λ-Eye: A high-sensitivity γ imaging probe for axillary sentinel lymph node mapping

Objective The aim of this study is the construction and performance evaluation of γ-eye, a γ imaging probe, optimized in terms of sensitivity for sentinel lymph node mapping. The optimization of the probe is based on theoretical models and simulation results that were presented in a previous study of our group. In this work, the construction of the probe, the experimental confirmation of the simulation results, and the evaluation of its performance with phantoms and lymph node imaging in small animals are presented. Methods The systems spatial and energy resolution, sensitivity, and count rate performance were measured using phantoms. The values of the integral and differential uniformity in the useful field-of-view and in the central fieldof-view were also calculated. Finally, a proof-of-concept animal experiment was conducted for the imaging of the lymph nodes of normal mice. Results The systems energy resolution was measured as 36± 2% and the spatial resolution was 2.2mm at 2mm source-collimator distance. The values of the integral uniformity and differential uniformity in the useful field-ofview and in the central field-of-view were found to be 5.2, 2.1, 1.7, and 0.75%, respectively. Finally, the lymph nodes of normal mice were clearly imaged with a 10 s acquisition time. Conclusion The γ-eye, used for sentinel lymph node mapping, provides a combination of high sensitivity (∼1.5 counts/s/kBq) and good spatial resolution (∼6mm full-width of the half-maximum at 20mm and ∼10mm fullwidth of the half-maximum at 50mm distance). Its compact size (40mm×40mm×70 mm) allows its use during surgery and/or for the detailed scan of a suspicious region. © 2016 Wolters Kluwer Health, Inc. All rights reserved

Evaluation of an imaging gamma probe based on R8900U-00-C12 PSPMT

In this study we present the construction and the evaluation of a gamma probe based on a R8900U-00-C12 position sensitive photomultiplier tube coupled to a pixelated CsI(Tl) crystal array with 2mm x 2mm x 3mm crystal elements and a general purpose parallel collimator. Sensitivity, energy resolution and spatial resolution were measured under 140keV irradiation, using Tc 99m. Spatial resolution was found equal to 2.4mm at zero source to collimator distance, while the sensitivity was 120cps/MBq and the energy resolution equal to 16%. Following its construction and experimental validation, the probe was simulated in GATE toolkit (version 6.0). Simulation studies were carried towards the determination of the optimal collimator that will show best compromise between high sensitivity and spatial resolution. © 2011 IEEE

An essential function for autocrine hedgehog signaling in epithelial proliferation and differentiation in the trachea

The tracheal epithelium is a primary target for pulmonary diseases as it provides a conduit for air flow between the environment and the lung lobes. The cellular and molecular mechanisms underlying airway epithelial cell proliferation and differentiation remain poorly understood. Hedgehog (HH) signaling orchestrates communication between epithelial and mesenchymal cells in the lung, where it modulates stromal cell proliferation, differentiation and signaling back to the epithelium. Here, we reveal a previously unreported autocrine function of HH signaling in airway epithelial cells. Epithelial cell depletion of the ligand sonic hedgehog (SHH) or its effector smoothened (SMO) causes defects in both epithelial cell proliferation and differentiation. In cultured primary human airway epithelial cells, HH signaling inhibition also hampers cell proliferation and differentiation. Epithelial HH function is mediated, at least in part, through transcriptional activation, as HH signaling inhibition leads to downregulation of cell type-specific transcription factor genes in both the mouse trachea and human airway epithelial cells. These results provide new insights into the role of HH signaling in epithelial cell proliferation and differentiation during airway development