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Owen D.R.J.,Imperial College London | Owen D.R.J.,Glaxosmithkline | Lindsay A.C.,University of Oxford | Choudhury R.P.,University of Oxford | Fayad Z.A.,Translational and Molecular Imaging Institute
Annual Review of Medicine | Year: 2011

It is now well recognized that the atherosclerotic plaques responsible for thrombus formation are not necessarily those that impinge most on the lumen of the vessel. Nevertheless, clinical investigations for atherosclerosis still focus on quantifying the degree of stenosis caused by plaques. Many of the features associated with a high-risk plaque, including a thin fibrous cap, large necrotic core, macrophage infiltration, neovascularization, and intraplaque hemorrhage, can now be probed by novel imaging techniques. Each technique has its own strengths and drawbacks. In this article, we review the various imaging modalities used for the evaluation and quantification of atherosclerosis. © 2011 by Annual Reviews. All rights reserved. Source

Skajaa T.,Translational and Molecular Imaging Institute | Skajaa T.,Aarhus University Hospital | Zhao Y.,University Utrecht | Van Den Heuvel D.J.,University Utrecht | And 11 more authors.
Nano Letters | Year: 2010

The study of lipoproteins, natural nanoparticles comprised of lipids and apolipoproteins that transport fats throughout the body, is of key importance to better understand, treat, and prevent cardiovascular disease. In the current study, we have developed a lipoprotein-based nanoparticle that consists of a quantum dot (QD) core and Cy5.5 labeled lipidic coating. The methodology allows judicious tuning of the QD/Cy5.5 ratio, which enabled us to optimize Förster resonance energy transfer (FRET) between the QD core and the Cy5.5-labeled coating. This phenomenon allowed us to study lipoprotein- lipoprotein interactions, lipid exchange dynamics, and the influence of apolipoproteins on these processes. Moreover, we were able to study HDL-cell interactions and exploit FRET to visualize HDL association with live macrophage cells. © 2010 American Chemical Society. Source

Bucerius J.,Maastricht University | Bucerius J.,RWTH Aachen | Vijgen G.H.E.J.,NUTRIM | Vijgen G.H.E.J.,Maastricht University | And 11 more authors.
Medicine (United States) | Year: 2015

In this study, we unravel a molecular imaging marker correlated with the known reduction of cardiovascular events (most commonly related to vulnerable plaques) in morbidly obese patients after bariatric surgery (BaS). We prospectively imaged 10 morbidly obese subjects with 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography before and 1 year after BaS. 18F-FDGuptake-which is enhanced in inflamed, atherosclerotic vessels and in metabolically active adipose tissues-was quantified in the carotids, pericardial adipose tissue (PAT), visceral adipose tissue (VAT), as well as brown adipose tissue (BAT). The degree of carotid inflammation was compared to lean and overweight controls. Carotid inflammation significantly declined leading to an 18F-FDG uptake comparable to the 2 control groups. Metabolic activity significantly decreased in PAT and VAT and increased in BAT. BaS leads to a normalization of carotid artery inflammation and a beneficial impact on the metabolic activity in PAT,VAT, and BAT that is related to the metabolic syndrome observed in this patient group. © 2015 Wolters Kluwer Health, Inc. Source

Barrett T.F.,Mount Sinai Hospital | Sarkiss C.A.,Mount Sinai Hospital | Dyvorne H.A.,Translational and Molecular Imaging Institute | Lee J.,Mount Sinai Hospital | And 2 more authors.
World Neurosurgery | Year: 2016

