Recommended implementation of arterial spin‐labeled perfusion MRI for clinical applications: A consensus of the ISMRM perfusion study group and the European consortium for ASL in dementia

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/109790/1/mrm25197.pd

Labeling of immune cells for in vivo monitoring of cell migration using magnetic resonance imaging and near-infrared imaging

In addition to macrophage localization, the opening of the blood brain barrier (BBB) as well as demyelination processes have been measured by MRI mapping gadolinium (Gd) related signal enhancement and magnetic transfer (MT), respectively. By successively applying this protocol at different time points during the EAE model progression, we were able to analyse the interdependence of immuno-cellular processes leading to axonal damage as well as the longitudinal evolution of pathological hallmarks of EAE. Furthermore, these techniques have been used to validate and quantify the anti-inflammatory effect of EDG-1 inhibitor FTY720 on EAE symptoms. Repeated USPIO administrations and MRI measurements combining the analysis of MT ratios and Gd-enhancement have been performed on vehicle and FTY720 treated animals. This study demonstrates that FTY720 can prevent inflammatory events in EAE rats by sequestrating immune cells in lymphoid organs during acute inflammation episodes. The third goal, was to translate the iron-labeling protocol from macrophages to T lymphocytes. As T-cells are initiators of the immune cascade leading to the occurence of symptoms in the EAE model, it would be highly relevant to visualize T lymphocytes prior to the onset of symptoms. Yet, as lymphocytes have no natural phagocytotic activity, in vivo tagging with CA was not feasible. We decided to label them in vitro with ferumoxides (FeO) and then, transfer iron-presenting cells adoptively to EAE animals intravenously. Different techniques have been used to evaluate the efficiency of lymphocytes labeling combining iron oxide particles with commonly available transfection agents (TAs) and the feasibility of labeling T lymphocytes in vitro has been demonstrated. However, the adoptive transfer of iron-tagged T-cells to EAE rats did not lead to the detection of these cells by MRI. As MR detection of iron-tagged cell in vivo was unsuccessful probably due to the inherent lack of sensitivity of the MRI technique for molecular changes and the dilution of labeled cells in the blood, we decided to switch to a more sensitive technique. Thus, the goal of the last part of the thesis was to label primary cultured T lymphocytes with a fluorescent dye: cyanine 5.5 (Cy5.5). The Tat peptide from the HIV virus chemically has been bound to the Cy5.5 to cargo the dye across T-cells membrane. The ability of this probe to penetrate T-cells and its potential toxicity has been evaluated in vitro. Subsequently, Cy5.5-Tat labeled lymphocytes were transferred to EAE rats in order to monitor their bio-distribution during EAE. Prominent signals have been obtained from rat brain and histological experimentation using confocal microscopy analysis have been performed to confirm the localization of Cy5.5 within the brain parenchyma

Medical imaging analysis with artificial neural networks

Given that neural networks have been widely reported in the research community of medical imaging, we provide a focused literature survey on recent neural network developments in computer-aided diagnosis, medical image segmentation and edge detection towards visual content analysis, and medical image registration for its pre-processing and post-processing, with the aims of increasing awareness of how neural networks can be applied to these areas and to provide a foundation for further research and practical development. Representative techniques and algorithms are explained in detail to provide inspiring examples illustrating: (i) how a known neural network with fixed structure and training procedure could be applied to resolve a medical imaging problem; (ii) how medical images could be analysed, processed, and characterised by neural networks; and (iii) how neural networks could be expanded further to resolve problems relevant to medical imaging. In the concluding section, a highlight of comparisons among many neural network applications is included to provide a global view on computational intelligence with neural networks in medical imaging

Acoustic Emission Measurement System in Diagnostic of Cartilage Injuries of the Knee

Abstract The measurement system BONEDIAS (Bone Diagnostic System) was developed as a non-invasive diagnostic method, based on the analysis on the acoustic emission from the knee joint. Knee squats of a patient will release acoustic emission in high temporal resolution and well correlated to the angle of knee flexion. The physician will get the relevant information concerning arthritic lesions in the knee joint (well characterized acoustic emission, singular events without a follow up of further emission), acoustic emission due to elevated intra-articular friction caused by e.g. cartilage lesions, inappropriate surface roughness, a lack of synovial fluid or crack initiation in the femur. Over 100 patients were analyzed with the measurement system BONEDIAS, afterwards the results were compared with the intra-operative views (arthroscopy and arthroplasty of the knee). Other parameters were studied, concerning the relation between the age and the sex of the subjects, the length of the femur, thigh thickness, the body mass index, the anatomical axis of the knee and the appearance and severity of the cartilage lesions. The study was made with the purpose to see if there was a correspondence between the cartilage disorders, the intraoperative views (arthroscopy and the arthroplasty of the knee) and the acoustic emission measurements, performed one day before the surgery. Because there arent at this moment cheap and standards methods who can determine the early cartilage injuries, this study is supposed (concording with the results) to open new ideas and new advantages in the diagnostic of this often disease, using the acoustic emission measurement system. The results obtained, 50% correspondence for the gr. 0, I and II Outerbridge lesions are more important, more significant that the other results, with over 60% correspondence for the advanced osteoarthrosis. The obtained acoustic emission signals, corresponding to the intra-arthroscopic findings showed the importance of this method to identify the early cartilage injuries. The method is not perfect and the results (50%) are not really statistically significant, so that we can introduce this method on a large scale, but offers important information that should be used in the future. Also, there isn’t a perfect method to compare the acoustic emission signals with the intra-arthroscopic findings. Every patient was analysed separately and with his corresponding measurement compared, that means a lot of time (20 – 30 minutes for the measurement and the other questions and clinical tests and another 15 minutes to analyse the signals and compare them with the intra-operative findings). For a study this can be accepted, but for clinical every day use maybe not. A standard interpretation and analyse method, maybe after clinical large trials, if such a method can be developed, could bring big advantages for the early determination of the cartilage injuries. In conclusion, the study had offered important informations about the importance of accoustic emission measurements, that can be used for the future studies and with some improvements, this method , cheap and non-invasive, but at this moment a little beat time-consuming, can be helpful in the diagnose of the early cartilage injuries

Echocardiography

The book "Echocardiography - New Techniques" brings worldwide contributions from highly acclaimed clinical and imaging science investigators, and representatives from academic medical centers. Each chapter is designed and written to be accessible to those with a basic knowledge of echocardiography. Additionally, the chapters are meant to be stimulating and educational to the experts and investigators in the field of echocardiography. This book is aimed primarily at cardiology fellows on their basic echocardiography rotation, fellows in general internal medicine, radiology and emergency medicine, and experts in the arena of echocardiography. Over the last few decades, the rate of technological advancements has developed dramatically, resulting in new techniques and improved echocardiographic imaging. The authors of this book focused on presenting the most advanced techniques useful in today's research and in daily clinical practice. These advanced techniques are utilized in the detection of different cardiac pathologies in patients, in contributing to their clinical decision, as well as follow-up and outcome predictions. In addition to the advanced techniques covered, this book expounds upon several special pathologies with respect to the functions of echocardiography