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Sökning: WFRF:(Ahlström Håkan) > (2005-2009)

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1.
  • Eriksson, Rolf, 1979- (författare)
  • The Utility of Manganese for Magnetic Resonance Imaging of Transient Myocardial Ischemia
  • 2005
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • In order to improve the diagnosis of coronary artery disease, better methods for detection of myocardial perfusion defects would be useful. One of the methods used for myocardial perfusion evaluation today is magnetic resonance imaging. This method could be improved if a contrast agent that induced long-lasting contrast enhancement in the myocardium could be developed. The paramagnetic manganese(II) ion has promising properties for meeting this need, since it enters cardiomyocytes through voltage-gated calcium channels and remains inside the cells for a long time after an intravenous injection. If these properties can be utilized, manganese-enhanced MRI has potential for detecting transient periods of ischemia in a manner similar to the conventional SPECT stress test.To investigate the contrast-enhancing properties of the manganese(II) ion, a series of experiments was performed in pigs, using a manganese salt (MnCl2) and two manganese-based chelates (MnDPDP and MnHPTA) and measuring the longitudinal relaxation rates before and after contrast agent administration. This was done in normal pig myocardium at rest and during dobutamine-induced stress with several different doses of contrast agent, and in a model for coronary artery stenosis using MnCl2 administered during dobutamine stress to determine whether transient ischemia could be detected with this contrast agent.The results of these experiments showed that of the three contrast agents, MnCl2 induces the greatest increase in ΔR1, followed by MnHPTA. Using MnCl2 it was possible to produce images on which transient myocardial ischemia was visible, but only during the first 30 minutes after contrast agent injection.The stenosis model is still far from the clinical situation and several complications, including the potential toxicity of the manganese(II) ion, remain to be overcome. However, the results from this model are promising for the future development of manganese- enhanced magnetic resonance imaging of transient myocardial ischemia.
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2.
  • Hedström, Erik, et al. (författare)
  • Importance of perfusion in myocardial viability studies using delayed contrast-enhanced magnetic resonance imaging
  • 2006
  • Ingår i: Journal of Magnetic Resonance Imaging. - : Wiley. - 1053-1807 .- 1522-2586. ; 24:1, s. 77-83
  • Tidskriftsartikel (refereegranskat)abstract
    • PURPOSE: To investigate whether an extracellular gadolinium-(Gd)-based contrast agent (CA) enters nonperfused myocardium during acute coronary occlusion, and whether nonperfused myocardium presents as hyperintense in delayed contrast-enhanced (DE) MR images in the absence of CA in that region. MATERIALS AND METHODS: The left anterior descending coronary artery (LAD) was occluded for 200 minutes in six pigs. The longitudinal relaxation rate (R(1)) in blood, perfused myocardium, and nonperfused myocardium was repeatedly measured using a Look-Locker sequence before and during the first hour after administration of Gd-DTPA-BMA. RESULTS: While blood and perfused myocardium showed a major increase in R(1) after CA administration, nonperfused myocardium did not. R(1) in nonperfused myocardium was significantly lower than in blood and perfused myocardium during the first hour after CA administration. When the signal from perfused myocardium was nulled, demarcation of the hyperintense nonperfused myocardium was achieved in all of the study animals. CONCLUSION: Gd-DTPA-BMA does not enter ischemic myocardium within one hour after administration during acute coronary occlusion. The ischemic region with complete absence of CA still appears bright when the signal from perfused myocardium is nulled using inversion-recovery DE-MRI. This finding is important for understanding the basic pathophysiology of inversion-recovery viability imaging, as well as for imaging of acute coronary syndromes.
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3.
  • Briley-Saebo, Karen C., et al. (författare)
  • Clearance of iron oxide particles in rat liver : effect of hydrated particle size and coating material on liver metabolism
  • 2006
  • Ingår i: Investigative Radiology. - : Ovid Technologies (Wolters Kluwer Health). - 0020-9996 .- 1536-0210. ; 41:7, s. 560-571
  • Tidskriftsartikel (refereegranskat)abstract
    • OBJECTIVES: We sought to evaluate the effect of the particle size and coating material of various iron oxide preparations on the rate of rat liver clearance. MATERIALS AND METHODS: The following iron oxide formulations were used in this study: dextran-coated ferumoxide (size = 97 nm) and ferumoxtran-10 (size = 21 nm), carboxydextran-coated SHU555A (size = 69 nm) and fractionated SHU555A (size = 12 nm), and oxidized-starch coated materials either unformulated NC100150 (size = 15 nm) or formulated NC100150 injection (size = 12 nm). All formulations were administered to 165 rats at 2 dose levels. Quantitative liver R2* values were obtained during a 63-day time period. The concentration of iron oxide particles in the liver was determined by relaxometry, and these values were used to calculate the particle half-lives in the liver. RESULTS: After the administration of a high dose of iron oxide, the half-life of iron oxide particles in rat liver was 8 days for dextran-coated materials, 10 days for carboxydextran materials, 14 days for unformulated oxidized-starch, and 29 days for formulated oxidized-starch. CONCLUSIONS: The results of the study indicate that materials with similar coating but different sizes exhibited similar rates of liver clearance. It was, therefore, concluded that the coating material significantly influences the rate of iron oxide clearance in rat liver.
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4.
  • Ebeling Barbier, Charlotte, et al. (författare)
  • Clinically unrecognized myocardial infarction detected at MR imaging may not be associated with atherosclerosis
  • 2007
  • Ingår i: Radiology. - : Radiological Society of North America (RSNA). - 0033-8419 .- 1527-1315. ; 245:1, s. 103-110
  • Tidskriftsartikel (refereegranskat)abstract
    • Purpose: To prospectively investigate whether there is support for the hypothesis that clinically unrecognized myocardial infarctions (UMIs) detected at magnetic resonance (MR) imaging have an atherosclerotic pathogenesis similar to that of recognized myocardial infarctions (RMIs). Materials and Methods: After ethics committee approval and informed consent were obtained, gadolinium-enhanced whole-body MR angiography and late-enhancement MR imaging were performed in 248 randomly chosen 70-year-old subjects (123 women, 125 men). Imaging included the aorta and the carotid, renal, and lower limb arteries to the ankle, but not the coronary arteries. Subjects with myocardial infarction (MI) scars at late-enhancement MR imaging were classified as having RMI (n = 11) (those with a diagnosis of MI at the hospital) or UMI (n = 49) (those without a diagnosis of MI at the hospital). The presence of 50% or higher luminal narrowing in any vessel at whole-body MR angiography was considered to represent significant atherosclerosis. Intima-media thickness of the common carotid artery was measured with ultrasonography. C-reactive protein level was measured, and coronary heart disease risk was estimated. Observers were blinded to any previous results. The chi(2) test analysis of variance, and Bonferroni correction were used for statistical analyses. Results: None of the measured parameters differed significantly between the group without MI scars and the UMI group, but parameters were significantly increased in the RMI group (P < .05) compared with those in the group without MI scars. Forty-two of 49 UMIs and nine of 11 RMIs were located within inferolateral segments of the left ventricle. Conclusion: MR imaging-detected UMIs might have a different pathogenesis from that of RMIs or may have the same pathogenesis but may manifest at an earlier stage.
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5.
  • Ebeling Barbier, Charlotte, et al. (författare)
  • Myocardial scars more frequent than expected - Magnetic resonance imaging detects potential risk group
  • 2006
  • Ingår i: Journal of the American College of Cardiology. - : Elsevier BV. - 0735-1097 .- 1558-3597. ; 48:4, s. 765-771
  • Tidskriftsartikel (refereegranskat)abstract
    • Objectives: The aim of this study was to investigate the prevalence of clinically recognized myocardial infarctions (RMIs) and unrecognized myocardial infarctions (UMIs) in 70-year-old subjects, assessed with magnetic resonance imaging (MRI), and to relate the findings to cardiac function and morbidity. Background: Late enhancement MRI identifies myocardial scars and thereby has the potential to detect UMI. Methods: Cardiac MRI was performed on 259 randomly chosen 70-year-old subjects. Late enhancement and cine sequences were acquired, and the ejection fraction and left ventricular (LV) mass were calculated. Late enhancement involving the subendocardial layer was considered to represent myocardial infarction (MI) scars, and their volumes were calculated. Information on cardiac morbidity and risk factors was collected from medical records and from a health examination. Subjects with MI scars, with or without a hospital diagnosis of MI were classified as RMI or UMI, respectively. Results: The images from 248 subjects (123 women, 125 men) were assessable. Myocardial infarction scars were found in 60 subjects (24.2%), in 49 of whom (19.8%) they were UMIs. The volumes of the UMIs were significantly smaller than those of the RMIs. There was an increased frequency of chest pain symptoms among the subjects with UMI or RMI compared with those without MI scars. Ejection fraction was significantly lower and LV mass significantly larger in the subjects with UMI or RMI than in those without MI scars. Conclusions: Unrecognized MI detected with MRI was more frequent than expected in 70-year-old subjects. The subjects displaying these UMIs may represent a previously unknown potential risk group for future cardiovascular events.
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6.
