In vivo visualization of cells labeled with superparamagnetic iron oxides by a sub-millisecond gradient echo sequence

Object: In vivo magnetic resonance imaging (MRI) of iron-labeled pancreatic islets (PIs) transplanted into the liver is still challenging in humans. The aim of this study was to develop and evaluate a double contrast method for the detection of PIs labeled with superparamagnetic iron oxide (SPIO) nanoparticles. Materials and methods: A double-echo three-dimensional (3D) spoiled gradient echo sequence was adapted to yield a sub-millisecond first echo time using variable echo times and highly asymmetric Cartesian readout. Positive contrast was achieved by conventional and relative image subtraction. Experiments for cell detection efficiency were performed in vitro on gelatin phantoms, in vivo on a Lewis rat and on a patient 6months after PI transplantation. Results: It was demonstrated that the proposed method can be used for the detection of transplanted PIs with positive contrast in vitro and in vivo. For all experiments, relative subtraction yielded comparable and in some cases better contrast than conventional subtraction. For the first time, positive contrast imaging of transplanted human PIs was performed in vivo in patients. Conclusion: The proposed method allows 3D data acquisition within a single breath-hold and yields enhanced contrast-to-noise ratios of transplanted SPIO labeled pancreatic islets relative to negative contrast images, therefore providing improved identification

Cardiovascular involvement in patients with Fabry disease

The evaluation of clinical magnetic resonance (MR) images is influenced by errors (subjective evaluation, noise, etc.). It is possible to eliminate these errors by using certain mathematical and statistical methods. One of these methods is texture analysis (TA), which can describe images quantitatively by computed texture parameters. The aim of this thesis was to analyze MR images of various subjects (phantoms, apples, calf muscles, livers) by TA and to evaluate its possible use in clinical practice. The main tasks of the thesis were: 1) to develop a new phantom suitable for TA and MR imaging that is biochemically and mechanically stable 2) to optimize an algorithm for TA parameter selection and classification 3) to apply TA in evaluating MR images. The first methodical part of the thesis deals with the optimization of texture parameter selection and texture classification. For this purpose a new type of phantom was developed. This PSAG phantom, with a nodular structure from polystyrene spheres (PS) placed into agar (AG), is suitable for MR imaging and for TA because it produces a strong MR signal and because its T1 and T2 relaxation times are in the range of biological tissue and can be easily modified by employing various densities of PS spheres or by the addition of a contrast agent. Measurements of PSAG..

Recent advances in metal–organic frameworks for applications in magnetic resonance imaging

Diagnostics is an important part of medical practice. The information required for diagnosis is typically collected by performing diagnostic tests, some of which include imaging. Magnetic resonance imaging (MRI) is one of the most widely used and effective imaging techniques. To improve the sensitivity and specificity of MRI, contrast agents are used. In this review, the usage of metal−organic frameworks (MOFs) and composite materials based on them as contrast agents for MRI is discussed. MOFs are crystalline porous coordination polymers. Due to their huge design variety and high density of metal ions, they have been studied as a highly promising class of materials for developing MRI contrast agents. This review highlights the most important studies and focuses on the progress of the field over the last five years. The materials are classified based on their design and structural properties into three groups: MRI-active MOFs, composite materials based on MOFs, and MRI-active compounds loaded in MOFs. Moreover, an overview of MOF-based materials for heteronuclear MRI including 129Xe and 19F MRI is given.HB acknowledges the support from the SPP 1928, COORNETs supported by the German Research Foundation. DJ acknowledges the support from the MH CR-DRO (Institute for Clinical and Experimental Medicine IKEM, IN00023001) and from the project National Institute for Research of Metabolic and Cardiovascular Diseases (Programme EXCELES, Project No. LX22NPO5104) funded by the European Union - Next Generation EU