Traditional Posters : Pulse Sequences, Reconstruction & Analysis
Click on to view the abstract pdf and click on to view the pdf of the poster viewable in the poster hall.
G Pulse, Algorithms & Software Tools

Thursday May 12th
Exhibition Hall  13:30 - 15:30

2545.   Versatile higher-order reconstruction accelerated by a graphics processing unit (GPU)  
Michael Andreas Bieri1, Christoph Barmet1, Bertram Jakob Wilm1, and Klaas Paul Pruessmann1
1Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Zurich, Switzerland

FFT-based MR reconstruction algorithms get increasingly complex when incorporating various encoding terms such as static off-resonance, dynamic higher-order fields, coil sensitivity maps, non-Cartesian k-space sampling, etc. Therefore in this work a versatile algebraic reconstruction is employed that allows for incorporating various encoding mechanisms with only minor increase in complexity. A drawback is the enormous computing time even for small images. A 100x100 image needs minutes to be reconstructed on a current high end CPU. By implementing the algorithm on a graphics processing unit (GPU), speed-up of about 600x was achieved compared to a CPU. All result are shown at the example of dynamic higher order fields combined with static off-resonance and sensitivity encoding.

2546.   Accelerating Compressed Sensing MRI Reconstruction with GPU Computing 
David S Smith1,2, John C Gore1,2, and Edward Brian Welch1,2
1Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN, United States, 2Institute of Imaging Science, Vanderbilt University, Nashville, TN, United States

We show that compressed sensing MRI reconstruction using a Cartesian split Bregman solver can be dramatically accelerated using GPU computing. We find a factor of ~30 speedup for images of square dimension 512 and higher on a system based on an NVIDIA Tesla C2050 GPU card and Accelereye's Jacket GPU wrapper for MATLAB.

2547.   GPU-Accelerated Gridding for Rapid Reconstruction of Non-Cartesian MRI 
Nady M Obeid1, Ian C Atkinson2, Keith R Thulborn2, and Wen-Mei W Hwu1
1Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Champaign, IL, United States, 2Center for Magnetic Resonance Research, University of Illinois at Chicago, Chicago, IL, United States

In this work, we propose and elaborate on a method for accelerating gridding for the reconstruction of Non-Cartesian MRI using graphics processors (GPUs). Gridding interpolates the non-Cartesian input data onto a Cartesian grid as a preprocessing step to the FFT. We will explain the transformations needed to port the original CPU algorithm to the GPU, and how those transformation help improve performance. Our GPU-accelerated algorithm achieves up to 29X in runtime speedup for the gridding step, making fast reconstruction of non-Cartesian MR imaging data possible.

2548.   A GPU Implementation of Compressed Sensing Reconstruction of 3D Radial (Kooshball) Acquisition for High-Resolution Cardiac MRI 
Seunghoon Nam1,2, Tamer Ahmed Basha2, Mehmet Akçakaya2, Christian Stehning3, Warren J. Manning2, Vahid Tarokh1, and Reza Nezafat2
1SEAS, Harvard University, Cambridge, MA, United States, 2Dept. of Medicine (Cardiovascular Division), Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States,3Philips Research, Hamburg, Germany

Three dimensional radial (kooshball) trajectory allows high isotropic spatial resolution, better depiction of cardiac anatomy and ease of image prescription in whole heart cardiac MRI. While kooshball trajectory can provide significant reduction in acquisition time compared with 3D Cartesian sampling trajectories, its application has been limited due to high computational burden associated with the reconstruction process. In this abstract, we implement and evaluate an iterative compressed sensing reconstruction method for kooshball trajectory on Graphics Processing Units (GPU). The GPU implementation shows 58× faster reconstruction time compared with a sequential C++ implementation.

2549.   Implementation of Compressed Sensing for Online Reconstruction 
Cheng Ouyang1,2, Tobia Wech1,3, and Li Pan1,4
1Center for Applied Medical Imaging, Siemens Corporate Research, Baltimore, MD, United States, 2Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL, United States, 3Institute of Radiology, University of Wuerzburg, Wuerzburg, Bavaria, Germany, 4Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, MD, United States

Compressed sensing (CS) has been proposed as a technique to enable acquisition and reconstruction of images that are sparse or compressible with little to no loss of image quality. However, the existing work in the CS literature has been focused on offline reconstruction and simulation, partially due to the concern of the time-consuming steps of the sparsifying transform and non-linear iterative reconstruction. In this work, we demonstrated the feasibility of an online implementation of compressed sensing to achieve real-time image reconstruction on a clinical scanner. The performance of the TVCMRI algorithm used in the online implementation was effective in producing reconstructed images close to ground truth with rapid reconstruction speed.