  • Ebeling Barbier, Charlotte, 1969- (författare)
  • Myocardial Scars on MRI : Their Prevalence and Possible Impact
  • 2007
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Myocardial infarction (MI) causes high morbidity and mortality worldwide and for effective prevention and treatment MIs have to be adequately detected.The existence of clinically unrecognized MIs (UMIs) has been known for the past hundred years, but an ultimate tool for their detection has not yet been found. Using persistent Q waves on electrocardiography as a sign of MI, it has been estimated that UMIs constitute at least ¼ of all MIs and have mortality rates similar to those of recognized MIs (RMIs). These estimates are misleading, however, since persistent Q waves do not necessarily represent MIs.The late enhancement technique in magnetic resonance imaging (LE MRI) has been developed over the past decade and accurately determines myocardial viability. The aim of this research was to investigate the prevalence and impact of UMI and RMI in a population-based sample of 70-year-olds, assessed with MRI.Cardiac function and viability were examined with MRI in 259 randomly selected 70-year-old subjects (127 women, 132 men) participating in a larger population-based study (PIVUS). Information on other parameters of cardiovascular disease was obtained and related to the findings.Three methods for segmentation of the left ventricular mass were used in the first 100 subjects; these differed in accuracy and led to differences in systolic function values. In the subsequent 159 examinations one of the segmentation methods was used.The viability images were assessable in 248 subjects (123 women, 125 men). Among these, the prevalence of UMI, 19.8%, definitely exceeded the expectations and UMIs constituted 4/5 of all MIs. The prevalence of RMI was 4.4%. MRI-detected UMIs differed from RMIs in several respects; they were smaller, frequently located inferolaterally, did not appear to be associated with atherosclerosis, and displayed increased collagen turnover. The pathogenesis of these UMIs remains to be investigated, but our observations suggest that they are caused by ischemia. Subjects with UMI showed increased cardiac morbidity, a decreased ejection fraction and an increased left ventricular mass, indicating an increased cardiovascular risk.It is thus important to detect these UMIs, and this is adequately achieved by LE MRI. However, to decide upon prevention and treatment of these UMIs we need to know more about their pathogenesis and prognosis.
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7.
  • Ebeling Barbier, Charlotte, et al. (författare)
  • The exactness of left ventricular segmentation in cine magnetic resonance imaging and its impact on systolic function values
  • 2007
  • Ingår i: Acta Radiologica. - : SAGE Publications. - 0284-1851 .- 1600-0455. ; 48:3, s. 285-291
  • Tidskriftsartikel (refereegranskat)abstract
    • Purpose: To evaluate the impact of exactness of the segmentation of the left ventricle (LV), using cine magnetic resonance imaging (MRI). Material and methods: Steady-state free-precession cine MRI was performed on 100 randomly selected subjects. Myocardial borders were outlined on short-axis images using three methods: method 1 was computer assisted, excluding papillary muscles from the left ventricular mass (LVM); method 2 was similar but included papillary muscles; and method 3 was manually traced including papillary muscles. LV end-systolic (ES) and end-diastolic (ED) masses and volumes, ejection fraction (EF), stroke volume (SV), and cardiac output (CO) were calculated from these measurements. The difference between the ES and ED LVM was used to estimate the exactness of the methods. Results: Method 3 was the most exact, and method 1 was the least exact. The three methods generated differing EF, SV, and CO measurements. With an ES-ED LVM difference exceeding 20 g, the mean SV measurement error was 8.83.6 ml. Conclusion: Manual tracing proved more exact than computer-assisted quantification. Exactness had an impact on EF, SV, and CO measurements, and the ES-ED LVM difference can be used to identify assessments that would benefit from more exact segmentation.
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8.
  • Edwards, David, et al. (författare)
  • 99mTc-NC100668, an agent for imaging venous thromboembolism : The effect of anticoagulant or thrombolytic therapy on the uptake and retention of radioactivity in blood clots in vivo
  • 2007
  • Ingår i: Nuclear medicine communications. - : Ovid Technologies (Wolters Kluwer Health). - 0143-3636 .- 1473-5628. ; 28:1, s. 55-62
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND: The purpose of this study was to evaluate the uptake of Tc-NC100668 into blood clots and elucidate the potential for medications commonly used to treat thromboembolism to interfere with the uptake and retention of Tc-NC100668. METHODS: Tc-NC100668 in vivo uptake and retention in a range of blood clot of various ages (up to 4 h old) and in the presence of anticoagulants or thrombolytic therapies was measured in a rat model of deep vein thrombosis. RESULTS: Tc-NC100668 was rapidly absorbed into and retained by blood clots and was not significantly affected by the presence of unfractionated or low molecular weight heparin or thrombin inhibitor. Tissue plasminogen activator reduced the uptake of Tc-NC100668 into blood clot by a factor of 3 when adjusted to allow for changes in the weight of the blood clot. CONCLUSIONS: This study has demonstrated that the uptake and retention of Tc-NC100668 into blood clots in the rat model of deep vein thrombosis is rapid and maintained over at least a 4 h post-injection period. It has been shown that Tc-NC100668 is retained in blood clots even in the presence of therapeutic doses of those anticoagulant and thrombolytic therapies typically used to treat pulmonary embolism and venous thrombosis.
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9.
  • Edwards, David, 1971- (författare)
  • Pre-Clinical Evaluation of a Novel Radiotracer for the Diagnosis of DVT and Pulmonary Embolism.
  • 2006
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Deep vein thrombosis (DVT) and pulmonary embolism (PE) are different aspects of a single condition, venous thrombo-embolic disease (VTE), a major cause of morbidity and mortality in the western world. Rapid diagnosis is critical, as timely medical intervention can have a substantial beneficial effect on the mortality rate. Irrespective of its presentation, VTE is a difficult disease to diagnose. Pathologies unrelated to VTE can give rise to a clinical presentation similar to DVT or PE, resulting in a false positive diagnosis. This raises the risk of a patient being treated inappropriately. Therefore, there is a need for an agent that has high specificity and sensitivity for the detection of active blood clots, which are amenable to treatment by anticoagulant and/or thrombolytic therapy. This work describes the pre-clinical efficacy studies performed on one such agent, 99mTc-NC100668. 99mTc-NC100668 is a substrate for factor XIIIa and as a potential physiological, rather than anatomical, marker of VTE it is hoped it will not give rise to the false negative and positive diagnoses that are inherent in the currently available diagnostic techniques, such as the ventilation perfusion (V/Q) scan, multidetector computer tomography or ultrasound. It is reported in this work that 99mTc-NC100668 uptake and retention in blood clot was rapid and maintained over at least a 4 hour period in a rat model of DVT. Anticoagulant and thrombolytic therapies commonly used to treat thrombosis did not seriously impair the ability of 99mTc-NC100668 to detect thrombi. No significant tissue retention, which could interfere with the ability to image thrombi in vivo, was observed. Biodistribution and plasma clot uptake studies showed that 99mTc complex of gly-NC100194, the major metabolite of 99mTc-NC100668, would be unlikely to affect adversely the clinical utility of the test substance. The in vitro uptake of 99mTc-NC100668 into forming plasma clots indicated that retention into human blood clots would be comparable with the observations made in the rat preclinical models. The uptake of 99mTc-NC100668 in vitro and in vivo was much greater than could be accounted for by physical entrapment into the forming blood clots. The reduced uptake of a biologically inactive analogue of 99mTc-NC100668 both in vitro and in vivo indicated that the blood clot uptake and retention of 99mTc-NC100668 was mediated by factor XIIIa. In conclusion, 99mTc-NC100668 might be useful in the detection of thrombo embolism.
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10.
  • Edwards, David, et al. (författare)
  • Tc-99m-NC100668, a new tracer for imaging venous thromboemboli : pre-clinical biodistribution and incorporation into plasma clots in vivo and in vitro
  • 2006
  • Ingår i: European Journal of Nuclear Medicine and Molecular Imaging. - : Springer Science and Business Media LLC. - 1619-7070 .- 1619-7089. ; 33:11, s. 1258-1265
  • Tidskriftsartikel (refereegranskat)abstract
    • Purpose: Tc-99m-NC100668 is a new radiotracer being developed to aid the diagnosis of thromboembolism. The structure of NC100668 is similar to a region of human alpha(2)-antiplasmin, which is a substrate for factor XIIIa (FXIIIa). The purpose of this study was to confirm the uptake of Tc-99m-NC100668 into forming plasma clot and to establish the biodistribution of Tc-99m-NC100668 in Wistar rats. Methods: The in vitro plasma clot uptake of Tc-99m-NC100668 and other compounds with known affinities to FXIIIa was measured using a plasma clot assay. The biodistribution and blood clot uptake of radioactivity of Tc-99m-NC100668 in normal Wistar rats and those bearing experimentally induced deep vein thrombi were investigated. Results: The in vitro uptake of Tc-99m-NC100668 was greater than that for [C-14] dansyl cadaverine, a known substrate of FXIIIa in the plasma clot assay. The biodistribution of Tc-99m-NC100668 in male and female Wistar rats up to 24 h p.i. showed that radioactivity was rapidly excreted, predominantly into the urine, with very little background tissue retention. In vivo the uptake and retention of Tc-99m-NC100668 into the blood clot was greater than could be accounted for by non-specific accumulation of the radiotracer within the blood clot. Conclusion: Tc-99m-NC100668 was retained by plasma clots in vitro and blood clots in vivo. No significant tissue retention which could interfere with the ability to image thrombi in vivo was observed. This evidence suggests that Tc-99m-NC100668 might be useful in the detection of thromboembolism.
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11.
