Journal of nuclear medicine : official publication, Society of Nuclear Medicine
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Randomized Controlled Trial Comparative Study Clinical Trial
Longer occupancy of opioid receptors by nalmefene compared to naloxone as measured in vivo by a dual-detector system.
Surgical procedures usually involve the administration of narcotic drugs as anesthetics or adjuvants. To reverse the effects of anesthesia, opioid antagonists such as naloxone are commonly used. Due to its short lasting effects, patients receiving naloxone must be monitored carefully. Nalmefene, a pure opiate antagonist with a longer duration of action than naloxone, has shown promise in the reversal of opioid anesthesia. ⋯ These findings suggest that the prolonged effects of nalmefene are related to the slow dissociation of nalmefene from opioid receptors, which are not reflected in the plasma curve. This longer blockade of opioid receptors by nalmefene represents an advantage in the clinical management of postsurgical reversal of narcotic anesthesia and opioid side effects as well as the reversal of opioid overdose.
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Quantitative assessment of atherosclerotic or atherothrombotic disease during its natural history and following therapeutic interventions is important for understanding the progression and stabilization of the disease and for selecting appropriate medical or surgical interventions. A number of invasive and noninvasive imaging techniques are available to detect and display different characteristics of vascular lesions of clinical and/or research interest. ⋯ Magnetic resonance angiography, being noninvasive, may replace conventional angiography for anatomical imaging of the vasculature. Ultrafast electron beam CT measures the calcium content in the atherosclerotic lesions. Intravascular ultrasound is the only technique that appears to be clinically useful in imaging the unstable, vulnerable plaques in coronary arteries. Magnetic resonance imaging techniques may be able to image vulnerable plaques and characterize plaques in terms of lipid and fibrous content and identify the presence of thrombus associated with the plaques. In regard to the nuclear scientigraphic imaging techniques, radiolabeled lipoproteins, platelets and immunoglobulins have shown some clinical potential as imaging agents, but due to poor target-to-background and target-to-blood ratios these agents are not ideal for imaging coronary or even carotid lesions. Technetium-99m-labeled peptides and monoclonal antibody fragments that clear from circulation rapidly and bind specifically to different components of the atherosclerotic lesion showed significant potential in animal models and in limited clinical studies. FRE Peptides capable of binding to GPIIb/IIIA receptors on activated platelets appear to offer significant diagnostic potential for imaging intra-arterial thrombus. Positron emission tomography with metabolic tracers like [18F]-fluorodeoxyglucose (FDG) also appears to offer new opportunities for noninvasive imaging of atherosclerosis and atherothrombosis.
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We propose a new method to quantify regional cerebral blood flow (rCBF) with continuous infusion of 99mTc-ethyl cysteinate dimer (ECD) and dynamic SPECT. ⋯ The proposed method with one-point arterial sampling is a simple, clinically feasible tool for quantitative measurement of rCBF with 99mTc-ECD.