2550.   Iterative Compressed Sensing Reconstruction for 3D Non-Cartesian Trajectories without Gridding & Regridding at Every Iteration 
Mehmet Akcakaya *1, Seunghoon Nam *1,2, Tamer Basha1, Vahid Tarokh2, Warren J. Manning1, and Reza Nezafat1
1Dept. of Medicine (Cardiovascular Division), Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States, 2School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, United States

3D non-Cartesian sampling trajectories allow high isotropic spatial resolution, better depiction of cardiac anatomy and ease of image prescription in cardiac MRI. Furthermore, undersampling with these trajectories causes incoherent artifacts that may be removed using compressed sensing (CS). CS reconstruction is typically done using conjugate-gradient (CG) type algorithms, which require gridding and regridding to be performed at every iteration. In this abstract, we investigate an alternative method for CS reconstruction that only requires two gridding and one regridding operation in total irrespective of the number of iterations.

2551.   Towards Computationally Efficient Autocalibration for Accelerated MRI using Compressed Sensing Parallel Imaging 
Anja Brau1, Peng Lai1, Srihari Narasimhan2, Babu Narayanan3, and Vijaya Saradhi2
1Global Applied Science Laboratory, GE Healthcare, Menlo Park, CA, United States, 2Computing & Decision Sciences Lab, GE Global Research, Bangalore, India, 3Medical Image Analysis Lab, GE Global Research, Bangalore, India

Computation of kernel weights as part of calibration in Compressed Sensing and Parallel Imaging algorithms like ESPIRiT and L1-SPIRiT is computationally expensive, especially for high channel count reconstructions. The weights are computed by obtaining a least squares fit for predicting target points in the calibration region using a set of source points in their neighborhood. The number of points in the neighborhood and their distance from the target point define quality of fit and computational complexity of the solver. We show that an optimally shaped neighborhood can give a significant improvement in the computational performance without sacrificing the image quality.

2552.   IceLuva: a scripting engine for fast development of reconstruction algorithms 
Francesco Santini1, Sunil Patil1,2, and Klaus Scheffler1
1Radiological Physics, University of Basel Hospital, Basel, Basel, Switzerland, 2Center for Applied Medical Imaging, Siemens Corporation, Corporate Research, Baltimore, MD, United States

Image postprocessing and analysis is often an important part of the image reconstruction process, especially in quantitative MR imaging. This step is usually performed in a research environment by exporting images to a separate desktop computer and using commercial software packages. In this work, we present a simplified framework based on an open source scripting engine (Lua) that integrates in the scanner reconstruction pipeline, and allows simple and fast deployment of postprocessing and analysis programs.

2553.   MeCS – Integrating prototype processing programs into clinical routine 
Berengar W Lehr1, Ferdinand Schweser1, Andreas Deistung1, Daniel Güllmar1, and Jürgen R Reichenbach1
1Medical Physics Group, Department of Diagnostic and Interventional Radiology I, Jena University Hospital, Jena, Germany

Prototype processing programs developed in research are mostly cumbersome to operate. Thus the way for a new processing method into clinical routine is long. The Medical Computation Server is an approach to integrate prototype processing programs into the existing clinical workflow. Providing a fast method to check if research promises are fulfilling clinical needs it indeed bridges the gap.

2554.   AGILE: An open source library for image reconstruction using graphics card hardware acceleration 
Florian Knoll1, Manuel Freiberger1, Kristian Bredies2, and Rudolf Stollberger1
1Institute of Medical Engineering, Graz University of Technology, Graz, Austria, 2Institute for Mathematics and Scientific Computing, University of Graz, Graz, Austria

Iterative image reconstruction of undersampled data from multiple coils has shown a huge potential for a wide range of applications during the last years. One of the main restrictions of these methods is the prolonged image reconstruction time. Parallelized implementations on graphics hardware were recently discovered as a feaseable method to significantly speedup image reconstruction. While programming graphics hardware was simplified significantly with the introduction of dedicated libraries for general purpose computing like CUDA or OpenCL, efficient implementation, especially concerning memory management, is still a challenging task. The goal of this work is to introduce an open source library designed for image reconstruction on GPUs. It is based on highly efficient implementations of numerical methods, but also includes code for iterative MR image reconstruction as well as a framework for finite element calculations and applications for Fluorescence Tomography. The results from this work illustrate the pronounced computational speedup with the GPU implementation. As the toolbox is an open-source project, all algorithms can be used either as a black box for the reconstruction of new data, or as a basis for own implementations for similar problems. The latter case is facilitated by the object-oriented and templated design which provides a well defined structure for extensions and allows for maximum code reusability. The intention behind the release of this open-source library is to alleviate the usage of the huge potential of graphics hardware in medical image reconstruction.