  • Edwards, David, et al. (författare)
  • The biodistribution of NC100668 and the effect of excess NC100668 on the biodistribution and kidney retention of Tc-99m-NC100668 in the rat
  • 2007
  • Ingår i: Nuclear Medicine and Biology. - : Elsevier BV. - 0969-8051 .- 1872-9614. ; 34:3, s. 315-323
  • Tidskriftsartikel (refereegranskat)abstract
    • INTRODUCTION: (99m)Tc-NC100668 is being developed to aid the diagnosis of thromboemboli. The purpose of this study was to investigate if the presence of excess NC100668 interferes with the biodistribution and blood clot uptake of (99m)Tc-NC100668. The secondary aim was to investigate the causes underlying the kidney retention of (99m)Tc-NC100668. METHODS: The uptake of a (14)C-labelled analogue of NC100668, as well as (99m)Tc-NC100668, into plasma (in vitro) and blood (in vivo) clots was determined. The biodistribution of (99m)Tc-NC100668 at a range of NC100668 doses was studied in normal Wistar rats and those bearing experimentally induced deep venous thrombosis. The biodistribution of a negative control peptide and (99m)Tc-NC100668 plus L-lysine was studied in healthy male Wistar rats. RESULTS: The biodistribution as well as plasma clot uptake of [Asn-U-(14)C]NC100668 and (99m)Tc-NC100668 was similar. Apart from some reduction in kidney retention, the biodistribution and uptake of radioactivity into the blood clot were not significantly affected by the presence of up to 1000 times the clinical dose of NC100668. Kidney retention of radioactivity could be more effectively reduced by coadministration of 889 microg/kg NC100668 than 450 mg/kg L-lysine. A negative control peptide with no affinity for FXIIIa demonstrated very little kidney retention. CONCLUSIONS: The biodistribution and blood clot uptake of (99m)Tc-NC100668 and [Asn-U-(14)C]NC100668 are similar. With the exception of the kidneys, (99m)Tc-NC100668 biodistribution and blood clot uptake are unaffected by the presence of unlabelled NC100668. The kidney retention of radioactivity is probably due to transglutaminase activity and, to a lesser extent, nonspecific charge-mediated endocytosis.
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12.
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13.
  • Edwards, David, et al. (författare)
  • The in vivo and in vitro metabolic profile of 99mTc-NC100668, a new tracer for imaging venous thromboembolism : identification and biodistribution of the principal radiolabeled metabolite
  • 2006
  • Ingår i: Drug Metabolism And Disposition. - : American Society for Pharmacology & Experimental Therapeutics (ASPET). - 0090-9556 .- 1521-009X. ; 34:7, s. 1128-1135
  • Tidskriftsartikel (refereegranskat)abstract
    • (99m)Tc-NC100668 [Acetyl-Asn-Gln-Glu-Gln-Val-Ser-Pro-Tyr(3-iodo)-Thr-Leu-Leu-Lys-Gly-NC100194] is a radiopharmaceutical imaging agent being developed to aid the diagnosis of thromboembolism. The stability profile of (99m)Tc-NC100668 was investigated by high-performance liquid chromatography (HPLC) after in vitro exposure to blood and plasma obtained from rat and human, as well as to urine and bile obtained from rat. The metabolic profile of (99m)Tc-NC100668 exposed to human and rat hepatic S9 (a liver homogenate-rich cytochrome P450) was also studied. The profile of (99m)Tc-labeled species in plasma, urine, and bile was investigated following i.v. administration of (99m)Tc-NC100668 to rat. The major species observed in vitro and in vivo consisted of the (99m)Tc-chelator (NC100194) [N,N-Bis(N-(1,1-dimethyl-2-(hydroxylimino-)propyl)aminoethyl)aminoethylamine] attached to the C-terminal amino acid residue and referred to as (99m)Tc-complex of Gly-NC100194. The identity of the major metabolite was confirmed by cochromatography with an authentic standard and the genuine metabolite using a second HPLC method. The minor metabolites were sodium pertechnetate ((99m)Tc) and (99m)Tc-NC100194. In addition, a small number of other species were transiently observed in vitro; they were not investigated further. The biodistribution of the major metabolite was studied in male Wistar rats. The affinity of the major metabolite toward plasma clot was established using a plasma clot-forming assay. A minor uptake of (99m)Tc-complex of Gly-NC100194 in the plasma clot and a rapid removal from the body were noted. In conclusion, the metabolites of (99m)Tc-NC100668 are not anticipated to have a negative impact on the ability of the test substance to image blood clots.
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14.
  • Eggers, Kai M., 1962-, et al. (författare)
  • Prevalence and pathophysiological mechanisms of elevated cardiac troponin 1 levels in a population-based sample of elderly subjects
  • 2008
  • Ingår i: European Heart Journal. - : Oxford University Press (OUP). - 0195-668X .- 1522-9645. ; 29:18, s. 2252-2258
  • Tidskriftsartikel (refereegranskat)abstract
    • AIMS: To evaluate the prevalence of cardiac troponin I (cTnI) elevation in an elderly community population and the association of cTnI levels with cardiovascular risk factors, vascular inflammation, atherosclerosis, cardiac performance, and areas indicative of infarcted myocardium identified by cardiac magnetic resonance imaging. METHODS AND RESULTS: cTnI elevation defined as cTnI levels >0.01 microg/L (Access AccuTnI, Beckman Coulter) was found in 21.8% of the study participants (n = 1005). cTnI > 0.01 microg/L was associated with cardiovascular high-risk features, the burden of atherosclerosis in the carotid arteries, left-ventricular mass, and impaired left-ventricular systolic function. No associations were found between cTnI and inflammatory activity, diastolic dysfunction, or myocardial scars. Male gender (OR 1.6; 95% CI 1.1-2.4), ischaemic ECG changes (OR 1.7; 95% CI 1.1-2.7), and NT-pro-brain natriuretic peptide levels (OR 1.4; 95% CI 1.1-1.7) independently predicted cTnI > 0.01 microg/L. cTnI > 0.01 microg/L correlated also to an increased cardiovascular risk according to the Framingham risk score. CONCLUSION: cTnI > 0.01 microg/L is relatively common in elderly subjects and is associated with cardiovascular high-risk features and impaired cardiac performance. Cardiac troponin determined by a highly sensitive assay might thus serve as an instrument for the identification of subjects at high cardiovascular risk in general populations.
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15.
  • Eklöf, Hampus, et al. (författare)
  • A prospective comparison of duplex ultrasonography, Captopril renography, MRA and CTA in assessing renal artery stenosis
  • 2006
  • Ingår i: Acta Radiologica. - : SAGE Publications. - 0284-1851 .- 1600-0455. ; 47:8, s. 764-774
  • Tidskriftsartikel (refereegranskat)abstract
    • Purpose: To prospectively compare the diagnostic accuracy of duplex ultrasonography, captopril renography, computed tomography angiography (CTA), and 3D Gd magnetic resonance angiography (MRA) in diagnosing hemodynamically significant renal artery stenosis (RAS). Material and Methods: The standard of reference was measurement of transstenotic pressure gradient. Fifty-eight hypertensive patients with suspicion of RAS were evaluated, when possible, by all five techniques. Sensitivity and specificity to detect RAS were compared for each technique on both a patient and kidney basis. Discrepancies were evaluated separately and classified as borderline, method dependent, or operator dependent. Results: The prevalence of RAS was 77%. The sensitivity/specificity of ultrasonography, captopril renography, CTA, and MRA in detecting kidneys with RAS was 73/71%, 52/63%, 94/62%, and 93/91%, respectively. Ultrasonography had a significantly lower sensitivity than CTA and MRA (P < 0.001) but higher than captopril renography (P = 0.013). Borderline RAS was the main cause for discrepancies. Conclusion: MRA and CTA were significantly better than duplex ultrasonography and captopril renography in detecting hemodynamically significant RAS. The ultrasonography criteria for RAS based on the evaluation of renal peak systolic velocity and renal/aortic ratio are questionable. Captopril renography cannot be recommended for assessing RAS.
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16.
  • Eklöf, Hampus, et al. (författare)
  • Renal artery stenosis evaluated with magnetic resonance angiography using intraarterial pressure gradient as the standard of reference : A multireader study
  • 2005
  • Ingår i: Acta Radiologica. - : SAGE Publications. - 0284-1851 .- 1600-0455. ; 46:8, s. 802-809
  • Tidskriftsartikel (refereegranskat)abstract
    • PURPOSE: To evaluate 3D-Gd-magnetic resonance angiography (MRA) in detecting hemodynamically significant renal artery stenosis (RAS). MATERIAL AND METHODS: Thirty patients evaluated for atherosclerotic RAS by MRA and digital subtraction angiography (DSA) were retrospectively included. Standard of reference for hemodynamically significant RAS was a transstenotic gradient of 15 mmHg. DSA visualized 60 main renal arteries and 9 accessory arteries. Pressure gradient measurement (PGM) was available from 61 arteries. Three radiologists evaluated all examinations independently in a blinded fashion. RESULTS: RAS was present in 26 arteries. On MRA, each reader identified 4 of 9 accessory renal arteries, a detection rate of 44%. The three readers correctly classified 22/25/22 of the 26 vessels with a significant gradient as > or =60% RAS and 31/25/32 of the 35 with no significant gradient as < 60% RAS on MRA. Interobserver agreement was substantial. MRA image quality was adequate for RAS evaluations in all patients. ROC curves indicated that MRA is an adequate method for evaluating RAS. When screening for RAS, a 50% diameter reduction cut-off is better than 60%. RAS with 40-80% diameter reductions accounted for 65% of discrepancies. CONCLUSION: MRA is an adequate method for evaluating RAS limited mainly by poor detection rate for accessory renal arteries.
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17.
  • Eriksson, Jan W., et al. (författare)
  • Hydrochlorothiazide, but not Candesartan, aggravates insulin resistance and causes visceral and hepatic fat accumulation : the mechanisms for the diabetes preventing effect of Candesartan (MEDICA) Study
  • 2008
  • Ingår i: Hypertension. - : American Heart Association. - 0194-911X .- 1524-4563. ; 52:6, s. 1030-1037
  • Tidskriftsartikel (refereegranskat)abstract
    • Treatment with angiotensin II receptor blockers is associated with lower risk for the development of type 2 diabetes mellitus compared with thiazide diuretics. The Mechanisms for the Diabetes Preventing Effect of Candesartan Study addressed insulin action and secretion and body fat distribution after treatment with candesartan, hydrochlorothiazide, and placebo. Twenty-six nondiabetic, abdominally obese, hypertensive patients were included in a multicenter 3-way crossover trial, and 22 completers (by predefined criteria; 10 men and 12 women) were included in the analyses. They underwent 12-week treatment periods with candesartan (C; 16 to 32 mg), hydrochlorothiazide (H; 25 to 50 mg), and placebo (P), respectively, and the treatment order was randomly assigned and double blinded. Intravenous glucose tolerance tests and euglycemic hyperinsulinemic (56 mU/m(2) per minute) clamps were performed. Intrahepatic and intramyocellular and extramyocellular lipid content and subcutaneous and visceral abdominal adipose tissue were measured using proton magnetic resonance spectroscopy and MRI. Insulin sensitivity (M-value) was reduced following H versus C and P (6.07+/-2.05, 6.63+/-2.04, and 6.90+/-2.10 mg/kg of body weight per minute, mean+/-SD; P
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18.
