Investigative radiology
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Investigative radiology · Jun 2010
Dual source dual-energy computed tomography of acute myocardial infarction: correlation with histopathologic findings in a canine model.
To evaluate the feasibility and value of dual-energy computed tomography myocardial iodine maps in the diagnosis of acute myocardial infarction. ⋯ Myocardial single- and dual-energy CT imaging shows high per-segment sensitivity and moderate specificity for detecting acute myocardial infarction in a canine model with histopathology as the standard of reference.
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New generation Dual Source computed tomography (CT) scanners offer different x-ray spectra for Dual Energy imaging. Yet, an objective, manufacturer independent verification of the dose required for the different spectral combinations is lacking. The aim of this study was to assess dose and image noise of 2 different Dual Energy CT settings with reference to a standard chest scan and to compare image noise and contrast to noise ratios (CNR). Also, exact effective dose length products (E/DLP) conversion factors were to be established based on the objectively measured dose. ⋯ Dual Energy CT is feasible without additional dose. There is no significant difference in image noise, while CNR can be doubled with optimized dual energy CT reconstructions. A restriction in collimation is required for dose-neutrality at 140/80 kVp, whereas this is not necessary at 140 Sn/100 kVp. Thus, CT can be performed routinely in Dual Energy mode without additional dose or compromises in image quality.
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Investigative radiology · May 2010
Comparative StudyDiffusion tensor imaging (DTI) of the kidney at 3 tesla-feasibility, protocol evaluation and comparison to 1.5 Tesla.
The purpose of this study was to evaluate the feasibility of diffusion tensor imaging of the kidney at a field strength of 3T. We assessed fractional anisotropy (FA) and apparent diffusion coefficients (ADC) of various acquisition protocols and determined the reproducibility of these measurements. FA, ADC, signal-to-noise ratios (SNR), and contrast-to-noise ratios (CNR) were compared with those acquired at 1.5T. ⋯ Diffusion tensor imaging of the kidney at 3T is feasible and yields significantly higher SNR and CNR. FA and ADCs do not significantly differ from 1.5T. Number of b-values influences ADC-values. Acquisitions in 12 directions provide lower cortical FA-values. We recommend a respiratory-triggered protocol because of improved image quality and reproducibility.
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Investigative radiology · May 2010
Intraindividual in vivo comparison of gadolinium contrast agents for pharmacokinetic analysis using dynamic contrast enhanced magnetic resonance imaging.
To compare the intraindividual differences of dynamic signal characteristics for 3 gadolinium chelates (gadopentetate dimeglumine [Gd-DTPA], gadodiamide [Gd-DTPA-BMA], and gadobenate dimeglumine [Gd-BOPTA]) using dynamic contrast enhanced magnetic resonance (MR) imaging (DCE-MRI) with a preclinical beagle model at 7 Tesla. ⋯ Gd chelate containing MR contrast agents can be used at 7T for DCEMRI. Gd-BOPTA demonstrates stronger signal enhancement than standard Gd chelates, in concordance with the results of studies at lower fields. The observed enhancement characteristics for the 3 contrast agents demonstrate that the pharmacokinetic parameter kep is more robust in various models using DCE-MRI than the other pharmacokinetic parameters. This information is important relative to multisite clinical trials and long-term clinical studies that often use several different contrast agents and different models.
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Investigative radiology · Apr 2010
ReviewReactive oxygen species and the pathogenesis of radiocontrast-induced nephropathy.
Experimental findings in vitro and in vivo illustrate enhanced hypoxia and the formation of reactive oxygen species (ROS) within the kidney following the administration of iodinated contrast media, which may play a role in the development of contrast media-induced nephropathy. Clinical studies indeed support this possibility, suggesting a protective effect of ROS scavenging or reduced ROS formation with the administration of N-acetyl cysteine and bicarbonate infusion, respectively. ⋯ Generated during contrast-induced renal parenchymal hypoxia, ROS may exert direct tubular and vascular endothelial injury and might further intensify renal parenchymal hypoxia by virtue of endothelial dysfunction and dysregulation of tubular transport. Preventive strategies conceivably should include inhibition of ROS generation or ROS scavenging.