Traditional Posters : Pulse Sequences, Reconstruction & Analysis
Click on to view the abstract pdf and click on to view the pdf of the poster viewable in the poster hall.
Recent Advances in Image Analysis: Techniques

Monday May 9th
Exhibition Hall  14:00 - 16:00

2555.   A new high-dimensional machine learning approach for identifying Alzheimer Disease from MRI structural images 
Ramon Casanova1, Benjamin Wagner2, Christopher T. Whitlow2, Jeff D Williamson3, Sally A. Shumaker4, Joseph A. Maldjian2, and Mark A. Espeland1
1Biostatistical Sciences, Wake Forest University Baptist Medical Center, Winston-Salem, NC, United States, 2Radiology, Wake Forest University Baptist Medical Center, Winston-Salem, NC, United States, 3Geriatrics & Gerontology, Wake Forest University Baptist Medical Center, Winston-Salem, NC, United States, 4PHS, Wake Forest University Baptist Medical Center, Wisnton-Salem, NC, United States

Many classification methodologies for structural MRI (sMRI) images are based on a severe reduction of the feature space. Here we introduce a new classification method sMRI images, based on penalized logistic regression combined with a high dimensional image warping technique called ANTS that uses voxels as input features. We illustrate its performance when classifying images from a set of Alzheimer Disease Neuroimaging Initiative (ADNI) cognitive normal (CN) and Alzheimer Disease participants. Our methodology shows high levels of accuracy, sensitivity and specificity when automatically classifying sMRI images of CN subjects and AD patients.

2556.   Reduction of Amyloid Plaque FP Detections in MR images of the APP Transgenic Mouse Brain using Unsupervised SVM 
Gheorghe IORDANESCU1,2, Palamadai Venkatasubramanian1,2, and Alice Wyrwicz1,3
1Center for Basic MR Research, Northshore University HealthSystem, Evanston, Illinois, United States, 2Pritzker School of Medicine, University of Chicago, Chicago, Illinois, United States,3Biomedical Engineering, Northwestern University, Chicago, Illinois, United States

We present a novel method for amyloid plaques FP reduction in MR images. FP sources like vessels and brain region borders are modeled by multiscale features computed based on the square matrix of second-order partial derivatives and its eigenvalues. Our approach is novel since it does not require supervised training, and we did not follow the common approach of computing specific functions describing the “sheetness” or “lineness” of a catchment basin. Instead, we use the SVM flexibility of computing non-linear classification functions that can be used to detect FPs of specific shape. Our results show that our unsupervised algorithm is flexible and can be extended to reduce FP for plaque detection in MR images of AD mouse models, making our method suitable for the analysis of individual plaques and plaque distribution within different brain structures.

2557.   Universal Score of Structural Abnormality in Alzheimer's Disease 
Vitali Zagorodnov1, and O.V. Ramana Murphy1
1Nanyang Technological University, Singapore, NA, Singapore

Most recent solutions to diagnose Alzheimer’s disease (AD) from structural brain measurements have been based on pattern classification framework, where the classifier score is used as a measure of disease progression. However, new classifier score are typically have to be learned for each new application, i.e. classification of AD patients vs. normal controls, prediction of MCI conversion or cognitive test scores. We derive a single universal application-independent classifier, which performs similar to or better than existing solutions that have been individually optimized to each of these applications.

2558.   Discriminating Schizophrenia and Bipolar Disorder by Unique Patterns of Brain Function and Structure 
Jing Sui1, and Vince D. Calhoun2
1The Mind Research Network, Albuquerque, NM, United States, 2Dept. of ECE, University of New Mexico, Albuquerque, NM, United States

In this work, we highlighted both similarities and differences between 2 modalities across 3 diagnostic groups by fusion of fMRI and DTI data. We proposed a multimodal fusion method, ¡¯mCCA+jICA¡¯, which enabled more flexibilities in statistical assumptions. Most importantly, we are able to provide insights into the complex network between brain structure and function£¬which was not accessible from separate analysis of each modality. Our findings suggested although SZ and BP showed distinct brain patterns, they also shared common abnormalities in frontal brain mechanisms and in prefrontal thalamic white matter tracts, which may serve as potential illness biomarkers.

2559.   Semi-Automated Atlas-Based MRI Lung Volumetry 
Christina Rose Lurie1, Eduard Schreibmann2,3, James Robert Costello1, Puneet Sharma1, Hiroumi Kitajima1, Bobby Kalb1, Timothy Fox2,3, and Diego Raul Martin1
1Radiology, Emory University School of Medicine, Atlanta, GA, United States, 2Radiation Oncology, Emory University School of Medicine, Atlanta, GA, United States, 3Winship Cancer Institute of Emory University, Atlanta, GA, United States

Lung diseases are common and pulmonary function tests (PFT) serve as important measures of lung biomechanics, but PFT is limited to only indirect measures of combined lung volume changes. MRI may provide non-xray-based techniques to perform direct visualization of lungs with potential for multifaceted evaluation of pulmonary biomechanics, but is limited by prohibitive time-consuming data analysis post-processing steps. We have undertaken development of lung MRI image automated post-processing atlas-based lung segmentation and volumetry and show early validation steps by comparing MRI measures of lung volumes, performed in under 20 min, to PFT results with good correlation.

