| 1. |
- Ebeling Barbier, Charlotte, et al.
(författare)
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Clinically unrecognized myocardial infarction detected at MR imaging may not be associated with atherosclerosis
- 2007
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Ingår i: Radiology. - : Radiological Society of North America (RSNA). - 0033-8419 .- 1527-1315. ; 245:1, s. 103-110
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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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| 2. |
- Torkzad, Michael R., et al.
(författare)
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The Clinical Perspective on Value of 3D, Thin Slice T2-Weighted Images in 3T Pelvic MRI for Tumors
- 2012
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Ingår i: Current Medical Imaging Reviews. - : Bentham Science Publishers Ltd.. - 1573-4056. ; 8:2, s. 76-81(6)
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Tidskriftsartikel (refereegranskat)abstract
- Pelvic imaging is undergoing rapid changes due to increased use of 3-Tesla (3T) magnetic resonance imaging (3T MRI). One of the advantages of 3T could be the possibility for thin section 3-dimensional (3D) imaging which could improve accuracy and at the same time reduce the need for multi-planar imaging needed for conventional T2 imaging (TSE). In the following text we review the advantages of 3D thin section imaging for assessment of pelvic tumors.
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| 5. |
- Bjerner, Tomas, et al.
(författare)
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3D surface rendering of images from multiple MR pulse sequences in the pre-operative evaluation of hepatic lesions
- 1998
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Ingår i: Acta Radiologica. - 0284-1851 .- 1600-0455. ; 39:6, s. 698-700
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Tidskriftsartikel (refereegranskat)abstract
- Segmentation and reconstruction took 1-2 h. To be able to combine the volumes from the different data sets, certain criteria had to be fulfilled: a) the field of view had to be constant; b) the same volume had to be scanned every time which meant that the slice thickness and the number of slices could be adjusted as long as the volume covered was the same; and c) the positioning of each volume had to be identical between every scan. The resulting 3D reconstruction gave the surgeon a clear appreciation of the different lesions and their relation to the different liver segments in the pre-operative planning of hepatic resections.
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| 6. |
- Bjerner, Tomas
(författare)
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Assessment of Myocardial Perfusion with Magnetic Resonance Imaging and an Intravascular Contrast Agent
- 2001
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The intravascular contrast agent NC100150 Injection (Clariscan™) was tested for its ability to induce signal intensity changes in myocardium, both in steady state and during first pass, and thereby demarcating non-perfused myocardium from perfused. Steady state: Ex vivo in pigs and when using 4 mg Fe/kg bodyweight (b.w.) of the contrast agent, a T1-weighted inversion recovery fast spin echo (IR/TSE) sequence could demarcate 95% of the volume of non-perfused myocardium when compared with the volume determined from photographs where non-perfused myocardium was demarcated by fluorescein. A T2*-weighted gradient echo sequence resulted in significantly lower volume estimations of non-perfused myocardium. Under similar conditions and when using 5 mg Fe/kg b.w., a T2-weighted fast spin echo (TSE) demarcated 99% of the volume of non-perfused myocardium. We were not able to implement the IR/TSE sequence in vivo, but the T2-weighted TSE resulted in clear visualization of non-perfused myocardium in vivo in animals. First pass: With a single-shot T2-TSE, one slice was acquired every heartbeat during the first pass of the contrast agent. When using this sequence, non-perfused myocardium was demarcated in animals and the induced signal intensity changes in perfused myocardium (74±18% @ 5 mg Fe/kg b.w.) were comparable to those in patients (59±13 @ 3 mg Fe/kg b.w.), when taking differences in doses into account. Linear dose–response was found in porcine myocardium between R1, R2, and R2* versus dose (0 – 12 mg Fe/kg b.w.) ex vivo and for R1 (in myocardium and blood) versus dose (0 – 5 mg Fe/kg b.w.) in vivo. However, R1 determination in vivo and in the box ex vivo indicated that blood loss (<2/3) from the myocardium occured during the excision of the heart and preparation for the box, meaning that the box situation ex vivo actually corresponds to lower doses in vivo. Finally, the in vivo measurements of R1 in myocardium and blood indicated that at R1 values in blood as high as 13 s-1, the water exchange is in the fast regime through the capillary wall. In conclusion, the feasibility of NC100150 Injection, in steady state and during first pass, for demarcation of non-perfused myocardium when using a T2-weighted TSE sequence has been demonstrated.
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| 7. |
- 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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| 8. |
- 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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| 10. |
- 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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