition combined with isotonic ion replacement will guide further development of a more effective size-selective IR inhibition modality for future research and translational applications.
Neuromodulation has the potential to treat various diseases (i.e., heart failure, obesity). Several clinical trials have recently failed because of the inability to modulate small-diameter fibers. Previously, we demonstrated preferential inhibition of small-diameter fibers using infrared neuromodulation (IRN). To understand the mechanism of action, we did a mathematical analysis which suggested that any modality acting primarily on the axonal surface would preferentially affect small-diameter axons. To test our hypothesis, we examined whether isotonic glucose solution would give results similar to IRN.
We stimulated the left and right pleural-abdominal connective nerves of Aplysia californica and recorded the resulting compound action potentials (CAPs). We designed a chamber with three isolated compartments through which the nerve passes sequentially. Aplysia saline is perfused in the two outer chambers while the middle chamber can be perfused with either Aplysia saline or an isotonic glucose solution (10.21 w/v %). The width of the middle chamber is adjustable to vary the length of nerve perfused by the isotonic glucose solution. As the length of the middle chamber increases, recorded CAPs are initially unaffected, then show a loss of peaks representing small-diameter axons, then show no activity. We can restore full, unchanged CAPs by washing out the glucose solution and replacing it with Aplysia saline. These results support the hypothesis that any modality (e.g., both IRN and isotonic glucose solution) acting primarily on the axonal surface would preferentially affect small-diameter axons. Future studies will compare IRN with isotonic glucose block.
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