2560.   Semi-automatic segmentation of bony lesions from diffusion weighted MRI to assess disease burden and quantify response using Markov random fields 
Matthew David Blackledge1, Dow Mu Koh1, Anwar R Padhani2, James J Stirling2, N. Jane Taylor2, David J Collins1, and Martin O Leach1
1CR-UK and EPSRC Cancer Imaging Centre, Institute of Cancer Research and Royal Marsden Hospital, Sutton, Surrey, United Kingdom, 2Paul Strickland Scanner Centre, Mount Vernon Cancer Centre, Northwood, London, United Kingdom

A recent technique (DWIBS) employs fat suppressed whole-body diffusion weighted images for visual localization of metastases throughout the body. We provide a semi-automatic method for defining suspect regions in DWIBS data sets using Markov random field models and assess the utility of this technique for providing whole body tumour volume estimates.

2561.   Segmentation of Thalamus by Clustering of Resting-State fMRI 
Yi-Ping Chao1,2, Chun-Yi Lo3, and Ching-Po Lin4
1School of Applied Information Sciences, Chung Shan Medical University, Taichung, Taiwan, 2Department of Medical Imaging, Chung Shan Medical University Hospital, Taichung, Taiwan,3Department of Medical Imaging and Radiological Sciences, National Yang Ming University, Taipei, Taiwan, 4Institute of Neuroscience, National Yang Ming University, Taipei, Taiwan

In this study, we hypothesized that voxels belonging to the same partition of thalamus should be provided with the similar temporal cross-correlation values to other voxels. Therefore, we transferred the cross-correlation matrix derived from resting-state fMRI analysis to a meta-data for the data mining software to separate this data based on the k-median clusting algorithm. Finally, we presented the segmentations of thalamus according to the clustered results. From our results, resting-state fMRI could provide not only the functional connectivity network between cortical and subcortical brain regions, but also local characteristic within thalamus.

2562.   Multi atlas segmentation of rat leg muscles 
Michaël Sdika1, Anne Tonson1, Patrick J Cozzone1, and David Bendahan1
1CRMBM, CNRS, UMR 6612, Faculté de Médecinede Marseille, Université de la Méditérranée, Marseille, France

In this work we propose a fully-automated multi atlas segmentation method for the rat leg muscles (e.g., gastrocnemius and plantaris). Specific processing for this application are presented. The method is evaluated on an in vivo dataset.

2563.   Pattern Analysis and Magnetic Resonance Imaging in the study of Tumor Angiogenesis 
Marco Dominietto1, Steffi Lehmann1, Ruth Keist1, and Markus Rudin1
1Institute for Biomedical Engineering, ETHZ, Zurich, Switzerland

MRI allows the investigation of tumor angiogenesis-related parameters such as TBV, TBF, VSI and vascular permeability in-vivo. Tumor tissue is highly heterogeneous comprising areas with different degree of vascularization that cannot be studied with the conventional histogram procedure. Pattern analysis, which allow to estimate shape descriptors (as surface area, volume, compactness) and texture estimators (as fractal dimension and lacunarity) is able to invistigate such heterogeneity. The goal of this study is to apply the principles of pattern analysis to quantitatively assess angiogenesis/vascularity in a murine subcutaneous tumor model.

2564.   Combining parallel multiresolution and PCA initialization for a fully automatic PET-MRI registration 
Michaël Bernier1, Martin Lepage2, Roger Lecomte2, Luc Tremblay3, Louis Doré-Savard3, and Maxime Descoteaux4
1Département d'informatique et Centre d'imagerie moléculaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, QC, Canada, 2Centre d'imagerie moléculaire de Sherbrooke, Université de Sherbrooke, 3Centre d'imagerie moléculaire de Sherbrooke, Université de Sherbrooke, Canada, 4Computer Science, Université de Sherbrooke

Automatic and accurate image registration of PET-MRI images is not trivial, since the image intensity content of PET and MRI images is highly uncorrelated. Using normalized mutual information (NMI) and symmetric correlation ratio (SCR) as similarity measures in the registration algorithm, we propose 2 novel elements 1) we introduce a multi-resolution similarity measure combining the intensity histograms at 3 resolution levels simultaneously and 2) we add a PCA initialization to obtain a coarse initialization for a fast, fully automatic accurate registration. These novelties are highlighted for accurate automatic registration of 8 rats in a femur bone tumor study.

Maysa M Garcia Macedo1, Choukri Mekkaoui2, and Marcel Parolin Jackowski1
1Computer Science, University of São Paulo, São Paulo, SP, Brazil, 2Radiology, Harvard Medical School, Boston, MA, United States

Current techniques for the analysis of vascular networks are time-consuming and limited in their ability to assess the integrity and functional state of vascular architectures. In this work, we evaluate a novel technique based on the well-known Hough transform to dynamically estimate the trajectory and vessel diameter without resorting to time-consuming multiscale techniques. Results are validated using synthetic datasets and applied on a magnetic resonance angiography (MRA) image of a human brain. The proposed technique yielded high reproducibility rates, robustness to different noise levels, associated with simplicity of execution.

