A model-based time-reversal of left ventricular motion improves cardiac motion analysis using tagged MRI data

<p>Abstract</p> <p>Background</p> <p>Myocardial motion is an important observable for the assessment of heart condition. Accurate estimates of ventricular (LV) wall motion are required for quantifying myocardial deformation and assessing local tissue function and viability. Harmonic Phase (HARP) analysis was developed for measuring regional LV motion using tagged magnetic resonance imaging (tMRI) data. With current computer-aided postprocessing tools including HARP analysis, large motions experienced by myocardial tissue are, however, often intractable to measure. This paper addresses this issue and provides a solution to make such measurements possible.</p> <p>Methods</p> <p>To improve the estimation performance of large cardiac motions while analyzing tMRI data sets, we propose a two-step solution. The first step involves constructing a model to describe average systolic motion of the LV wall within a subject group. The second step involves time-reversal of the model applied as a spatial coordinate transformation to digitally relax the contracted LV wall in the experimental data of a single subject to the beginning of systole. Cardiac tMRI scans were performed on four healthy rats and used for developing the forward LV model. Algorithms were implemented for preprocessing the tMRI data, optimizing the model parameters and performing the HARP analysis. Slices from the midventricular level were then analyzed for all systolic phases.</p> <p>Results</p> <p>The time-reversal operation derived from the LV model accounted for the bulk portion of the myocardial motion, which was the average motion experienced within the overall subject population. In analyzing the individual tMRI data sets, removing this average with the time-reversal operation left small magnitude residual motion unique to the case. This remaining residual portion of the motion was estimated robustly using the HARP analysis.</p> <p>Conclusion</p> <p>Utilizing a combination of the forward LV model and its time reversal improves the performance of motion estimation in evaluating the cardiac function.</p

High-resolution magnetic resonance imaging and diffusion tensor imaging of the porcine temporomandibular joint disc

This is the published version. Copyright © 2014 The British Institute of RadiologyObjectives: Diffusion tensor imaging (DTI) is an MRI modality for characterizing the property, microstructural organization and function in tissues such as the brain and spinal cord. Prior to this investigation, DTI had not been adapted for studies of the temporomandibular joint (TMJ) disc. Objectives were to test the feasibility of DTI to evaluate the porcine TMJ disc and to use DTI to observe differences in magnitude of anisotropy of water diffusion between TMJ disc regions. Methods: Five adult pig TMJs were scanned on a 9.4 Tesla horizontal bore MRI scanner using an inductively coupled surface coil. High-resolution gradient-echo and diffusion-weighted spin-echo based images were obtained. The mean diffusivity and fractional anisotropy (FA) were computed in different regions of the disc. Two observers were calibrated to review the two-dimensional and three-dimensional images. Polarized light microscopy was used as the gold standard for collagen fibre orientation. Results: In the sagittal plane, the mean diffusivity was higher in the posterior (1.28±0.10×10−3 mm−2 s−1) and anterior (1.27±0.08×10−3 mm−2 s−1) bands compared with the intermediate zone (0.96±0.01×10−3 mm−2 s−1), and the FA index was also lowest in the intermediate zone. In the coronal plane, the mean diffusivity was higher in the medial (1.42±0.01×10−3 mm−2 s−1) and lateral (1.21±0.12×10−3 mm−2 s−1) aspects than in the centre (1.09±0.08×10−3 mm−2 s−1), and the FA index was also lowest in the centre. Conclusions: DTI is a useful method for non-invasively characterizing the structure/property relationships of the porcine TMJ disc

A systems thinking approach to address sustainability challenges to the energy sector

The energy sector is an intrinsically dynamic and complex system, and therefore its behaviour is not solely controlled by constituent components. Rather, it is a consequence of dynamic interactions among them. To properly manage such a system in a sustainable manner, it is necessary to understand the underlying dynamics of component interactions. Despite this, the interconnections between components of the energy sector in research and policy have received little attention. Here, we outline crucial limitations of previous efforts and emphasize the importance of using systems thinking in addressing the energy sector's sustainability challenges. We demonstrate this by a case study of the Australian energy sector, which has experienced emerging sustainability issues. Research findings show that current policies promoting energy development in the country are likely to be ‘fixes that fail’ that ultimately undermine sustainability. To achieve in building a sustainable energy sector, the policy must focus on implementing long-term solutions and avoid short-term quick fixes

