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- Bjerner, Tomas, et al.
(författare)
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Evaluation of nonperfused myocardial ischemia with MRI and an intravascular USPIO contrast agent in an ex vivo pig model
- 2000
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Ingår i: Journal of Magnetic Resonance Imaging. - 1053-1807 .- 1522-2586. ; 12:6, s. 866-872
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Tidskriftsartikel (refereegranskat)abstract
- The ultrasmall superparamagnetic iron oxide (USPIO) preparation NC100150 Injection (Clariscan; Nycomed Imaging, Oslo, Norway) was tested for its ability to delineate nonperfused myocardium under steady-state conditions. An experimental animal model of focal myocardial ischemia induced by ligation of the distal part of the left anterior descending artery was used. The contrast agent was administered in four doses: 0, 4, 8, and 12 mg Fe/kg body weight. Magnetic resonance examination ex vivo, including T1-, T2-, and T2*-weighted sequences, was performed. Nonperfused myocardium was determined by fluorescein. The best delineation of nonperfused myocardium was found with a T1-weighted inversion recovery/turbo spin-echo sequence and doses of 4 and 8 mg Fe/kg body weight, where 95% of the volume was discernible at the dose of 4 mg Fe/kg body weight. The results suggest that steady-state imaging by T1-weighted sequence with the use of NC100150 Injection to delineate nonperfused myocardium is feasible. J. Magn. Reson. Imaging 2000;12:866-872.
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| 2. |
- Bjerner, Tomas, et al.
(författare)
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First-Pass Myocardial Perfusion MR Imaging with Outer-Volume Suppression and the Intravascular Contrast Agent NC100150 Injection : Preliminary Results in Eight Patients.
- 2001
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Ingår i: Radiology. - : Radiological Society of North America (RSNA). - 0033-8419 .- 1527-1315. ; 221:3, s. 822-826
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Tidskriftsartikel (refereegranskat)abstract
- The authors evaluated the feasibility of combining single-shot T2-weighted turbo spin-echo magnetic resonance (MR) imaging and first-pass myocardial perfusion MR imaging with an intravascular ultrasmall superparamagnetic iron oxide (USPIO) contrast agent, NC100150 Injection (3 mg of iron per kilogram of body weight). Eight patients with coronary vessel disease underwent T2-weighted turbo spin-echo MR imaging (in-plane resolution, 1-2 mm) during the first pass of the USPIO contrast agent. The mean decrease in signal intensity in myocardium perfused by a nonstenotic coronary artery was 59% +/- 13 (SD) (P < .012) This method is feasible for imaging of myocardial perfusion.
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| 4. |
- Bjerner, Tomas, et al.
(författare)
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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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Ingår i: Investigative Radiology. - 0020-9996 .- 1536-0210. ; 39:8, s. 470-478
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Tidskriftsartikel (refereegranskat)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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| 8. |
- Sörensen, Jens, et al.
(författare)
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Simple and accurate assessment of forward cardiac output by use of 1-[11C]acetate PET verified in a pig model
- 2003
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Ingår i: Journal of Nuclear Medicine. - 0161-5505 .- 1535-5667. ; 44:7, s. 1176-1183
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Tidskriftsartikel (refereegranskat)abstract
- Dynamic 1-(11)C-acetate PET (AC-PET) allows quantification of myocardial blood flow and oxidative metabolism. We wanted to determine the accuracy of AC-PET in measuring cardiac output (CO) using first-pass analysis and the indicator dilution principle. Further, we wanted to investigate the pulmonary uptake of acetate in relation to left atrial filling pressures and ventricular function.METHODS: Twenty-four steady-state experiments were performed in 5 domestic pigs. Pulmonary capillary wedge pressure (PCWP) and CO by thermodilution (CO(thermo)) were recorded invasively simultaneous with AC-PET scans at baseline (n = 9), dobutamine infusion (n = 6), high-dose metoprolol and morphine (n = 6), and angiotensinamide infusion (n = 3). 1-(11)C-Acetate was injected as a rapid manual bolus. Regions of interest (ROIs) were placed in the right (RV) and left (LV) heart cavities. Time-activity curves were constructed and the area under the curve (AUC) was integrated from beginning the scan to the time of visually determined recirculation by simple arithmetic. CO by PET (CO(PET)) was calculated as injected dose/AUC. Image handling and curve analysis were repeated by a blinded observer. Total pulmonary extravascular retention of (11)C, expressed as percentage of injected dose (lung-uptake %ID), was measured using a combination of transmission, (15)O-carbon monoxide, and AC-PET scans.RESULTS: CO(thermo) ranged from 2.1 to 8.2 L/min. CO(PET) determined from both LV and RV was linearly related to CO(thermo) with slopes close to 1 (LV, r = 0.98; RV, r = 0.96; both P < 0.001). Interobserver reproducibility was r = 0.98, P < 0.001. The PCWP range was 6-14 mm Hg and the lung-uptake %ID was 2.7-8.5 %ID. When normalized to baseline, lung-uptake %ID was correlated with PCWP (r = 0.56, P = 0.01) and linearly correlated with LV input resistance (PCWP divided by CO(thermo); r = 0.91, P < 0.001). When both lung-uptake %ID and stroke volume were normalized to baseline, a piecewise linear relation was found (r = 0.95, P < 0.001).CONCLUSION: Our results suggest that measurements of CO by AC-PET are feasible and accurate. Using RV ROIs might favor CO measurements by any injectable PET tracer. The lung-uptake %ID might be useful in evaluation of pulmonary congestion, but further studies are needed.