2566.   Novel MRI Sequence on 3T Accurately Depicts the Osseous Segments of Cranial Nerves VII-VIII: A Pilot Study 
Rivka R Colen1, Jr Yuan Chiou1, Yi Tang1, Thomas Lee1, and Ferenc A Jolesz1
1Radiology, Brigham and Women's Hospital, Boston, MA, United States

This novel 3D FSE Cube sequence incorporated with FLAIR and fat saturation for imaging of cranial nerves results in more accurate depiction and visualization of the osseous petrous portions of cranial nerves VII-VIII compared with conventional 3D CISS sequences. The ability to see these segments on a FLAIR sequences allows for not only clearer depiction and course but more importantly detection of subtle pathology which until now has been based on detection of changes in size on CT; thus, this sequence will allow for detection of changes in signal intensity affording earlier detection of pathological involvement previously unable to identify.

2567.   A motion tracking method applying spread spectrum communication to tagging MRI 
Yoshiaki Komori1, Akira Amano2, Keiko Maehara1, Jin Li1, Narazaki Michiko1, and Matsuda Tetsuya1
1Department of Systems Science, Graduate School of Informatics, Kyoto University, Kyoto, Japan, 2Department of Bioinformatics, College of Life Science, Ritsumeikan University, Kusatsu, Japan

We propose a new motion tracking method that encodes the position information of phantoms on a pixel-by-pixel basis by using tag patterns as digital codes. The experiments were conducted using stationary and moving phantoms. A segmented fast low angle shot cine sequence with SPAMM preparation pulses was used to encode the position information as 7-bit code words. This spread code was used to decode the position information. A spread spectrum communication technique was introduced into tagging MR images by regarding the tag patterns as digital codes. The position information of a moving phantom was successfully detected on a pixel-by-pixel basis.

2568.   3D Variography of Human White Matter and the Influence of Age 
Fabian Keil1, Ana Maria Oros-Peusquens1, and Nadim Jon Shah1,2
1Institute of Neuroscience and Medicine - 4, Forschungzentrum Juelich, Juelich, Germany, 2Department of Neurology, Faculty of Medicine, JARA, RWTH Aachen University, Aachen, Germany

Healthy human white matter (WM) shows hardly any contrast on MR images. One exception to this are frequently occurring hyperintensities (WMH) in T2 weighted acquisitions of elderly patients. In order to investigate structural changes in the WM before the manifestation as WMH, we propose a method for the statistical analysis of MRI data based on approaches known from geosciences. This method allows for the quantification of tissue homogeneity on various length scales. The results from 15 female volunteers showed significant correlations with age.

2569.   Dipolar Anisotropy Fiber Imaging of Human Anulus Fibrosus 
Won C Bae1, Sheronda Statum1, Richard Znamirowski1, Koichi Masuda2, Graeme M Bydder1, and Nikolaus M Szeverenyi1
1Radiology, University of California, San Diego, San Diego, CA, United States, 2Orthopaedic Surgery, University of California, San Diego, La Jolla, CA, United States

Anulus fibrosus (AF) forms concentric fibrous lamellae in the periphery of the intervertebral disc. AF is disrupted structurally during disc herniation and degeneration, but is not routinely visualized with clinical MR imaging. In this study, a degenerate human disc specimen was imaged using 3D FSPGR in six orientations, co-registered, and image-processed to visualize detailed fiber structure of the AF. Classic lamellar patterns of the AF, only previously observed with light microscopy, were observed, along with signs of degeneration such as thickening and inverse bulging of the lamellae. This technique can be implemented in vertical magnets for clinical use.

2570.   Robust Edge-directed MRI interpolation 
Zhenhua Mai1, Wolfgang Jacquet1, Marleen Verhoye2, and Jan Sijbers1
1Physics Department, Universiteit Antwerpen, Wilrijk, Antwerpen, Belgium, 2Biomedical Department, Universiteit Antwerpen

A novel edge-directed MRI interpolation framework that is robust against noise is introduced in this work, which benefits from a robust least squares pattern estimation as well as a Non-local Mean weighting scheme. It is shown to produce better results than conventional interpolation methods.

2571.   Correlation of Magnetic Susceptibility with Structural Characteristics in White Matter Regions of the Central Nervous System 
Cynthia Wisnieff1, Tian Liu1, Krishna Surapaneni, MD, MPH2, Craig I. Horenstein, MD2, and Yi Wang1,3
1Biomedical Engineering, Cornell University, Ithaca, New York, United States, 2Department of Radiology, Columbia University, New York, NY, United States, 3Radiology, Weill Cornell Medical College, New York, NY, United States

Quantitative susceptibility mapping (QSM) of the brain is quantitative assessment of tissue magnetic properties and recent observations have shown that the observed susceptibility in the brain may have an additional structural orientation dependency. This is especially important in the white matter of the central nervous system(CNS) where diffusion tensor imaging(DTI) has shown highly ordered structures with varying orientations to the B0 magnetic field. This study compares fiber orientations derived from DTI in white matter regions and correlates these structural measures with QSM to show significant correlations between the fiber orientation and the QSM value of white matter tracts. Further studies into the composition and orientation are required to better understand the observed correlation.