The deformation parameter is plotted against the systolic image numbers, which are directly proportional to the acquisition time in the systolic phase

The curves in the graph exhibits a nonlinear behavior.<p><b>Copyright information:</b></p><p>Taken from "A model-based time-reversal of left ventricular motion improves cardiac motion analysis using tagged MRI data"</p><p>http://www.biomedical-engineering-online.com/content/7/1/15</p><p>BioMedical Engineering OnLine 2008;7():15-15.</p><p>Published online 19 May 2008</p><p>PMCID:PMC2435113.</p><p></p

Displacement vectors (red lines) start from the selected points (blue dots) and project to the end points (green dots)

Please see the text for the detailed explanation of the figure.<p><b>Copyright information:</b></p><p>Taken from "A model-based time-reversal of left ventricular motion improves cardiac motion analysis using tagged MRI data"</p><p>http://www.biomedical-engineering-online.com/content/7/1/15</p><p>BioMedical Engineering OnLine 2008;7():15-15.</p><p>Published online 19 May 2008</p><p>PMCID:PMC2435113.</p><p></p

New generation of electrochemical immunoassay based on polymeric nanoparticles for early detection of breast cancer

Fouzi Mouffouk,1 Sihem Aouabdi,2 Entesar Al-Hetlani,1 Hacene Serrai,3 Tareq Alrefae,4 Liaohai Leo Chen5 1Department of Chemistry, Kuwait University, Safat, Kuwait; 2King Abdullah International Medical Research Center (KAIMRC), Jeddah, Kingdom of Saudi Arabia; 3Department of Radiology and Nuclear Medicine, University Hospital of Gent (UZG), Gent, Belgium; 4Department of Physics, Kuwait University, Safat, Kuwait; 5Surgical Precision Research&nbsp;Lab. Department of Surgery, University of Illinois at Chicago, IL,&nbsp;USA Abstract: Screening and early diagnosis are the key factors for the reduction of mortality rate and treatment cost of cancer. Therefore, sensitive and selective methods that can reveal the low abundance of cancer biomarkers in a biological sample are always desired. Here, we report the development of a novel electrochemical biosensor for early detection of breast cancer by using bioconjugated self-assembled pH-responsive polymeric micelles. The micelles were loaded with ferrocene molecules as &ldquo;tracers&rdquo; to specifically target cell surface-associated epithelial mucin (MUC1), a biomarker for breast and other solid carcinoma. The synthesis of target-specific, ferrocene-loaded polymeric micelles was confirmed, and the resulting sensor was capable of detecting the presence of MUC1 in a sample containing about 10 cells/mL. Such a high sensitivity was achieved by maximizing the loading capacity of ferrocene inside the polymeric micelles. Every single event of binding between the antibody and antigen was represented by the signal of hundreds of thousands of ferrocene molecules that were released from the polymeric micelles. This resulted in a significant increase in the intensity of the ferrocene signal detected by cyclic voltammetry. Keywords: electrochemical immunoassay, polymeric nanoparticles, breast cancer biomarkers, biosensors&nbsp

Thus magnitude of motion is considerably reduced between TR and Ithereby yielding a phase-wrap free HARP motion map

A mask is superimposed on the image frames to indicate the ROI.<p><b>Copyright information:</b></p><p>Taken from "A model-based time-reversal of left ventricular motion improves cardiac motion analysis using tagged MRI data"</p><p>http://www.biomedical-engineering-online.com/content/7/1/15</p><p>BioMedical Engineering OnLine 2008;7():15-15.</p><p>Published online 19 May 2008</p><p>PMCID:PMC2435113.</p><p></p

The operation () yields the deformed image in figure b, where the shape and size of the tag cells depict regional variations in motion

Similarly, a donut-shaped disk in figure c is used as a simple model of the left ventricle. Figure d shows the resulting deformed disk.<p><b>Copyright information:</b></p><p>Taken from "A model-based time-reversal of left ventricular motion improves cardiac motion analysis using tagged MRI data"</p><p>http://www.biomedical-engineering-online.com/content/7/1/15</p><p>BioMedical Engineering OnLine 2008;7():15-15.</p><p>Published online 19 May 2008</p><p>PMCID:PMC2435113.</p><p></p