Background Magnetic resonance imaging (MRI) is the imaging modality of choice for the clinical management of brain tumors, and the majority of scanners operate with static magnetic field strengths of 1.5 or 3.0 Tesla (T). During the past decade, ultrahigh field (UHF) MRI has been investigated for its clinical applicability. This meta-analysis evaluates studies pertaining to the application of UHF MRI to patients with brain tumors. Methods The authors performed a systematic review of the literature. Articles relating to application of UHF MRI to brain anatomy and brain tumors with living subjects were included. Studies were grouped into 1 of 3 categories based on area of focus: "Anatomical Structures Involved with Brain Tumors," "Tumor characterization," and "Treatment Monitoring." Comparison studies with extractable outcomes measure data were analyzed for performance of UHF MRI versus clinical field strengths (1.5 T and 3 T). Results Twenty-four studies (361 subjects) met inclusion criteria. The field of study was heterogeneous and rigorous statistical analysis was not possible. Overall, 279 patients with brain tumors scanned at UHF MRI have been reported. Of these, glioma and glioblastoma multiforme are the most commonly studied lesions (38.9% and 24.4%, respectively). In comparison studies between UHF MRI and clinical field strengths, 24 of 51 patients had outcome measures that were better with UHF MRI, 17 of 24 were equivalent at both field strengths, and 9 were worse at UHF MRI. The most common causes of a worse performance were susceptibility artifacts and magnetic field inhomogeneities (3 of 9). Imaging of the pituitary gland, pineal gland veins, cranial nerves, and tumor microvasculature were all shown to be feasible. Conclusions UHF MRI shows promise to improve detection and characterization of brain tumors, preoperative planning for neurosurgical resection, and longitudinal monitoring of the effects of radiation and antibody-based therapies. Technical innovations are needed to overcome field inhomogeneity and susceptibility artifacts in certain regions of the skull. Finally, larger studies comparing 1.5 T, 3.0 T, and 7.0 T or greater will determine whether UHF MRI gains acceptance as a clinical standard. © 2016 Elsevier Inc. All rights reserved. Source

Berker Y.,RWTH Aachen | Berker Y.,Philips | Franke J.,Philips | Salomon A.,Philips | And 12 more authors.
Journal of Nuclear Medicine | Year: 2012

Accurate g-photon attenuation correction (AC) is essential for quantitative PET/MRI as there is no simple relation between MR image intensity and attenuation coefficients. Attenuation maps (m-maps) can be derived by segmenting MR images and assigning attenuation coefficients to the compartments. Ultrashortecho- time (UTE) sequences have been used to separate cortical bone and air, and the Dixon technique has enabled differentiation between soft and adipose tissues. Unfortunately, sequential application of these sequences is time-consuming and complicates image registration. Methods: A UTE triple-echo (UTILE) MRI sequence is proposed, combining UTE sampling for bone detection and gradient echoes for Dixon water-fat separation in a radial 3-dimensional acquisition (repetition time, 4.1 ms; echo times, 0.09/1.09/2.09 ms; field strength, 3 T). Air masks are derived mainly from the phase information of the first echo; cortical bone is segmented using a dual-echo technique. Soft-tissue and adipose-tissue decomposition is achieved using a 3-point Dixon-like decomposition. Predefined linear attenuation coefficients are assigned to classified voxels to generate MRI-based m-maps. The results of ± patients are obtained by comparing m-maps, reciprocal sensitivity maps, reconstructed PET images, and brain region PET activities based on either CT AC, two 3-class MRI AC techniques, or the proposed 4-class UTILE AC. Results: Using the UTILE MRI sequence, an acquisition time of 214 s was achieved for the head-and-neck region with 1.75-mm isotropic resolution, compared with 164 s for a single-echo UTE scan. MRI-based reciprocal sensitivity maps show a high correlation with those derived from CT scans (R2 5 0.9920). The same is true for PET activities (R2 5 0.9958). An overall voxel classification accuracy (compared with CT) of 81.1% was reached. Bone segmentation is inaccurate in complex regions such as the paranasal sinuses, but brain region activities in 48 regions across ± patients show a high correlation after MRI-based and CT-based correction (R2 5 0.9956), with a regression line slope of 0.960. All overall correlations are higher and brain region PET activities more accurate in terms of mean and maximum deviations for the 4-class technique than for 3-class techniques. Conclusion: The UTILE MRI sequence enables the generation of MRI-based 4-class m-maps without anatomic priors, yielding results more similar to CT-based results than can be obtained with 3-class segmentation only. Copyright © 2012 by the Society of Nuclear Medicine, Inc. Source

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