  • Eriksson, Rolf, et al. (författare)
  • Contrast enhancement of manganese-hydroxypropyl-tetraacetic acid, an MR contrast agent with potential for detecting differences in myocardial blood flow
  • 2006
  • Ingår i: Journal of Magnetic Resonance Imaging. - : Wiley. - 1053-1807 .- 1522-2586. ; 24:4, s. 858-863
  • Tidskriftsartikel (refereegranskat)abstract
    • Purpose: To determine whether the contrast agent MnHPTA has potential for detecting differences in myocardial blood flow. Materials and Methods: R1 in the myocardium was calculated from MR signal intensity measurements in 18 pigs after intravenous injection of 5, 15, or 25 mu mol MnHPTA/kg body weight. Measurements were made in each animal after administration at rest and during dobutamine-induced stress. Results: A difference of approximately 0.1 see(-1) in the R1 increase between rest and stress still remained 31 minutes after administration of 25 mu mol MnHPTA/kg body weight. When two consecutive MnHPTA injections were performed, the second injection induced a lower R1 increase than the corresponding first injection. Conclusion: MnHPTA at a dose of 25 mu mol/kg body weight (b.w.) has the potential to detect perfusion differences in myocardium. When two consecutive injections of MnHPTA were administered, the RI change after the second injection was affected by the earlier administration. Therefore, a protocol including more than one administration is not ideal for this contrast agent.
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19.
  • Forsberg, Anders, et al. (författare)
  • Landmark-Based Software for Anatomical Measurements : A Precision Study
  • 2009
  • Ingår i: Clinical anatomy (New York, N.Y. Print). - : Wiley. - 0897-3806 .- 1098-2353. ; 22:4, s. 456-462
  • Tidskriftsartikel (refereegranskat)abstract
    • The aim of this study was to develop a software program, called Landmarker, which would aid studies of complex anatomical morphometry by simplifying the manual identification of landmarks in 3D images. We also tested its precision on routine magnetic resonance imaging (MRI) scans. To understand human biological variation, there is a need to identify morphological characteristics from the exterior and the interior of human anatomy. MRI, as opposed to other radiographic methods (mainly based on X-ray techniques), supplies good soft tissue contrast, which allows for more complex assessments than what bony landmarks can provide. Because automation of this assessment is highly demanding, one of the primary goals for the new software was to enable more rapid identification of landmark sets in 3D image data. Repeat acquisition of head MRIs having a resolution of 0.94 x 0.94 x 1.20 mm3 were performed on 10 volunteers. Intra- and interoperator, as well as interacquisition variations of manual identification of exterior, craniofacial interior, and brain landmarks were studied. The average distances between landmarks were <1.8 mm, <2.3 mm, and <2.0 mm in the intra- and interoperator, and interacquisition evaluations, respectively. This study presents new software for time efficient identification of complex craniofacial landmarks in 3D MRI. To the best of our knowledge, no evaluation of software for rapid landmark-based analysis of complex anatomies from 3D MR data has yet been presented. This software may also be useful for studies in other anatomical regions and for other types of image data.
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20.
  • Hahn, Gabriele, et al. (författare)
  • Pharmacokinetics and safety of gadobutrol-enhanced magnetic resonance imaging in pediatric patients
  • 2009
  • Ingår i: Investigative Radiology. - 0020-9996 .- 1536-0210. ; 44:12, s. 776-783
  • Tidskriftsartikel (refereegranskat)abstract
    • OBJECTIVES: This clinical study investigated the pharmacokinetics and safety of gadobutrol, a magnetic resonance (MR) imaging extracellular contrast agent, in pediatric patients aged 2 to 17 years. MATERIALS AND METHODS: In this open-label, multicenter study, patients scheduled for routine contrast-enhanced MR imaging of the brain, spine, liver or kidney, or MR angiography received a single intravenous injection of gadobutrol (0.1 mmol/kg/0.1 mL/kg). Patients were stratified by age groups (2-6, 7-11, and 12-17 years). Blood and urine samples were collected at prespecified time points and analyzed for gadolinium concentrations. Plasma data were evaluated by means of a nonlinear mixed effects model, and urine data were analyzed using descriptive statistics. In addition, the safety of gadobutrol was evaluated. RESULTS: A total of 130 patients (2-6 years, n = 45; 7-11 years, n = 39; 12-17 years, n = 46) were included in the final population pharmacokinetic analysis. Gadobutrol pharmacokinetics in children aged 2 to 17 years were adequately described by an open 2-compartment model with elimination from the central compartment. The median estimates (2.5th percentile, 97.5th percentile) of body weight-normalized total body clearance (L/h/kg) per age group were 0.10 (0.05, 0.17) for all ages, 0.13 (0.09, 0.17) in the 2 to 6 year age group, 0.10 (0.05, 0.17) in the 7 to 11 year age group and 0.09 (0.05, 0.10) in the 12 to 17 year age group. The body weight-normalized median estimates of total volume of distribution (L/kg) were 0.20 (0.12, 0.28) for all ages, 0.24 (0.20, 0.28) in the 2 to 6 year age group, 0.19 (0.14, 0.23) in the 7 to 11 year age group and 0.18 (0.092, 0.23) in the 12 to 17 year age group. Median gadolinium plasma concentrations at 20 minutes postinjection were simulated using the population pharmacokinetic model and ranged from 414 (13 kg subject) to 518 micromol/L (65 kg subject). Body weight was identified as the major covariate influencing the pharmacokinetic parameters of total body clearance and central volume of distribution. Age was not found to be an additional independent parameter. The median amount of renally excreted gadolinium was 77.0% of the administered dose within 6 hours postinjection, indicating that gadobutrol was renally excreted in this pediatric population aged 2 to 17 years. Gadobutrol was well tolerated, with drug-related adverse events of mild intensity reported for 8 (5.8%) of 138 patients. CONCLUSIONS: Observed differences in pharmacokinetics were attributed to body weight, with no additional independent effect of age. Thus, no dose adjustment from the standard dose of gadobutrol in adults based on body weight (0.1 mmol/kg) is necessary in pediatric patients aged 2 to 17 years. Gadobutrol was safe and well tolerated in the pediatric population in this study.
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21.
  • Hansen, Tomas, et al. (författare)
  • A total atherosclerotic score for whole-body MRA and its relation to traditional cardiovascular risk factors
  • 2008
  • Ingår i: European Radiology. - : Springer Science and Business Media LLC. - 0938-7994 .- 1432-1084. ; 18:6, s. 1174-1180
  • Tidskriftsartikel (refereegranskat)abstract
    • The aim of this study was to create a scoring system for whole-body magnetic resonance angiography (WBMRA) that allows estimation of atherosclerotic induced luminal narrowing, and determine whether the traditional cardiovascular (CV) risk factors included in the Framingham risk score (FRS) were related to this total atherosclerotic score (TAS) in an elderly population. A group of 306 subjects, aged 70, were recruited from the general population and underwent WBMRA in a 1.5-T scanner. Three-dimensional sequences were acquired after administration of one i.v. injection of 40 ml gadodiamide. The arterial tree was divided into five territories (carotid, aorta, renal, upper and lower leg) comprising 26 vessel segments, and assessed according to its degree of stenosis or occlusion. FRS correlated to TAS (r=0.30, P < 0.0001), as well as to the atherosclerotic score for the five individual territories. Of the parameters included in the FRS, male gender (P < 0.0001), systolic blood pressure (P=0.0002), cigarette pack-years (P=0.0008) and HDL cholesterol (P=0.008) contributed to the significance. A scoring system for WBMRA was created. The significant relation towards traditional CV risk factors indicates that the proposed scoring system could be of value for assessing atherosclerotically induced luminal narrowing.
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22.
  • Hansen, Tomas, 1970- (författare)
  • Assessment of Atherosclerosis by Whole-Body Magnetic Resonance Angiography.
  • 2007
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Atherosclerosis is a serious threat to public health and a major cause of morbidity and mortality. In this doctoral research, the feasibility of using whole-body magnetic resonance angiography (WBMRA) was studied as a principal aim both in patients and in an epidemiological setting. Secondary aims were to create a score for assessment of the degree of atherosclerosis with the use of WBMRA and to investigate the correlation between this score and various cardiovascular (CV) risk factors. WBMRA was found feasible both in atherosclerotic patients and in an elderly population from the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS). All subjects except one completed the examination without any adverse events. A large proportion (93-99%) of the vessel segments could be evaluated and the results of a smaller comparison between WBMRA and conventional invasive x-ray angiography were reasonable regarding the assessed degree of maximum stenosis or occlusion. This indicates the safety and robustness of the WBMRA method.Unsuspected significant vascular abnormalities were found in patients with atherosclerotic symptoms and significant vascular abnormalities were present in elderly subjects without any self-reported vascular disease. The prevalence rates of vascular abnormalities in the carotid, renal, and inflow and runoff arteries of the lower limbs were estimated in an elderly population. A total atherosclerotic score (TAS) reflecting the degree of luminal narrowing was created for the WBMRA method and was significantly related to Framingham risk score (FRS) and to the amount of abdominal visceral adipose tissue, interleukin-6, and leptin and was inversely significantly related to adiponectin. Studies with outcome data of the PIVUS cohort are needed for further validation of the WBMRA method and to determine whether TAS can be used as an adjunct for CV risk assessment. Meanwhile, the correlation with FRS indicates that TAS could be of value for this purpose.
