| 1. |
- Bjerner, Tomas, et al.
(author)
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High in-plane resolution T2-weighted magnetic resonance imaging of acute myocardial ischemia in pigs using the intravascular contrast agent NC100150 injection.
- 2004
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In: Investigative Radiology. - 0020-9996 .- 1536-0210. ; 39:8, s. 470-478
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Journal article (peer-reviewed)abstract
- Rationale and Objectives: The intravascular contrast agent NC100150 injection was tested for its ability to demarcate nonperfused myocardium in a porcine model of coronary occlusion. Materials and Methods: A T2-weighted fast spin echo sequence was acquired ex vivo and in vivo during first pass and steady-state circulation of the contrast agent in 2 dosages (2 and 5 mg Fe/kg bw) or saline. Results: Ex vivo, in the high-dose group, the volume of nonperfused myocardium determined from T2-weighted images was 99% of that determined from photographs where perfused myocardium stained with fluorescein. A significantly higher contrast to noise ratio between perfused and nonperfused myocardium was found (both ex and in vivo in steady state) compared with the control group. During first pass, a significant reduction in signal intensity (74 ± 18%) was found in perfused myocardium after contrast injection. Conclusion: NC100150 injection, combined with T2-weighted turbo spin echo imaging, allowed detailed visualization of non-perfused myocardium in the steady state, which corresponded to the area at risk as determined by fluorescein.
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| 3. |
- Briley-Saebo, Karen C., et al.
(author)
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Clearance of iron oxide particles in rat liver : effect of hydrated particle size and coating material on liver metabolism
- 2006
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In: Investigative Radiology. - : Ovid Technologies (Wolters Kluwer Health). - 0020-9996 .- 1536-0210. ; 41:7, s. 560-571
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Journal article (peer-reviewed)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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| 6. |
- Hagiwara, Akifumi, et al.
(author)
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SyMRI of the Brain : Rapid Quantification of Relaxation Rates and Proton Density, With Synthetic MRI, Automatic Brain Segmentation, and Myelin Measurement
- 2017
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In: Investigative Radiology. - : Lippincott Williams & Wilkins. - 0020-9996 .- 1536-0210. ; 52:10, s. 647-657
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Research review (peer-reviewed)abstract
- Conventional magnetic resonance images are usually evaluated using the image signal contrast between tissues and not based on their absolute signal intensities. Quantification of tissue parameters, such as relaxation rates and proton density, would provide an absolute scale; however, these methods have mainly been performed in a research setting. The development of rapid quantification, with scan times in the order of 6 minutes for full head coverage, has provided the prerequisites for clinical use. The aim of this review article was to introduce a specific quantification method and synthesis of contrast-weighted images based on the acquired absolute values, and to present automatic segmentation of brain tissues and measurement of myelin based on the quantitative values, along with application of these techniques to various brain diseases. The entire technique is referred to as "SyMRI" in this review. SyMRI has shown promising results in previous studies when used for multiple sclerosis, brain metastases, Sturge-Weber syndrome, idiopathic normal pressure hydrocephalus, meningitis, and postmortem imaging.
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| 7. |
- Hahn, Gabriele, et al.
(author)
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Pharmacokinetics and safety of gadobutrol-enhanced magnetic resonance imaging in pediatric patients
- 2009
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In: Investigative Radiology. - 0020-9996 .- 1536-0210. ; 44:12, s. 776-783
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Journal article (peer-reviewed)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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| 8. |
- Nygren, A, et al.
(author)
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Red-cell trapping in the rat renal microcirculation induced by low-osmolar contrast media and mannitol
- 1993
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In: Investigative Radiology. - 0020-9996 .- 1536-0210. ; 28:11, s. 1033-1038
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Journal article (peer-reviewed)abstract
- RATIONALE AND OBJECTIVES: In acute renal failure after ischemia, intravascular obstruction by trapped red blood cells in the microvasculature of the renal outer medulla is a consistent finding. The influence of intravenously injected contrast media (CM) on such obstruction was investigated. METHODS: Anesthetized rats were subjected to 45 minutes of unilateral renal ischemia. Red-cell trapping in ischemically injured kidneys and in the contralateral uninjured kidneys was estimated from the intrarenal distribution of 51Cr-labelled erythrocytes after injection of ioxaglate or iopamidol in a dose of 1,600 mg I/kg body weight. As an osmolar control substance, mannitol (950 mOsm/kg) was given to a third group and isotonic Ringer's solution was administered to a fourth group. RESULTS: In the uninjured kidneys, treatment with ioxaglate or mannitol resulted in no red-cell trapping, while the iopamidol-treated group showed red-cell trapping in the inner stripe of the outer medulla in a dose-dependent manner. In the ischemically injured kidneys, both CM and mannitol enhanced the red-cell trapping in the inner stripe of the renal medulla. CONCLUSION: The results indicate that intravenously administered ioxaglate and iopamidol enhance the microvascular obstructions evoked by ischemic injury and that iopamidol may induce local impairment in renal medullary microcirculation in a normal kidney.
