Positive contrast visualization of SPIO-labeled pancreatic islets using echo-dephased steady-state free precession

Patil, Sunil; Jirák, Daniel; Saudek, F; Hájek, Milan; Scheffler, Klaus

doi:10.1007/s00330-010-1909-1

Cited by 14 publications

(19 citation statements)

References 20 publications

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“…8,9 In this study, we successfully reproduced the quantitative association between the novel MRI parameters in the early post-transplant period and the later changes in glycemic levels of recipients. 7 While the efficacy and safety of SPIO labeling in terms of islet viability and ex vivo and in vivo insulin secretion have been established, 8,[10][11][12][13][14][15][16] the results of this study provide in vitro and in vivo evidence for the efficacy and safety of concurrent PEGylation and SPIO labeling. Moreover, our technique for conventional PEGylation without further modification after SPIO labeling is easily performed using procedures similar to those used for standard islet culture.…”

Section: Discussionmentioning

confidence: 75%

Benefits of PEGylation in the early post-transplant period of intraportal islet transplantation as assessed by magnetic resonance imaging of labeled islets

Jin¹,

Oh²,

et al. 2014

Islets

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Section: Discussionmentioning

confidence: 75%

Benefits of PEGylation in the early post-transplant period of intraportal islet transplantation as assessed by magnetic resonance imaging of labeled islets

Jin¹,

Oh²,

et al. 2014

Islets

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“…Iron oxides provide a reliable diagnosis only if native images express a hyper-intense signal which is altered by the contrast agent. However, ongoing research in MR methodology aiming for “white marker sequences” [28], [29] and the new technique of magnetic particle imaging [30] provide the potential to overcome these technical drawback. These new methodologies in combination with the LIBS targeting strategy should allow early detection of unstable atherosclerotic plaques in humans.…”

Section: Discussionmentioning

confidence: 99%

In Vivo Detection of Activated Platelets Allows Characterizing Rupture of Atherosclerotic Plaques with Molecular Magnetic Resonance Imaging in Mice

et al. 2012

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BackgroundEarly and non-invasive detection of platelets on micro atherothrombosis provides a means to identify unstable plaque and thereby allowing prophylactic treatment towards prevention of stroke or myocardial infarction. Molecular magnetic resonance imaging (mMRI) of activated platelets as early markers of plaque rupture using targeted contrast agents is a promising strategy. In this study, we aim to specifically image activated platelets in murine atherothrombosis by in vivo mMRI, using a dedicated animal model of plaque rupture.MethodsAn antibody targeting ligand-induced binding sites (LIBS) on the glycoprotein IIb/IIIa-receptor of activated platelets was conjugated to microparticles of iron oxide (MPIO) to form the LIBS-MPIO contrast agent causing a signal-extinction in T2*-weighted MRI. ApoE−/− mice (60 weeks-old) were fed a high fat diet for 5 weeks. Using a small needle, the surface of their carotid plaques was scratched under blood flow to induce atherothrombosis. In vivo 9.4 Tesla MRI was performed before and repetitively after intravenous injection of either LIBS-MPIO versus non-targeted-MPIO.ResultsLIBS-MPIO injected animals showed a significant signal extinction (p<0.05) in MRI, corresponding to the site of plaque rupture and atherothrombosis in histology. The signal attenuation was effective for atherothrombosis occupying ≥2% of the vascular lumen. Histology further confirmed significant binding of LIBS-MPIO compared to control-MPIO on the thrombus developing on the surface of ruptured plaques (p<0.01).Conclusion in vivo mMRI detected activated platelets on mechanically ruptured atherosclerotic plaques in ApoE−/− mice with a high sensititvity. This imaging technology represents a unique opportunity for noninvasive detection of atherothrombosis and the identification of unstable atherosclerotic plaques with the ultimate promise to prevent strokes and myocardial infarctions.

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“…Mapping B 0 field offsets was also presented with bSSFP by exploiting the signal enhancement next to the off-resonant singularity point of low tip angle bSSFP (18,19). Other methods use imaging gradients for field-compensation and hence acquire positive signal in voxels with high B 0 gradients applied to GRE (20)(21)(22) and bSSFP acquisitions (23). A method obtaining positive contrast that does not need a pulse sequence adaption is based on the off-resonant associated echo-shift in k space, which is mapped to a positive contrast employing standard GRE (24).…”

Section: Introductionmentioning

confidence: 98%

Positive contrast of SPIO‐labeled cells by off‐resonant reconstruction of 3D radial half‐echo bSSFP

Liebmann

Neumayer²,

Reinisch

et al. 2014

NMR in Biomedicine

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This article describes a new acquisition and reconstruction concept for positive contrast imaging of cells labeled with superparamagnetic iron oxides (SPIOs). Overcoming the limitations of a negative contrast representation as gained with gradient echo and fully balanced steady state (bSSFP), the proposed method delivers a spatially localized contrast with high cellular sensitivity not accomplished by other positive contrast methods. Employing a 3D radial bSSFP pulse sequence with half-echo sampling, positive cellular contrast is gained by adding artificial global frequency offsets to each half-echo before image reconstruction. The new contrast regime is highlighted with numerical intravoxel simulations including the point-spread function for 3D half-echo acquisitions. Furthermore, the new method is validated on the basis of in vitro cell phantom measurements on a clinical MRI platform, where the measured contrast-to-noise ratio (CNR) of the new approach exceeds even the negative contrast of bSSFP. Finally, an in vivo proof of principle study based on a mouse model with a clear depiction of labeled cells within a subcutaneous cell islet containing a cell density as low as 7 cells/mm(3) is presented. The resultant isotropic images show robustness to motion and a high CNR, in addition to an enhanced specificity due to the positive contrast of SPIO-labeled cells.

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Positive contrast visualization of SPIO-labeled pancreatic islets using echo-dephased steady-state free precession

Abstract: The echo-dephased SSFP technique could successfully visualise SPIO-labelled human and rat pancreatic islets yielding a positive contrast.

Cited by 14 publications

References 20 publications

Benefits of PEGylation in the early post-transplant period of intraportal islet transplantation as assessed by magnetic resonance imaging of labeled islets

Benefits of PEGylation in the early post-transplant period of intraportal islet transplantation as assessed by magnetic resonance imaging of labeled islets

In Vivo Detection of Activated Platelets Allows Characterizing Rupture of Atherosclerotic Plaques with Molecular Magnetic Resonance Imaging in Mice

Positive contrast of SPIO‐labeled cells by off‐resonant reconstruction of 3D radial half‐echo bSSFP

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