Robert P Thomen

Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, United States

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Publications (4)9.61 Total impact

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    ABSTRACT: Purpose To quantify regional lung ventilation in healthy volunteers and patients with severe asthma (both before and after thermoplasty) by using a combination of helium 3 ((3)He) magnetic resonance (MR) imaging and computed tomography (CT), with the intention of developing more effective image-guided treatments for obstructive lung diseases. Materials and Methods With approval of the local institutional review board, informed consent, and an Investigational New Drug Exemption, six healthy volunteers and 10 patients with severe asthma were imaged in compliance with HIPAA regulations by using both multidetector CT and (3)He MR imaging. Individual bronchopulmonary segments were labeled voxel by voxel from the CT images and then registered to the (3)He MR images by using custom software. The (3)He signal intensity was then analyzed by evaluating the volume-weighted fraction of total-lung signal intensity present in each segment (segmental ventilation percentage [SVP]) and by identifying the whole-lung defect percentage and the segmental defect percentage. Of the 10 patients with asthma, seven received treatment with bronchial thermoplasty and were imaged with (3)He MR a second time. Changes in segmental defect percentages and whole-lung defect percentages are presented. Results Ventilation measures for healthy volunteers yielded smaller segment-to-segment variation (mean SVP, 100% ± 18 [standard deviation]) than did the measures for patients with severe asthma (mean SVP, 97% ± 23). Patients with asthma also demonstrated larger segmental defect percentages (median, 13.5%; interquartile range, 8.9%-17.8%) than healthy volunteers (median, 6%; interquartile range, 5.6%-6.3%). These quantitative results confirm what is visually observed on the (3)He images. A Spearman correlation of r = -0.82 was found between the change in whole-lung defect percentage and the number of days between final treatment and second (3)He imaging. Conclusion Regional quantification of lung ventilation is indeed feasible and may be a useful technique for image-guided treatment of obstructive lung diseases, such as bronchial thermoplasty for severe asthma. In these patients, ventilation defects decreased as a function of time after treatment. © RSNA, 2014 Online supplemental material is available for this article.
    Radiology 08/2014; · 6.34 Impact Factor
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    ABSTRACT: To demonstrate that longitudinal, noninvasive monitoring via MRI can characterize acute cellular rejection in mouse orthotopic lung allografts.
    Magnetic Resonance in Medicine 06/2014; · 3.27 Impact Factor
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    ABSTRACT: The performance of prototypes for the ALICE electromagnetic sampling calorimeter has been studied in test beam measurements at FNAL and CERN. A 4×4 array of final design modules showed an energy resolution of about with a uniformity of the response to electrons of 1% and a good linearity in the energy range from 10 to 100 GeV. The electromagnetic shower position resolution was found to be described by . For an electron identification efficiency of 90% a hadron rejection factor of >600 was obtained.
    Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. 01/2010;
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    ABSTRACT: The ALICE ITS Alignment Monitoring System, ITSAMS, is a simple geometrical optics system using off-the-shelf CMOS cameras and USB communication protocols. The system consists of four spherical mirrors and four camera modules, with each camera module containing a USB camera with a 1280×1024 pixel CMOS array, a 0.8 mW laser diode light source, a fiber optic collimator, and an electronics driver board. The laser diode's light is collimated into a beam and projected onto a spherical mirror which has a focal point located on the camera's imager and then focuses the beam back onto the camera module's CMOS array. A movement of either the mirror or the camera causes the beam spot on the CMOS array to move the same distance. The resolution of relative movement between the two modules is found to be approximately 70 microns in the plane perpendicular to the beam axis, 610 microns, along the beam axis, 0.77 millidegrees for rotations about the transverse axes, and 3.13 millidegrees for a rotation about the beam axis.