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| 9. |
- Sundín, Anders, et al.
(author)
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Computed tomography of experimental liver metastases using an iodinated hepatocyte-specific lipid emulsion : a correlative study in the nude rat
- 1994
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In: Investigative Radiology. - 0020-9996 .- 1536-0210. ; 29:11, s. 963-969
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Journal article (peer-reviewed)abstract
- RATIONALE AND OBJECTIVES: A hepatocyte-specific iodinated lipid emulsion, NRI 757, was used for detection of experimental hepatic metastases. MATERIALS AND METHODS: The study was performed in a correlative model of multiple hepatic metastases from a human colonic cancer implanted in the nude rat. RESULTS: After intravenous injection, normal liver parenchyma remained enhanced for several hours, whereas the uptake in hepatic metastases was negligible. A liver-to-lesion contrast of 45 Hounsfield units (HU) was obtained at a dose of 1 mL NRI 757/kg body weight (BW). In a lesion-by-lesion analysis of 177 metastases ranging in size from 1 to 32 mm, the mean +/- standard deviation overall detection rate for native scanning and contrast-enhanced scanning in vivo and post mortem, 20 +/- 0.4%, 53 +/- 5.2%, and 55 +/- 4.0%, respectively and 28%, 84%, and 82%, retrospectively. When metastatic size also was considered, for native scanning the maximum detection rate of 61% was reached for 8- to 10-mm lesions, whereas for contrast-enhanced computed tomography scanning, 100% of the 5- to 7-mm lesions and 42% of the 1- to 2-mm nodules were detected. CONCLUSION: The use of NRI 757 improved the diagnostic yield considerably.
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| 10. |
- Wikström, Johan, et al.
(author)
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Gadobenate dimeglumine-enhanced magnetic resonance angiography of the pelvic arteries
- 2003
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In: Investigative Radiology. - : Ovid Technologies (Wolters Kluwer Health). - 0020-9996 .- 1536-0210. ; 38:8, s. 504-515
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Journal article (peer-reviewed)abstract
- RATIONALE AND OBJECTIVES: To evaluate 4 doses of gadobenate dimeglumine (Gd-BOPTA) for contrast-enhanced magnetic resonance angiography (CE-MRA) of the pelvic arteries and to compare CE-MRA with unenhanced time-of-flight MRA (2D-TOF-MRA). METHODS: A multicenter Phase II dose-finding study was performed in 136 patients with Gd-BOPTA doses of 0.025, 0.05, 0.1, and 0.2 mmol/kg bodyweight. Evaluation of CE-MRA images and comparison with 2D-TOF-MRA images was performed onsite and by 2 blinded offsite reviewers in terms of subjective image quality, number of lesions detected, and confidence in lesion characterization. RESULTS: Significant (P < 0.05) improvements over unenhanced findings were observed for CE-MRA at all dose levels. For reviewer 1 and the onsite investigators, the overall image quality increased up to a dose of 0.1 mmol/kg and then plateaued. For reviewer 2, increased image quality was noted up to a dose of 0.2 mmol/kg. Significant (P < 0.005) increases in diagnostic confidence on CE-MRA versus unenhanced MRA was observed for all dose groups by reviewer 1 and the onsite investigators and for the 0.1 and 0.2 mmol/kg dose groups by reviewer 2. No serious adverse events were recorded that were attributable to the study drug and no trends in laboratory parameters, vital signs, or electrocardiogram recordings were observed. CONCLUSIONS: Gadobenate dimeglumine-enhanced MRA is safe and significantly more effective than unenhanced 2D-TOF-MRA for imaging the pelvic arteries. A dose of 0.1 mmol/kg appears the most appropriate dose for subsequent Phase III clinical evaluation.
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