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| 9. |
- Zemgulis, Vitas, et al.
(författare)
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Discrepant outcome between myocardial energy-related metabolites and infarct size limitation during retroperfusion of the coronary sinus
- 2001
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Ingår i: Scandinavian Journal of Clinical and Laboratory Investigation. - 0036-5513 .- 1502-7686. ; 61:8, s. 651-662
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The basic idea of retroperfusion of the coronary sinus (RCS) is to ameliorate detrimental consequences of myocardial ischaemia. Several experimental models of RCS have been introduced, most with an emphasis on functional myocardial status. Since only few studies have been devoted to energy metabolic considerations and none to continuous monitoring of energy-related metabolites of myocardium during RCS, we here present such a study using microdialysis. This study comprised the following components: Coronary occlusion and drainage on the beating heart with RCS-assist (60 min), hypothermic (30 degrees C) extracorporeal circulation (ECC) and cardioplegia (45 min), reperfusion and rewarming to 38 degrees C on ECC (30 min). The microdialysis analytical outcome mainly reflected anaerobic energy metabolism in potentially ischaemic myocardium. Additionally, a pronounced increase of microdialysate content of lactate, pyruvate and guanosine was observed in non-ischaemic myocardium especially during the reperfusion phase. The planimetric calculation revealed an infarct size reduction from 69% to 19% and was not correlated to clear-cut improvements of potentially ischaemic myocardial energy metabolism. We conclude that prolonged (60 min) anaerobic energy metabolism does not pose an immediate threat to cell viability but could even sustain myocyte survival.
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| 10. |
- Zemgulis, Vitas, et al.
(författare)
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Energy-related metabolites during and after induced myocardial infarction with special emphasis on the reperfusion injury after extracorporeal circulation
- 2001
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Ingår i: Acta Physiologica Scandinavica. - : Wiley. - 0001-6772 .- 1365-201X. ; 171:2, s. 129-143
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Tidskriftsartikel (refereegranskat)abstract
- In the clinical setting great efforts have been made with contradictory results to operate upon acutely myocardial ischaemic patients. The reasons for the absence of clear-cut results are not well understood nor are they scientifically explored. To resolve this problem further, we attempted to design an experimental in vivo model to mimic acute myocardial ischaemia followed by extracorporeal circulation (ECC) and reperfusion. One of the main targets of our protocol was monitoring of myocardial energy metabolism by microdialysis (MCD) during the periods of coronary occlusion (60 min), hypothermic (30 degrees C) ECC and cardioplegia (45 min), followed by reperfusion with (30 min) and without (60 min) ECC. In eight anaesthetized, open-chest pigs, myocardial lactate, pyruvate, adenosine, taurine, inosine, hypoxanthine and guanosine were sampled with MCD in both ischaemic and non-ischaemic areas. Myocardial area at risk and infarct size were quantified with the modified topographical evaluation methods. The principal finding with this experimental setup was a biphasic release pattern of lactate, adenosine, taurine, inosine, hypoxanthine and guanosine from ischaemic myocardium. Lactate levels were equally high in reperfused ischaemic and non-ischaemic myocardial tissue. Pyruvate demonstrated consistently higher values in non-ischaemic myocardium throughout the experiment. A pattern was discernible, lactate being a marker of compromised cell energy metabolism, and taurine being a marker of disturbed cell integrity. Of special interest was the increased level of pyruvate in microdialysates of non-ischaemic myocardium as compared with its ischaemic counterpart. In conclusion, we found disturbances in energy metabolism and cell integrity not only in ischaemic but also in non-ischaemic tissue during reperfusion implying that non-ischaemic myocardium demonstrated an unexpected accumulation of lactate and pyruvate. These new findings could at least partly be explicatory to the increased risk of heart surgery in connection with acute myocardial infarction.
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