This study described and validated a new solid-state singlephoton g-camera and compared it with a conventional-SPECT Anger camera. The compact new camera uses a unique method for localizing g-photon information with a bank of 9 solid-state detector columns with tungsten collimators that rotate independently. Methods: Several phantom studies were performed comparing the new technology with conventional-SPECT technology. These included measurements of line sources and single-and dual-radionuclide studies of a torso phantom. Simulations were also performed using a cardiothoracic phantom. Furthermore, 18 patients were scanned with both the new camera and a conventional-SPECT camera. Results: The new camera had a count sensitivity that was 10 times higher than that of the conventional camera and a compensated spatial resolution that was moderately better. Dual-radionuclide studies using a phantom show the further potential of the new camera for a 2-tracer simultaneous acquisition. Two-minute clinical studies with the new camera and 11-min studies with the conventional camera qualitatively showed good-to-excellent image quality and improved myocardial edge definition for the new camera. Conclusion: These initial performance characteristics of a new solid-state single-photon g-camera offer great promise for clinical dynamic SPECT protocols, with important implications for applications in nuclear cardiology and molecular imaging. Nucl ear medicine has evolved as a clinical and research discipline for the noninvasive assessment of physiologic and molecular function in normal and diseased tissues. Principally performed with nanomolar quantities of administered radiopharmaceuticals and an external scintillation camera, nuclear medicine imaging uses 2 types of modalities: singlephoton imaging (including planar imaging and SPECT) and PET, with the former comprising nearly three fourths of all clinical procedures. With SPECT, myocardial perfusion studies predominate; these studies were performed in approximately 7,000,000 patients in the United States in 2004 and provided images of relative myocardial perfusion at rest and under stress. By assessing the extent of ischemic and infarcted myocardium, SPECT provides noninvasive information that has become central in clinical decision making, determining the need for invasive cardiac catheterization and myocardial revascularization in many patients (1,2).SPECT is typically performed using an Anger scintillation camera, named after its inventor, Hal Anger (3). Most myocardial SPECT is performed with 2 scintillation cameras oriented at 90°and mounted on a gantry that rotates around the patient. Typically, each scintillation camera is equipped with parallel-hole high-resolution collimators. Since collimation is necessary to acquire the projection views, only 0.02% of the photons emitted from the heart are collected. As a result, acquisition times of 10-20 min are required for myocardial SPECT studies. Although new detector technologies using solid-state materials have been explored (...
Key Points Immunoassays used to diagnose heparin-induced thrombocytopenia vary substantially with regard to the specific test characteristics. High sensitivity (>95%) in combination with high specificity (>90%) was found in only 5 tests.
BackgroundThrombin generation (TG) assays evaluate the balance between pro‐ and anticoagulant forces, to better assess bleeding and thrombotic risks. Although TG readouts obtained with the calibrated automated TG have been investigated in multiple clinical conditions, TG still needs standardization and clinical validation. The automated TG instrument ST Genesia® (STG, Stago, Asnières‐sur‐Seine, France) provides a normalization of TG parameters based on a reference plasma aiming to reduce the interlaboratory variability and the variability between different measurement runs.ObjectivesTo evaluate STG in a group of healthy adults.MethodsReference intervals in healthy adults and variability of the new standardized reagents for bleeding (BleedScreen) and thrombophilic (ThromboScreen) conditions were determined using STG.Results TG was measured in platelet‐free plasma (PFP) samples of 123 healthy adults. Reference intervals were determined for TG parameters. Intra‐ and interassay coefficients of variation were calculated on quality controls and PFP samples from healthy adults. Oral contraception (OC) possibly influenced TG parameters, resulting in a higher median and a broader reference interval for peak height and endogenous thrombin potential (ETP) in women aged 20 to 49 years than in all other sex and age categories. Therefore, we propose the following reference interval categories: men, women aged <50 years not using OC, women aged <50 years using OC, and women aged ≥50 years. Normalization was effective to reduce the interassay variability of quality controls for ETP (BleedScreen assay), and peak height and ETP (ThromboScreen assay without thrombomodulin), but had little impact on PFP sample variability.Conclusion STG appears suitable for accurate measurement of TG in healthy adults.
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