2572.   Intra-Voxel Linear Spectral Mixture Analysis Method for Tissues Quantification in Brain MRI 
Hsian-Min Chen1, Englin Wong2, Clayton Chi-Chang Chen3, Jyh-Wen Chai3, Shih-Yu Chen4, Ching-Wen Yang5, San-Kan Lee3, and Chein-I Chang2
1Department of Biomedical Engineering, HungKuang University, Taichung, Taiwan, 2Department of Computer Science and Electrical Engineering, University of Maryland, Baltimore, United States,3Department of Radiology, Taichung Veterans General Hospital, Taichung, Taiwan, 4Department of Electrical Engineering, National Chung Hsing University, Taichung, Taiwan, 5Computer Center, Taichung Veterans General Hospital, Taichung, Taiwan

This paper develops an intra-voxel multispectral approach for brain MRI to estimating abundance fractions of tissue substances present in a voxel of an image slice. The idea is originated from remote sensing image processing by using LSMA method to estimate the abundance fraction of a particular tissue substance. The 3D ROC analysis is also developed for performance evaluation where a third dimension is introduced to threshold abundance fractions so as to detection rates. The experimental results demonstrate the utility of the intra-voxel multispectral techniques to compute partial volumes of each of tissue substances via their estimated abundance fractions.

2573.   Iron, Ferritin, Myelin, and MR-Contrast: Proton-Induced X-Ray Emission (PIXE) Maps of Cortical Iron Content 
Carsten Stueber1, Markus Morawski2, Katja Reimann1, Nirav Barapatre3, Stefan Geyer1, and Robert Turner1
1Department of Neurophysics, Max-Planck-Institute for Human Cognitive and Brain Sciences, Leipzig, Germany, 2Paul-Flechsig-Institute of Brain Research, University of Leipzig, Germany, 3LIPSION Laboratory, Institute of Nuclear Solid State Physics, University of Leipzig, Germany

MR imaging at ultra-high field strengths has tremendously improved the visualization of human brain structures in recent years. In particular, strong differences in contrast are seen within the cerebral cortex that apparently reflect local myeloarchitecture. There is an ongoing controversy regarding the relative importance of iron in myelinated tissue, as a partly independent source of tissue contrast. We used a new powerful technique, the so-called Proton-Induced X-Ray Emission (PIXE), which provides a gold standard for mapping the intracortical iron content and could show that conventional staining methods do not adequately reflect the true iron distribution.

2574.   Automatic determination of arterial input function for estimating tumor microvessel density with dynamic contrast-enhanced MRI in mice model 
Jae-Hun Kim1, Geun-Ho Im2, Jehoon Yang1, and Jung Hee Lee1
1Department of Radiology, Samsung Medical Center, Seoul, Gang-Name, Korea, Republic of, 2Center for Molecular and Cellular Imaging, Samsung Biomedical Research Institute, Samsung Medical Center, Seoul, Korea, Republic of

Converging evidences have indicated that dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) provides parameters indicating permeability of tumor microvessels which has been shown to be closely related to angiogenesis. For quantification of DCE-MRI, determination of arterial input function (AIF) is required. However, a manual determination of AIF in MR images of a mouse is often difficult due to small spatial resolution or the location of the tumor. In this study, we propose an algorithm for automatic determination of AIF from mouse DCE-MRI data using clustering analysis (Kendall¡¯s coefficient of concordance). Our results showed that permeability parameters computed from our method were comparable with those from the manual determination of AIF in Ktrans (8.85 ¡¾ 9.49 %), ve (4.65 ¡¾ 2.34 %), and kep (11.72 ¡¾ 6.70 %), except for vp (98.37 ¡¾ 739.11 %). These findings show the feasibility of an automatic determination of AIF in the mouse data using KCC measurement.

Traditional Posters : Pulse Sequences, Reconstruction & Analysis
Click on to view the abstract pdf and click on to view the pdf of the poster viewable in the poster hall.
Recent Advances in Image Analysis: Applications

Tuesday May 10th
Exhibition Hall  13:30 - 15:30

2575.   Novel methods for assessing the composition of colonic contents in a model of diarrhoea 
Elisa Placidi1, Antonio Napolitano2, Caroline L Hoad1, Luca Marciani3, Klara C Garsed3, Robin C Spiller3, and Penny A Gowland1
1SPMMRC, University of Nottingham, Nottingham, United Kingdom, 2Academic Radiology, QMC, Nottingham, United Kingdom, 3Nottingham Digestive Diseases Centre Biomedical Research Unit, Nottingham, United Kingdom

This abstract presents the development and the comparison of two automated operator-independent methods for the objective classification of the AC contents, based on previously optimised MRI techniques to study the gastrointestinal tract. A Gaussian fit of the histogram of the ROI and a texture analysis based on Gabor wavelet are compared: the first one results very time consuming while the second one is very quick and in accordance with the experimental results and it could be used in future studies for assessing the effectiveness of a range of agents designed to treat diarrhoeal diseases.