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23.
  • Hansen, Tomas, et al. (författare)
  • The Prevalence and Quantification of Atherosclerosis in an Elderly Population Assessed by Whole-Body Magnetic Resonance Angiography
  • 2007
  • Ingår i: Arteriosclerosis, Thrombosis and Vascular Biology. - 1079-5642 .- 1524-4636. ; 27:3, s. 649-654
  • Tidskriftsartikel (refereegranskat)abstract
    • Objective-The principal aim of the present study was to explore the feasibility of using whole-body magnetic resonance angiography to assess atherosclerosis in different vascular territories in a cohort of elderly. Methods and Results-Three hundred six 70-year-old subjects (145 women, 161 men) recruited from a population-based cohort study (Prospective Investigation of the Vasculature in Uppsala Seniors, ie, the PIVUS study) underwent 1.5-T whole-body magnetic resonance angiography with gadodiamide. The arteries were divided into 26 segments. In total, 7956 vessel segments were evaluated with 7900 segments (99.3%) possible to evaluate. Of these, 7186 segments (91%) were normal. Luminal narrowing of ≥50% was observed in 9 (1.5%) of the renal arteries, 12 (1.8%) of the carotid arteries, in 31 segments (1.1%) of the pelvic/upper leg territories, and in 136 segments (6.2%) of territories in the lower leg. Approximately one-third of the sample had no vascular abnormalities, one-third had stenoses of <50%, and the remainder had stenoses ≥50% or occlusions. Six subjects (2%) had aortic aneurysms. In subjects without evident vascular disease, 26% had significant vascular abnormalities. Conclusions-Whole-body magnetic resonance angiography performed with a clinical scanner can be used for quantifying atherosclerosis in different vascular territories in a single examination in an elderly population.
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24.
  • Hansen, Tomas, et al. (författare)
  • Visceral adipose tissue, adiponectin levels and insulin resistance are related to atherosclerosis as assessed by whole-body magnetic resonance angiography in an elderly population
  • 2009
  • Ingår i: Atherosclerosis. - : Elsevier. - 0021-9150 .- 1879-1484. ; 205:1, s. 163-167
  • Tidskriftsartikel (refereegranskat)abstract
    • OBJECTIVE: The principal aim of this study was to determine whether the amount of visceral adipose tissue (VAT) is more related than subcutaneous adipose tissue (SAT) to atherosclerosis assessed by whole-body MRA (WBMRA). A further objective was to investigate whether traditional risk factors, inflammation, or adipokines could explain the hypothesized relationship between VAT and atherosclerosis. METHODS: Men and women aged 70 were recruited from the general population into the Prospective Investigation of The Vasculature in Uppsala Seniors (PIVUS) and 306 of them underwent WBMRA in a clinical 1.5-T scanner. The arterial tree was assessed for degree of stenosis or occlusion and a total atherosclerotic score (TAS) was established. Information on risk factors and BMI and on SAT and VAT, segmented on an axial MR scan was collected. Adiponectin, leptin, and high sensitive C-reactive protein (hsCRP) were measured in serum. HOMA index was used as a marker of insulin resistance. RESULTS: VAT was related to TAS independently of gender, total obesity (BMI), amount of SAT, hsCRP and also to the traditional risk factors included in the Framingham risk score (FRS) in an elderly population. Adiponectin or the HOMA insulin resistance, but not leptin or VAT, together with FRS was significantly related to TAS in a multiple censored regression model. CONCLUSION: Adiponectin attenuated the relationship between VAT and TAS, suggesting that adiponectin and insulin resistance is an important link between visceral adiposity and atherosclerosis.
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25.
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26.
  • Hansen, Tomas, et al. (författare)
  • Whole-body screening of atherosclerosis with magnetic resonance angiography.
  • 2007
  • Ingår i: Topics in Magnetic Resonance Imaging (TMRI). - : Ovid Technologies (Wolters Kluwer Health). - 0899-3459 .- 1536-1004. ; 18:5, s. 329-337
  • Tidskriftsartikel (refereegranskat)abstract
    • With whole-body magnetic resonance angiography (WBMRA), it is possible to examine the whole arterial tree except intracranial and coronary vessels in a single examination without the risks involved in ionizing radiation or arterial cannulation. Whole-body magnetic resonance angiography is well suited for repeated clinical examinations in patients with systemic diseases such as vasculitis or atherosclerosis and can also be used for scientific purposes. On the basis of the WBMRA overview, a possible further development of the WBMRA concept can be to perform further acquisitions at sites with atherosclerotic plaques with higher-resolution scans to determine the degree of stenosis more accurately or to achieve plaque characterization. A total validation of WBMRA compared with digital subtraction angiography (DSA) is not possible owing to the hazards of ionizing radiation. Studies have shown a high sensitivity and specificity for the pelvic and lower limb arteries in comparison with DSA. No systematic validation against DSA has been performed for the renal, aortic, and carotid arteries. Various methods have been used, however, for confirmation of vascular abnormalities found on WBMRA such as ultrasonography, dedicated MRA, or DSA, with reasonably high agreement. The WBMRA method has not been studied with regard to prediction of future cardiovascular (CV) events, as have intima media thickness, coronary artery calcium scoring, and the ankle-brachial index. The full usefulness of WBMRA in an epidemiological setting and as a complementary screening tool for assessing CV risk still needs to be validated against future CV events.
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27.
  • Hennings, Joakim, et al. (författare)
  • Computed tomography, magnetic resonance imaging and 11C-metomidate positron emission tomography for evaluation of adrenal incidentalomas
  • 2009
  • Ingår i: European Journal of Radiology. - : Elsevier BV. - 0720-048X .- 1872-7727. ; 69:2, s. 314-23
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND: Given the higher sensitivity of modern computed tomography (CT) scanners, adrenal incidentalomas are being discovered increasingly often. This implies a growing quantitative diagnostic and clinical problem. CT and/or magnetic resonance imaging (MRI) and usually thorough hormonal testing are routinely used to determine the origin of these lesions. Recently, positron emission tomography (PET) using the tracer (11)C-metomidate (MTO) has been established as an alternative diagnostic method with high sensitivity for identifying adrenocortical lesions. The aim of this study was to evaluate the clinical use and value of MTO-PET compared to CT and MRI in the characterisation and work-up of adrenal incidentalomas. METHODS: Initially, we retrospectively evaluated 20 adrenal incidentalomas in patients who had undergone CT, MRI and MTO-PET and from whom we had either histopathological diagnosis or clinical follow-up data. After this analysis we conducted a prospective study in order to compare the imaging modalities. In the latter study, 24 incidentalomas were imaged by CT, MRI and MTO-PET and the results were correlated to those from histopathology (n=8) and clinical diagnosis after follow-up (n=16). RESULTS: In the retrospective analysis, MRI and especially MTO-PET, correlated well to histopathology and clinical diagnosis after follow-up, whereas specificity with CT was low. This was possibly due to the presence of several haematomas/fibrosis which were misdiagnosed as adrenocortical adenomas. In the prospective cohort, sensitivity and specificity with CT were 0.71 and 1.0, respectively, and further characterisation by MRI increased these values to 0.86 and 1.0, whereas maximum sensitivity and specificity were reached when MTO-PET was added. CONCLUSION: The diagnosis of an adrenocortical adenoma may be established by CT in most patients and by MRI in an additional number. For the few remaining patients needing further characterisation, MTO-PET is advantageous as an additional imaging modality.
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28.
  • Johansson, Lars, et al. (författare)
  • Lipid Mobilization Following Roux-en-Y Gastric Bypass Examined by Magnetic Resonance Imaging and Spectroscopy
  • 2008
  • Ingår i: Obesity Surgery. - : Springer Science and Business Media LLC. - 0960-8923 .- 1708-0428. ; 18:10, s. 1297-1304
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND: Recent developments of magnetic resonance imaging (MRI) and spectroscopy have made it possible to quantify lipid deposited in different tissues. To what extent an improvement of glucose tolerance shortly after Roux-en-Y gastric bypass surgery (RYGBP) is reflected in lipid levels in liver and skeletal muscle, markers of insulin resistance, has not been clarified. METHODS: Whole-body MRI and MR spectroscopy (MRS) of liver and muscle and measurements of biochemical markers of glucose and lipid metabolism were performed at baseline and 1, 6, and 12 months following surgery in seven morbidly obese women. Volumes of adipose tissue depots and liver and muscle lipids were assessed from the MRI/MRS data. RESULTS: At 1 month postoperatively, body mass index and visceral and subcutaneous adipose tissues were reduced by 9%, 26%, and 10%, respectively, whereas no reductions in intrahepatocellular or skeletal intramyocellular lipid concentrations were found. Free fatty acid and beta-hydroxybutyrate levels were elevated two- and sixfold, respectively; glucose and insulin levels were lowered, indicating increased insulin sensitivity. Further weight loss up to 1 year was associated with reductions in all investigated lipid depots investigated, with the exception of the intramyocellular compartment. CONCLUSION: RYGBP causes rapid lipid mobilization from visceral and subcutaneous adipose depots and enhanced free fatty acid flux to the liver. An exceptional disconnection between liver fat and insulin sensitivity occurs in the early dynamic phase after surgery. However, in the late phase, the energy restriction imposed by the surgical procedure also reduces the liver lipids, but not the intramyocellular lipids.
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29.
