Journal of nuclear medicine : official publication, Society of Nuclear Medicine
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Recent studies have clarified that hemodynamically compromised patients are at high risk for subsequent stroke. The acetazolamide test is widely used to detect the patients with hemodynamic compromise due to occlusive carotid artery disease. Previous studies have suggested that patients with impaired reactivity to acetazolamide had an increased oxygen extraction fraction (OEF) on PET. However, the underlying pathophysiology has not been defined in patients with reduced blood flow and preserved reactivity to acetazolamide due to carotid occlusive diseases regardless of a normal appearance on MRI. This study aimed to clarify hemodynamic and metabolic parameters in such patients, using (15)O gas and (11)C-flumazenil (FMZ) PET. ⋯ Our results strongly suggest that a reduced CBF and a normal CVR characterize oxygen hypometabolism probably due to ischemia-related neuronal loss-namely, incomplete infarction. Such an ischemic lesion is not hemodynamically compromised and is at very low risk for a subsequent ischemic stroke even if the patient is medically treated.
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Comparative Study
Imaging characteristics of a 3-dimensional GSO whole-body PET camera.
A whole-body 3-dimensional PET scanner using gadolinium oxyorthosilicate (GSO) crystals has been designed to achieve high sensitivity and reduced patient scanning time. This scanner has a diameter of 82.0 cm and an axial field of view of 18 cm without interplane septa. The detector comprises of 4 x 6 x 20 mm(3) GSO crystals coupled via an optically continuous light guide to an array of 420 photomultiplier tubes (39-mm diameter) in a hexagonal arrangement. The patient port diameter is 56 cm, and 2.86-cm (1.125 in.) thick lead shielding is used to fill in the region up to the detector ring. ⋯ This whole-body scanner represents a new generation of 3D, high-sensitivity, and high-performance PET cameras capable of producing high-quality images in <30 min for a full patient scan. The use of a pixelated GSO Anger-logic detector leads to a high-sensitivity scanner design with good counting rate capability due to the reduced light spread in the detector and fast decay time of GSO. The light collection over the detector is fairly uniform, leading to a good energy resolution and, thus, reduced scatter in the collected data due to a tight energy gate.
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Practice Guideline Guideline
USP general chapter <797> pharmaceutical compounding-sterile preparations.
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Clinical Trial
Preoperative assessment of postoperative remnant liver function using hepatobiliary scintigraphy.
Hepatic resection is the therapy of choice for malignant and symptomatic benign hepatobiliary tumors. The concept of remnant liver volume (RLV) has been introduced and can be assessed with CT. However, inhomogeneous liver function distribution and a lack of correlation between morphologic hypertrophy and functional recovery fuelled the enthusiasm for functional imaging. The aim of the present study was to assess liver function reserve (LFR) and remnant liver function (RLF) before and after major liver surgery with hepatobiliary scintigraphy (HBS) and to compare scintigraphic results with volumetric CT data and indocyanine-green (ICG) clearance test results. Furthermore, HBS was used to assess functional recovery of liver function, and results were compared with volumetric data. ⋯ HBS offers a unique combination of functional liver uptake and excretion with the ability to assess the preoperative LFR and to estimate the RLF preoperatively. Determination of the RLF instead of the RLV might clarify some of the discrepancies observed in the literature between RLV and clinical outcome in patients with an inhomogeneous liver function. Finally, liver function regeneration can be monitored using HBS.