2576.   Creating a one-stop shop? 3D black blood vessel wall imaging would combine information of luminal severity and plaque composition 
Li Dong1, Hao Shen2, Xiaojie Zhang1, Wei Yu1, Zhaoqi Zhang1, Hua Guo3, Ren Wang1, Dongxu Lu1, and Chun Yuan3,4
1Capital Medical University, Beijing Anzhen Hospital, Beijing, Beijing, China, People's Republic of, 2GE Healthcare, 3School of Medicine, Tsinghua University, 4University of Washington

We hypothesized that 3D black blood, a single sequence, can quantify carotid stenosis and plaque composition simultaneously. Bilateral carotid arteries from 9 symptomatic subjects underwent 3D SPGR and MRA scans. There was an excellent correlation of measuring stenosis between 3D SPGR and MRA (r = 0.95, p < 0.001). For those arteries with corresponding histology (n = 5), good agreements in identifying major plaque components were found. Therefore, 3D black blood images allow interactive reconstruction in arbitrary planes providing a more thorough visualization of luminal severity and plaque components.

2577.   Multi-modal MRI analysis for automatic trajectory planning of deep brain stimulation neurosurgery 
Silvain Bériault1, Fahd Al Subaie2, Kelvin Mok3, Abbas F Sadikot2, and G Bruce Pike1
1McConnell Brain Imaging Centre, Montreal Neurological Institute, Montréal, Québec, Canada, 2Department of Neurology and Neurosurgery, Montreal Neurological Institute, 3Neuronavigation Unit, Montreal Neurological Institute

We propose an automated method for preoperative trajectory planning of deep brain stimulation image-guided neurosurgery. Our framework integrates multi-modal MRI analysis (T1w, SWI, TOF-MRA) to determine an optimal trajectory to the subthalamic nuclei while avoiding critical brain structures for prevention of hemorrhages, loss of function and other complications. Results show that our automatic method aggregates several surgical requirements into a meaningful trajectory ranking, providing neurosurgeons with an intuitive decision-support system intended to improve standard (manual) planning techniques offered by commercial neuronavigation platforms. Our method analyzes over 12,000 trajectories in less than 4 minutes.

2578.   Investigating the role of choroid plexus in CSF pulsation by combining in-vivo and post-mortem MRI 
Simone Bottan1, Andri Fritz1, Vartan Kurtcuoglu1, Marianne Schmid Daners2, Verena Knobloch3, Christian Langkammer4,5, Nikolaus Krebs5, monika Gloor6, Eva Scheurer5, Klaus Scheffler4, Stefan Ropele4, Peter Boesiger3, Dimos Poulikakos1, and Michaela Soellinger4
1Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering, ETH Zurich, Zurich, Zurich, Switzerland, 2Institute for Dynamic Systems and Control, ETH Zurich, Zurich, Switzerland, 3Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland, 4Department of Neurology, Medical University of Graz, Graz, Austria, 5Ludwig Boltzmann Institute for Clinical-Forensic Imaging, Graz, Austria, 6Department of Radiology, University Hospital Basel, Basel, Switzerland

Cerebrospinal fluid (CSF) shows pulsating dynamics, due to the transmission of the cardiac pulse pressure wave to the ventricular system. The exact description of this transmission is still debated in the scientific community. Several studies have shown choroid plexus (CP) to play an important role to establish CSF dynamics. In the presented study, we evaluated volumes of CP by post-mortem bSSFP MRI and compared them to in-vivo CSF flow measurements. Our results showed a very small volumetric deformation of CP to be necessary to induce in-vivo CSF strokes in the cerebral aqueduct.

2579.   A Reproducibility Study in PAD Patient Plaque Burden Analysis Approach with Multi-Contrast Weighting MRI 
Dongxiang Xu1, Aaron Black2, Yihua Liao2, Timothy Carroll2, Debiao Li2, James Carr2, Chun Yuan3, and Mary M McDermott2
1Radiology, University of Washington, Seattle, WA, United States, 2Northwestern University, 3University of Washington

In a long term, large PAD clinical trial, the reproducibility of MRI based plaque burden evaluation is very important to the success of study. To evaluate the reliability of multi contrast MR imaging technique on femoral artery, two variability studies on a subset of trial data were conducted. The statistical analysis on quantitative plaque measurements demonstrated that reproducibility of MR imaging is satisfactory in PAD study. Using this technique can also help reduce the Inter-Reader variability in follow up plaque analysis. This means that current techniques used in MR imaging and plaque burden analysis can provide effective and reliable quantitative measurements for peripheral arterial disease evaluation.