  • Johansson, Lars, 1966- (författare)
  • The Utility of Ultrasmall Superparamagnetic Iron Oxide Contrast Agents for Cardiovascular Magnetic Resonance Imaging
  • 2005
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • The purpose of this thesis was to investigate the utility of the Ultrasmall Superparamagnetic Iron Oxide Particle (USPIO), NC100150 Injection for assessment of macro- and microvascular morphology and function using magnetic resonance imaging. The feasibility of NC100150 Injection was tested for the following applications: Coronary angiography, Thrombus detection, Cardiac function, Myocardial perfusion, Assessment of myocardial blood volume and water exchange and finally assessment of endothelial integrity of the myocardium.The test method included computer simulations, in vitro, animal and clinical experiments. The computer simulations included propagation of longitudinal magnetization in non-steady state acquisitions. Animal models used were coronary artery stenosis in pigs, thrombus formation in the jugular vein in pigs, normal pig myocardium and transplanted hearts in rats. A human study of patients with suspected coronary artery disease was also performed.The results showed that angiography using an USPIO is less efficient in the coronary arteries than in the peripheral arteries. Direct targeting to thrombus using an USPIO is possible but will be limited by the spatial resolution. An USPIO will enhance gradient echo imaging of cardiac function. T2-weighted myocardial perfusion imaging is feasible as well as assessment of myocardial blood volume and endothelial integrity.Due to physiological limitations and technical development the utility of NC100150 Injection for assessment of the macrovascular morphology is limited.However for the assessment of microvascular function, especially perfusion and permeability, NC100150 Injection may contribute to a successful implementation of these methods.
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30.
  • Knutson, Tina, et al. (författare)
  • Increased understanding of intestinal drug permeability determined by the LOC-I-GUT approach using multislice computed tomography
  • 2009
  • Ingår i: Molecular pharmaceutics. - : American Chemical Society (ACS). - 1543-8384 .- 1543-8392. ; 6:1, s. 2-10
  • Tidskriftsartikel (refereegranskat)abstract
    • This study further evaluated the in vivo single-pass perfusion technique (LOC-I-GUT) in three different ways. First, the intestinal radius of the human small intestinal segment was measured on plain X-ray films; second, evaluation was performed by applying multislice computed tomography investigations; and third, furosemide was used as model drug in a transport study. In total 17 (6 + 4 +7) intubation/perfusion studies were performed in healthy volunteers. Mixobar was used as a positive radiographic contrast agent in the first six volunteers when plain film examination was made, followed by four studies using multislice computed tomography. Mantel area calculations of the perfused segment after X-ray investigations using barium as contrast were determined to be 101.0 +/- 2.9 cm2. Maximal dilatation of the closed segment with room air as contrast and using MSCT revealed a mantel area of 121.30 +/- 7.0 cm2 (P < 0.01). Thus, the mantle area increased a further 20% when the bowel was fully distended, reflecting different physiologic distention patterns for air and fluid. A jejunal single-pass perfusion study was performed in a further seven volunteers. In each experiment furosemide was perfused during 200 min, and in the treatment period (100-200 min), fexofenadine was added to the perfusion solution. The mean (+/-SD) P (eff) for furosemide was 0.17 +/- 0.07 and 0.12 +/- 0.09 x 10-4 cm/s in the control and treatment period, respectively. This study showed that the calculation of human in vivo permeability is based on physiological values, which are important for the wide application of these in vivo permeability data in physiologically based pharmacokinetic modeling.
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31.
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32.
  • Kullberg, Joel, et al. (författare)
  • Automated Assessment of Whole-Body Adipose Tissue Depots From Continuously Moving Bed MRI : A Feasibility Study
  • 2009
  • Ingår i: Journal of Magnetic Resonance Imaging. - : Wiley. - 1053-1807 .- 1522-2586. ; 30:1, s. 185-193
  • Tidskriftsartikel (refereegranskat)abstract
    • PURPOSE: To present an automated algorithm for segmentation of visceral, subcutaneous, and total volumes of adipose tissue depots (VAT, SAT, TAT) from whole-body MRI data sets and to investigate the VAT segmentation accuracy and the reproducibility of all depot assessments. MATERIALS AND METHODS: Repeated measurements were performed on 24 volunteer subjects using a 1.5 Tesla clinical MRI scanner and a three-dimensional (3D) multi-gradient-echo sequence (resolution: 2.1 x 2.1 x 8 mm(3), acquisition time: 5 min 15 s). Fat and water images were reconstructed, and fully automated segmentation was performed. Manual segmentation of the VAT reference was performed by an experienced operator. RESULTS: Strong correlation (R = 0.999) was found between the automated and manual VAT assessments. The automated results underestimated VAT with 4.7 +/- 4.4%. The accuracy was 88 +/- 4.5% and 7.6 +/- 5.7% for true positive and false positive fractions, respectively. Coefficients of variation from the repeated measurements were: 2.32 % +/- 2.61%, 2.25% +/- 2.10%, and 1.01% +/- 0.74% for VAT, SAT, and TAT, respectively. CONCLUSION: Automated and manual VAT results correlated strongly. The assessments of all depots were highly reproducible. The acquisition and postprocessing techniques presented are likely useful in obesity related studies.
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33.
  • Kullberg, Joel, et al. (författare)
  • Practical approach for estimation of subcutaneous and visceral adipose tissue
  • 2007
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 27:3, s. 148-153
  • Tidskriftsartikel (refereegranskat)abstract
    • Objectives: The first objective was to investigate the correlations between anthropometrical measurements and visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) in two cohorts differing in age using magnetic resonance imaging (MRI) as reference. A second objective was to investigate the potential usage of abdominal diameters in practical estimation of adipose tissue compartments using these cohorts. Methods: Measurements of body mass index, waist circumference, sagittal abdominal diameter (sagittal AD) and transverse abdominal diameter (transverse AD) were obtained from 336 volunteers of age 14-70 years. Manual measurements of VAT and SAT from single slice MRI at the L4-L5 level were used as reference. The abdominal diameters were measured from the MR images. Linear correlations between the anthropometrical measurements and the reference were studied. Results: Sagittal AD showed the strongest correlation to VAT (r > 0·780, P<0·0001) and transverse AD was found to give information about the amount of SAT (r > 0·866, P<0·0001). The ellipse spanned by the sagittal AD and the transverse AD was strongly correlated to the total amount of adipose tissue (r ≥ 0·962 P<0·0001). Conclusion: Strong correlations were found between sagittal and transverse abdominal diameters, assessed using MRI, and VAT and SAT, respectively. These results suggest the use of abdominal diameters in practical estimations of VAT and SAT depots.
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34.
  • Kullberg, Joel, et al. (författare)
  • Whole-body adipose tissue analysis: comparison of MRI, CT and dual energy X-ray absorptiometry.
  • 2009
  • Ingår i: The British journal of radiology. - : British Institute of Radiology. - 1748-880X .- 0007-1285. ; 82:974, s. 123-30
  • Tidskriftsartikel (refereegranskat)abstract
    • The aim of this study was to validate a recently proposed MRI-based T(1)-mapping method for analysis of whole-body adipose tissue (AT) using an established CT protocol as reference and to include results from dual energy X-ray absorptiometry (DEXA). 10 subjects, drawn from the Swedish Obese Subjects Sibling-pairs study, were examined using CT, MRI and DEXA. The CT analysis was based on 28 imaged slices. T(1) maps were calculated using contiguous MRI data from two different gradient echo sequences acquired using different flip angles. CT and MRI comparison was performed slice-wise and for the whole-body region. Fat weights were compared between all three modalities. Strong correlations (r > or = 0.977, p<0.0001) were found between MRI and CT whole-body and AT volumes. MRI visceral AT volume was underestimated by 0.79 +/- 0.75 l (p = 0.005), but total AT was not significantly different from that estimated by CT (MRI - CT = -0.61+/-1.17 l; p = 0.114). DEXA underestimated fat weights by 5.23 +/- 1.71 kg (p = 0.005) compared with CT. MRI underestimated whole-body volume by 2.03 +/- 1.61 l (p = 0.005) compared with CT. Weights estimated either by CT or by DEXA were not significantly different from weights measured using scales. In conclusion, strong correlations were found between whole-body AT results from CT, MRI-based T(1) mapping and DEXA. If the differences between the results from T(1)-mapping and CT-based analysis are accepted, the T(1)-mapping method allows fully automated post-processing of whole-body MRI data, allowing longitudinal whole-body studies that are also applicable for children and adolescents.
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35.
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36.
  • Lind, Lars, et al. (författare)
  • Atherosclerosis measured by whole body magnetic resonance angiography and carotid artery ultrasound is related to arterial compliance, but not to endothelium-dependent vasodilation : the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study
  • 2009
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 29:5, s. 321-9
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND: Arterial compliance and endothelium-dependent vasodilation are two characteristics of the vessel wall. In the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study, we studied the relationships between arterial compliance and endothelium-dependent vasodilation versus atherosclerosis as measured with two imaging modalities. METHODS: In the population-based PIVUS study (1016 subjects aged 70), arterial compliance was determined by ultrasound in the carotid artery and the stroke volume to pulse pressure ratio by echocardiography, while endothelium-dependent vasodilation was assessed by the invasive forearm technique with acetylcholine and brachial artery ultrasound. Intima-media thickness was evaluated by ultrasound in the carotid artery (n = 954). Stenosis in the carotid, aorta, renal, upper and lower leg arteries were determined by magnetic resonance angiography in a random subsample of 306 subjects. RESULTS: After adjustments for gender, Framingham risk score, obesity, myocardial infarction and stroke, distensibility in the carotid artery and the stroke volume to pulse pressure ratio were both significantly related to a weighted index of stenosis in the five arterial territories evaluated by magnetic resonance angiography (p<0.02 for both). Distensibility in the carotid artery (P = 0.021), but not the stroke volume to pulse pressure ratio (P = 0.08), was also significantly related to intima-media thickness. CONCLUSION: In the elderly population, atherosclerosis is mainly related to arterial compliance, but not to endothelium-dependent vasodilation in peripheral conduit or resistance vessels.
