Experimental feasibility of multi-energy photon-counting K-edge imaging in pre-clinical computed tomography.

Theoretical considerations predicted the feasibility of K-edge x-ray computed tomography (CT) imaging using energy discriminating detectors with more than two energy bins. This technique enables material-specific imaging in CT, which in combination with high-Z element based contrast agents, opens up possibilities for new medical applications. In this paper, we present a CT system with energy detection capabilities, which was used to demonstrate the feasibility of quantitative K-edge CT imaging experimentally. A phantom was imaged containing PMMA, calcium-hydroxyapatite, water and two contrast agents based on iodine and gadolinium, respectively. Separate images of the attenuation by photoelectric absorption and Compton scattering were reconstructed from energy-resolved projection data using maximum-likelihood basis-component decomposition. The data analysis further enabled the display of images of the individual contrast agents and their concentrations, separated from the anatomical background. Measured concentrations of iodine and gadolinium were in good agreement with the actual concentrations. Prior to the tomographic measurements, the detector response functions for monochromatic illumination using synchrotron radiation were determined in the energy range 25 keV-60 keV. These data were used to calibrate the detector and derive a phenomenological model for the detector response and the energy bin sensitivities.

Measurement of helicity-dependent photoabsorption cross sections on the neutron from 815 to 1825 MeV.

Helicity-dependent total photoabsorption cross sections on the deuteron have been measured for the first time at ELSA (Bonn) in the photon energy range from 815 to 1825 MeV. Circularly polarized tagged photons impinging on a longitudinally polarized LiD target have been used together with a highly efficient 4pi detector system. The data around 1 GeV are not compatible with predictions from existing multipole analyses. From the measured energy range an experimental contribution to the GDH integral on the neutron of [33.9 +/- 5.5(stat) +/- 4.5(syst)] microb is extracted.

Experimental check of the Gerasimov-Drell-Hearn sum rule for 1H.

For the first time we checked the fundamental Gerasimov-Drell-Hearn (GDH) sum rule for the proton experimentally in the photon energy range from 0.2-2.9 GeV with the tagged photon facilities at MAMI (Mainz) and ELSA (Bonn). New data of the doubly polarized total cross section difference are presented in the energy range from 1.6 to 2.9 GeV. The contribution to the GDH integral from 0.2-2.9 GeV yields [254+/-5(stat)+/-12(syst)] microb with negative contributions in the Regge regime at photon energies above 2.1 GeV. This trend supports the validity of the GDH sum rule.

First Measurement of the Gerasimov-Drell-Hearn Sum Rule for 1H from 0.7 to 1.8 GeV at ELSA.

To verify the fundamental Gerasimov-Drell-Hearn (GDH) sum rule for the first time experimentally, we measured the helicity dependent total photoabsorption cross section with circularly polarized real photons and longitudinally polarized nucleons in the photon energy range 0.68-1.82 GeV with the tagged photon facility at ELSA. The experiment was carried out with a 4pi detection system, a circularly polarized tagged photon beam, and a frozen spin polarized proton target. The contribution to the GDH sum rule in this photon energy range is [49.9+/-2.4(stat)+/-2.2(syst)] microb.

Psychological and symptom distress in terminal cancer patients with met and unmet needs.

This study identified the needs of terminal cancer patients, investigated the factors associated with unmet needs, and assessed psychological and symptom distress associated with unsolved needs. Ninety-four patients were randomly selected from 324 patients admitted for palliative care in 13 Italian centers. Two self-administered questionnaires (the Symptom Distress Scale and the Psychological Distress Inventory) were administered to all the patients. Patients needs were identified using a semi-structured interview, aimed at exploring five areas: physiological needs, safety needs, love and belonging needs, self-esteem needs, self-fulfillment needs. A content analysis of the answers defined 11 needs, and identified patients with unmet needs. The most frequent unmet needs were symptom control (62.8%), occupational functioning (62.1%), and emotional support (51.7%). The less frequently reported needs were those related to personal care (14.6%), financial support (14.1%), and emotional closeness (13.8%). Low functional state was significantly associated with a high proportion of patients with unmet needs of personal care, information, communication, occupational functioning, and emotional closeness. Patients with unmet needs showed significantly higher psychological and symptom distress for most needs. This study provides some suggestions about the concerns that should be carefully considered during the late stage of cancer.

Positive inotropic effects of the beta 2-adrenoceptor agonist terbutaline in the human heart: effects of long-term beta 1-adrenoceptor antagonist treatment.

OBJECTIVES: This study was conducted to determine whether activation of cardiac beta 2-adrenoceptors increases contractility in humans and whether this is affected by long-term beta 1-adrenoceptor antagonist treatment. BACKGROUND: Coexistence of beta 1- and beta 2-adrenoceptors in the human heart is generally accepted. The functional importance of cardiac beta 2-adrenoceptors for increases in contractility in humans, however, has not been completely established. METHODS: We studied 1) the beta-adrenoceptor subtype mediating positive inotropic effects of the beta 2-adrenoceptor agonist terbutaline in vitro (on right atrial and left ventricular preparations from nonfailing human hearts) and increases in contractility (by measurement of systolic time intervals) in vivo in seven healthy male volunteers; and 2) in vivo whether long-term treatment of volunteers with the beta 1-adrenoceptor antagonist bisoprolol affects terbutaline-induced increases in contractility. RESULTS: In vitro terbutaline caused a concentration-dependent increase in atrial and ventricular adenylate cyclase activity and force of contraction. Terbutaline effects were antagonized only by the beta 2-adrenoceptor antagonist ICI 118,551, indicating that they were mediated by beta 2-adrenoceptor stimulation. In vivo intravenous infusions of terbutaline (dose range 25 to 300 ng/kg body weight per min for 15 min) dose dependently increased heart rate and shortened the pre-ejection period and heart rate-corrected electromechanical systole (QS2) time. These effects are mediated predominantly by beta 2-adrenoceptor stimulation because they were only marginally affected by the beta 1-adrenoceptor antagonist bisoprolol (1 x 10 mg orally), either given 2 h before infusion or long term for 3 weeks. CONCLUSIONS: Stimulation of cardiac beta 2-adrenoceptors in humans causes not only in vitro but also in vivo positive inotropic effects. Long-term beta 1-adrenoceptor antagonist treatment does not considerably affect beta 2-adrenoceptor-mediated in vivo increases in contractility. Thus, it may be possible to treat patients with chronic heart failure and long-term beta 1-adrenoceptor antagonist therapy with beta 2-adrenoceptor agonists if immediate inotropic support is needed.