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37.
  • Lind, Lars, et al. (författare)
  • Vasodilation and visceral fat in elderly subjects : the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study
  • 2007
  • Ingår i: Atherosclerosis. - : Elsevier BV. - 0021-9150 .- 1879-1484. ; 194:2, s. e64-e71
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND: Although obesity has long been recognised as a cardiovascular risk factor, only in recent years has the role of visceral adipose tissue (VAT) been evaluated. In the Prospective Study of the Vasculature in Uppsala Seniors (PIVUS) study, we related VAT and other obesity indices to endothelium-dependent vasodilation in both capacitance and resistance arteries. METHODS AND RESULTS: In this population-based study, 1016 subjects aged 70 were evaluated by the invasive forearm technique with acetylcholine (EDV) and brachial artery ultrasound to assess flow-mediated vasodilation (FMD). Intra-abdominal visceral (VAT) and subcutaneous adipose tissue (SAT) were determined by magnetic resonance imaging in a random sample of 287 subjects. EDV, but not FMD, was inversely related to VAT, SAT, BMI and the waist/hip ratio (r=-0.23, -0.16, -0.21 and -0.11, respectively, p=0.05-0.001 after adjustment for gender). In multiple regression analysis however, only VAT was an independent predictor of EDV. Similar results were obtained for endothelium-independent vasodilation (EIDV, infusion of sodium nitroprusside in the brachial artery). CONCLUSIONS: Both endothelium-dependent and independent vasodilation in the forearm resistance arteries, but not FMD in the brachial artery, was reduced in elderly subjects with increased intra-abdominal adipose tissue mass. This finding suggests deterioration in general vasoreactivity mainly in resistance arteries in elderly subjects with intra-abdominal obesity.
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38.
  • Mirza, Majd A I, et al. (författare)
  • Relationship between circulating FGF23 and total body atherosclerosis in the community
  • 2009
  • Ingår i: Nephrology, Dialysis and Transplantation. - : Oxford University Press (OUP). - 0931-0509 .- 1460-2385. ; 24:10, s. 3125-3131
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND: Fibroblast growth factor-23 (FGF23) is a regulator of mineral metabolism and has been suggested to play a role in vascular calcification in chronic kidney disease (CKD). Data on the association between FGF23 and atherosclerosis, both in CKD and in the community, is limited. METHODS: The total body atherosclerosis score (AS) was determined by a magnetic resonance imaging-based angiography in 306 elderly men and women, representing a subsample of the community-based PIVUS cohort. Subjects were divided into three categories based on AS: AS = 0, low AS and high AS. Serum FGF23 was measured using a two-site monoclonal antibody ELISA. RESULTS: In continuous and multi-category regression models, higher FGF23 was associated with a significant increase in the odds of having a high AS (OR 1.43, CI 1.06-1.92 to OR 3.01, CI 1.52-5.99). This association was stronger in individuals with eGFR <60 mL/min/1.73 m(2) (n = 27), reaching a nearly 6-fold increase in the odds for a high AS in the upper FGF23 tertile (OR 5.64, CI 2.78-11.5). We found weaker support for a relationship between FGF23 and the presence of atherosclerosis as subjects in the highest FGF23 tertile had an increased risk for an AS > 0 in crude models (OR 1.93, CI 1.05-3.55), but this was not statistically significant in adjusted (OR 1.42, CI 0.74-1.72) models. CONCLUSIONS: We provide novel evidence supporting an association between serum FGF23 and total body atherosclerosis in the community. Additional studies are warranted to determine the prospective relationship between FGF23 and atherosclerosis, and whether FGF23 is a modifiable cardiovascular risk factor.
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39.
  • Morell, Arvid, 1973-, et al. (författare)
  • Quantitative renal cortical perfusion in human subjects with magnetic resonance imaging using iron-oxide nanoparticles: influence of T1 shortening
  • 2008
  • Ingår i: Acta radiologica (Stockholm, Sweden : 1987). - : SAGE Publications. - 1600-0455 .- 0284-1851. ; 49:8, s. 955-62
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND: Using conventional contrast agents, the technique of quantitative perfusion by observing the transport of a bolus with magnetic resonance imaging (MRI) is limited to the brain due to extravascular leakage. PURPOSE: To perform quantitative perfusion measurements in humans with an intravascular contrast agent, and to estimate the influence of the T1 relaxivity of the contrast agent on the first-pass response. MATERIAL AND METHODS: Renal cortical perfusion was measured quantitatively in six patients with unilateral renal artery stenosis using a rapid gradient double-echo sequence in combination with an intravenous bolus injection of NC100150 Injection, an intravascular contrast agent based on iron-oxide nanoparticles. The influence of T1 relaxivity was measured by comparing perfusion results based on single- and double-echo data. RESULTS: The mean values of cortical blood flow, cortical blood volume, and mean transit time in the normal kidneys were measured to 339+/-60 ml/min/100 g, 41+/-8 ml/100 g, and 7.3+/-1.0 s, respectively, based on double-echo data. The corresponding results based on single-echo data, which are not compensated for the T1 relaxivity, were 254+/-47 ml/min/100 g, 27+/-3 ml/100 g, and 6+/-1.2 s, respectively. CONCLUSION: The use of a double-echo sequence enabled elimination of confounding T1 effects and consequent systematic underestimation of the perfusion.
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40.
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41.
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42.
  • Penno, Eva, et al. (författare)
  • Macrophage uptake of ultra-small iron oxide particles for magnetic resonance imaging in experimental acute cardiac transplant rejection
  • 2006
  • Ingår i: Acta Radiologica. - : SAGE Publications. - 0284-1851 .- 1600-0455. ; 47:3, s. 264-271
  • Tidskriftsartikel (refereegranskat)abstract
    • PURPOSE: To discriminate between acutely rejecting and non-rejecting transplanted hearts using a blood pool contrast agent and T2* magnetic resonance imaging (MRI) in a clinical 1.5T scanner. MATERIAL AND METHODS: Allogeneic and syngeneic heterotopic heart transplantations were performed in rats. One allogeneic and one syngeneic group each received either the ultra-small iron oxide particle (USPIO), at two different doses, or no contrast agent at all. MRI was performed on postoperative day 6. Immediately after the MR scanning, contrast agent was injected and a further MRI was done 24 h later. Change in T2* was calculated. RESULTS: No significant difference in change in T2* could be seen between rejecting and non-rejecting grafts in either of the doses, or in the control groups. There was a difference between the allogeneic group that received the higher contrast agent dose and the allogeneic group that did not receive any contrast agent at all. CONCLUSION: In our rat model, measurements of T2* after myocardial macrophage uptake of AMI-227 in a clinical 1.5T scanner were not useful for the diagnosis of acute rejection.
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43.
  • Penno, Eva, 1971- (författare)
  • Studies of Acute Rejection Using Contrast Agents and Magnetic Resonance Imaging
  • 2006
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Solid organ transplantation is today an established form of treatment for end-stage organ disease. Monitoring of graft function and pharmacological therapy constitutes a maze of clinical observations and histological evaluations of biopsy specimens; with the biopsy results playing a decisive role. The aims of this doctoral research were to investigate the feasibility of detecting acute rejection of transplanted organs and monitoring the effect of anti-rejection treatment, with the use of ultrasmall superparamagnetic iron oxide particles (USPIO) and magnetic resonance (MR) imaging with a clinical MR scanner.Allogeneic and syngeneic heterotopic heart transplantations were performed in rats. Three different-sized USPIO were given to one allogeneic and one syngeneic group. The change in MR signal intensity (SI) over time was measured. An increase in SI was interpreted as damage to micro vessels due to the pronounced inflammatory reaction caused by acute rejection, which led to leakage of USPIO into the tissue. A decrease in SI was interpreted as normal vascular structure, since USPIO normally remains in the intravascular space. The same method, using one of the previously tested USPIO, was used in a treatment study in which acute rejection in transplanted rats was induced and subsequently treated. An attempt was also made to detect presence of macrophages in an acutely rejecting graft, since this cell type plays an important role in the acute rejection process; this was done by testing the ability of macrophages to phagocytose the UPSIO compound.In permeability studies with MR imaging all three USPIO tested discriminated between rejecting and non-rejecting grafts without any overlap of the groups. Factors that contributed to the ability to distinguish between grafts were the size and half-life of the particle. We were also able to monitor effects of anti-rejection treatment by studying the vascular permeability of USPIO and MR imaging. We did not succeed in detecting macrophages in the rejecting grafts with USPIO and MR imaging.This thesis presents a novel approach to detection of acute rejection of transplanted organs and to monitoring the effects of anti-rejection treatment using different USPIO contrast agents and MR imaging in a clinical MR scanner.
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44.
  • Penno, Eva, 1971-, et al. (författare)
  • Ultrasmall iron oxide particle contrast agent and MRI can be used to monitor the effect of anti-rejection treatment
  • 2007
  • Ingår i: Transplantation. - : Ovid Technologies (Wolters Kluwer Health). - 0041-1337 .- 1534-6080. ; 84:3, s. 374-379
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND: The purpose of the study was to investigate the feasibility of monitoring anti-rejection treatment using a blood pool contrast agent and magnetic resonance (MR) imaging. METHODS: Allogeneic heterotopic heart transplantations in rats were performed. In one group (treated group), a mild acute rejection was developed and subsequently treated and MR imaging was performed before and after anti-rejection treatment. In the other group (nontreated group), a mild acute rejection was developed and allowed to progress without treatment and MR examinations were performed before and after the advance of the acute rejection. After injecting ultrasmall superparamagnetic contrast agent, the relative change of signal intensity (SI) over time was measured. The SI difference between both radiological investigations for every animal was calculated; hence, every animal served as its own control. RESULTS: In both treated and nontreated groups, a significant difference over time was found between the two MR examinations seen as a decrease in the treated group and an increase in the nontreatment group. CONCLUSION: It is concluded that the effect of anti-rejection treatment can be detected using a blood pool agent and MR imaging, as a change in SI corresponding to changes in the vascular permeability.
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45.
  • Persson, Anders, 1953- (författare)
  • Volume imaging of the abdomen : three-dimensional visualisation of tubular structures in the body with CT and MRI
  • 2005
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • The overwhelming amount of image-based information in modem medicine makes it crucial to develop methods to handle and analyze images and make them comprehensible for users. The aim of this thesis was to study the radiological practice of three-dimensional (3D) visualization of tubular structures in the body with CT and MRI. All the studies cancern 3D imaging of tubular structures with camputed tomography (CT) and magnetic resonance imaging (MRI). The first three studies examine the abdominal aorta; the two later ones the, bile ducts.Study I compared measurements of aorta diameters taken from MR images presented using two visualization methods - maximum intensity projection (MlP) and volume rendering (VRT) - with invasive angiography (DSA) and CT as reference methods. Mean diameters of MR images were smaller than those from DSA and CT when MlP was used, but in general not when VRT was used.Study II evaluated the dependence on the observer and the choice of method and settings during rendering using the same material as in Study 1. In both MlP and VRT, the choice of settings had significant influence on the results. With DSA as the reference method, VRT gave larger measurement errors than MIP when the rendering parameters were set to fixed values, but not if the user was allowed to select the settings freely.Study III evaluated three new techniques for standardizing VRT protocols for MRA. Inter-reader variability and agreement with DSA were studied by comparing diameter measurements of the abdominal aorta obtained by the three new techniques, by VRT with freely chosen parameters and by MlP. All three new methods were significantly better than MlP and VRT with freely chosen parameters conceming inter-observer agreement. Agreement with DSA was significantly better for one of the methods. Standardized protocols seem to have a potential to make VRT a clinically useful alternative to MlP for MR angiography measurements.Study IV evaluated CT imaging of the bile ducts after drip intravenous infusion of the contrast medium iotroxate (CT cholangiography) in terms of adverse effects and visibility. With infusion time adjusted for individual variation in serum bilirubin concentration, a total side-effect frequency of less than 1% was found. A systematic review of previously published studies indicated a frequency of 2.3%. Good contrast excretion and visualization of bile ducts even in patients with elevated bilirubin levels were noted.Study V evaluated the diagnostic benefits of the same imaging method by comparing it with findings from surgery and endoscopic retrograde cholangiopancreatography (ERCP). The consensus sensitivity and specificity for diagnosing biliary stones was 88% and 94%, respectively. The use of VRT improved diagnostic certainty in 14% of the evaluatians, and the visualization of ductal stones was improved in 38% of the positive cases.In conclusion, volume rendering technique with standardized parameters may become a clinically useful tool in the clinical MRI environment. DIC-CT with bilirubin-governed infusion time and volume rendering post-processing produces detailed images of the biliary tree, resulting in good sensitivity and specificity. Moreover the safety is acceptable.
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46.
  • Schwitter, Juerg, et al. (författare)
  • MR-IMPACT : comparison of perfusion-cardiac magnetic resonance with single-photon emission computed tomography for the detection of coronary artery disease in a multicentre, multivendor, randomized trial
  • 2008
  • Ingår i: European Heart Journal. - : Oxford University Press (OUP). - 0195-668X .- 1522-9645. ; 29:4, s. 480-9
  • Tidskriftsartikel (refereegranskat)abstract
    • AIMS: To determine in a multicentre, multivendor trial the diagnostic performance for perfusion-cardiac magnetic resonance (perfusion-CMR) in comparison with coronary X-ray angiography (CXA) and single-photon emission computed tomography (SPECT). METHODS AND RESULTS: Of 241 eligible patients from 18 centres, 234 were randomly dosed with 0.01, 0.025, 0.05, 0.075, or 0.1 mmol/kg Gd-DTPA-BMA (Omniscantrade mark, GE-Healthcare) per stress (0.42 mg/kg adenosine) and rest perfusion study. Coronary artery disease (CAD) was defined as diameter stenosis > or =50% on quantitative CXA. Five CMR and eight SPECT studies (of 225 complete studies) were excluded from analyses due to inadequate quality (three blinded readers scored per modality). The comparison of CMR vs. SPECT was based on receiver operating characteristic (ROC) analysis. Perfusion-CMR at the optimal CM dose (0.1 mmol/kg) had similar performance as SPECT, if only the SPECT studies of the 42 patients with this dose were considered [area under ROC curve (AUC): 0.86 +/- 0.06 vs. 0.75 +/- 0.09 for SPECT, P = 0.12]; however, diagnostic performance of perfusion-CMR was better vs. the entire SPECT population (AUC: 0.67 +/- 0.05, n = 212, P = 0.013). CONCLUSIONS: In this multicentre, multivendor trial, ROC analyses suggest perfusion-CMR as a valuable alternative to SPECT for CAD detection showing equal performance in the head-to-head comparison. Comparing perfusion-CMR with the entire SPECT population suggests CMR superiority over SPECT, which warrants further evaluation in larger trials.
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47.
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48.
  • Svantesson, Mia, et al. (författare)
  • Interprofessional ethics rounds concerning dialysis patients : staff's ethical reflections before and after rounds
  • 2008
  • Ingår i: Journal of Medical Ethics. - London : BMJ Publ. Group. - 0306-6800 .- 1473-4257. ; 34:5, s. 407-413
  • Tidskriftsartikel (refereegranskat)abstract
    • OBJECTIVE: To evaluate whether ethics rounds stimulated ethical reflection. METHODS: Philosopher-ethicist-led interprofessional team ethics rounds concerning dialysis patient care problems were applied at three Swedish hospitals. The philosophers were instructed to stimulate ethical reflection and promote mutual understanding between professions but not to offer solutions. Questionnaires directly before and after rounds were answered by 194 respondents. The analyses were primarily content analysis with Boyd's framework but were also statistical in nature. FINDINGS: Seventy-six per cent of the respondents reported a moderate to high rating regarding new insights on ethical problem identification, but the ethics rounds did not seem to stimulate the ethical reflection that the respondents had expected (p < 0.001). Dominant new insights did not seem to fit into traditional normative ethics but were instead interpreted as hermeneutic ethics. This was illustrated in the extended perspective on the patient and increased awareness of relations to other professions. Regarding insights into how to solve ethical problems, the request for further interprofessional dialogue dominated both before and after rounds. CONCLUSION: The findings show the need for interprofessional reflective ethical practice but a balance between ethical reflection and problem solving is suggested if known patients are discussed. Further research is needed to explore the most effective leadership for reflective ethical practice.
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49.
  • Svantesson, Mia, et al. (författare)
  • Learning a way through ethical problems : Swedish nurses’ and doctors’ experiences from one model of ethics rounds
  • 2008
  • Ingår i: Journal of Medical Ethics. - : BMJ. - 0306-6800 .- 1473-4257. ; 34:5, s. 399-406
  • Tidskriftsartikel (refereegranskat)abstract
    • OBJECTIVE: To evaluate one ethics rounds model by describing nurses' and doctors' experiences of the rounds. METHODS: Philosopher-ethicist-led interprofessional team ethics rounds concerning dialysis patient care problems were applied at three Swedish hospitals. The philosophers were instructed to promote mutual understanding and stimulate ethical reflection, without giving any recommendations or solutions. Interviews with seven doctors and 11 nurses were conducted regarding their experiences from the rounds, which were then analysed using content analysis. Findings: The goal of the rounds was partly fulfilled. Participants described both positive and negative experiences. Good rounds included stimulation to broadened thinking, a sense of connecting, strengthened confidence to act, insight into moral responsibility and emotional relief. Negative experiences were associated with a sense of unconcern and alienation, as well as frustration with the lack of solutions and a sense of resignation that change is not possible. The findings suggest that the ethics rounds above all met the need of a forum for crossing over professional boundaries. The philosophers seemed to play an important role in structuring and stimulating reasoned arguments. The nurses' expectation that solutions to the ethical problems would be sought despite explicit instructions to the contrary was conspicuous. CONCLUSION: When assisting healthcare professionals to learn a way through ethical problems in patient care, a balance should be found between ethical analyses, conflict resolution and problem solving. A model based on the findings is presented.
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50.
  • Svantesson, Mia, et al. (författare)
  • Nurses' and physicians' opinions on aggressiveness of treatment for general ward patients
  • 2006
  • Ingår i: Nursing Ethics. - : SAGE Publications. - 0969-7330 .- 1477-0989. ; 13:2, s. 147-162
  • Tidskriftsartikel (refereegranskat)abstract
    • The aim of this study was to evaluate agreement between nurses' and physicians' opinions regarding aggressiveness of treatment and to investigate and compare the rationales on which their opinions were based. Structured interviews regarding 714 patients were performed on seven general wards of a university hospital. The data gathered were then subjected to qualitative and quantitative analyses. There was 86% agreement between nurses' and physicians' opinions regarding full or limited treatment when the answers given as 'uncertain' were excluded. Agreement was less (77%) for patients with a life expectancy of less than one year. Disagreements were not associated with professional status because the physicians considered limiting life-sustaining treatment as often as the nurses. A broad spectrum of rationales was given but the results focus mostly on those for full treatment. The nurses and the physicians had similar bases for their opinions. For the majority of the patients, medical rationales were used, but age and quality of life were also expressed as important determinants. When considering full treatment, nurses used quality-of-life rationales for significantly more patients than the physicians. Respect for patients' wishes had a minor influence.
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