2580.   ICA analysis of brachial plexus injury in an animal model reveals rapid brain plasticity in 9.4 T 
Rupeng Li1, J,B, Stephenson IV2, Christopher Pawela3, Ji-Geng Yan2, Andrew Nencka3, Anthony G Hudetz4, Hani Matloub2, and James S Hyde1
1Biophysics, Medical College of Wisconsin, Milwaukee, WI, United States, 2Plastic Surgery, Medical College of Wisconsin, 3Biophysics, Medical College of Wisconsin, 4Anesthesiology, Medical College of Wisconsin

We demonstrated that ICA can be used to show the somatosensory network in rat brain. This network is symmetrical in both hemispheres across the S1 area in healthy animals. Following brachial plexus avulsion injury, this network was disrupted. The somatosensory network on the injuried side switched from a synergic functional network to an anti-correlated network, which, we believe, is related to inhibitory neuronal activity.

2581.   Artificial hematomas in subcutaneous fatty tissue: volume estimation by using different MR sequences and manual segmentation of pork belly phantoms 
Kathrin Ogris1,2, Martin Urschler1,3, Andreas Petrovic1,4, Kathrin Yen1,5, and Eva Scheurer1,5
1Ludwig Boltzmann Institute for Clinical- Forensic Imaging, Graz, Austria, 2Department of Forensic Medicine, Medical University, Graz, Austria, 3Institute for Computer Graphics and Vision, University of Technology, Graz, Austria, 4Institute of Medical Engineering, University of Technology, Graz, Austria, 5Medical University, Graz, Austria

While the detection of hemorrhage in clinical medicine is focused on organs and body cavities forensic imaging requires reliable localization and analysis of hematomas in soft tissues such as the subcutaneous fatty tissue for the reconstruction of events. To evaluate different MRI sequences with respect to their ability of showing high contrast between hematoma and fatty tissue pork phantoms were examined after injection of small blood volumes, and the reproducibility of volume estimation by manual segmentation was assessed. A TSE T1T2w sequence yielded the best results for volume estimation of hematoma in fatty tissue. Reproducibility of the measurements was excellent.

2582.   Automatic detection of cortical thickness measurement errors using Support Vector Regression 
Vitali Zagorodnov1, and Kallam Hanimi Reddy2
1Nanyang Technological University, Singapore, NA, Singapore, 2Nanyang Technological University

Despite steady improvements in automated brain structural measurement algorithms (FreeSurfer, VBM, CLASP) over recent years, segmentation errors still frequently occur and require tedious manual review and editing of the segmentation results. We propose a framework based on Support Vector Regression to automatically highlight the errors in cortical thickness measurements, obtained using FreeSurfer segmentation pipeline. Our approach exploits high correlations between regional cortical thicknesses , which allows “guessing” what the correct measurement should be for a specific region, based on the rest of the brain measurements.

2583.   The simultaneous multiple-voxel processing of MRI data using Bayesian random effects modelling 
Martin David King1, Fernando Calamante2, Chris A Clark1, and David Gadian1
1Institute of Child Health, University College London, London, United Kingdom, 2Brain Research Institute, Melbourne, Australia

A common feature of many MRI data analyses in an independent, voxel-by-voxel treatment. In many applications this is expected to be inefficient in its use of the data, and improved parameter estimates should be attainable by adopting a statistical model in which image voxels are modelled as belonging to a population with an underlying statistical distribution. Among the methods that are well documented in the statistics literature is Bayesian spatial random effects modelling, implemented using Markov chain Monte Carlo. In this work we use dynamic susceptibility contrast data to illustrate the strengths of the Bayesian random effects modelling approach.

2584.   Automatic brain tumor segmentation and tumor tissue classification based on multiple MR protocols 
Astrid Franz1, Henriette Tschampa2, Andreas Müller2, Stefanie Remmele1, Jochen Keupp1, Jürgen Gieseke3, Hans Heinz Schild2, and Petra Mürtz2
1Philips Research, Hamburg, Germany, 2Department of Radiology, University Hospital Bonn, Bonn, Germany, 3Philips Healthcare, Hamburg, Germany

We present a nearly automatic segmentation and classification algorithm for human brain tumor tissue working on a combination of magnetic resonance T1 weighted contrast enhanced images and FLAIR images, based on a simple region growing technique. Algorithmic parameters are adapted automatically in the course of growing. The only required user interaction is a mouse click for providing the starting point. The algorithm is robust, i.e. independent of the given starting point within the tumor, and avoids leakage. We validated the algorithm on 20 test cases of human glioblastoma and meningioma. In 85% of the test cases we got satisfactory results.

2585.   Surface Morphometry of Subcortical Structures in Premature Neonates 
Yalin Wang1, Ashok Panigrahy2,3, Rafael Ceschin2, Songling Liu1, Paul M Thompson4, and Natasha Leporé3
1Computer Science and Engineering, Arizona State University, Tempe, AZ, United States, 2Radiology, Children's Hospital of Pittsburgh of UPMC, Pittsburgh, PA, United States, 3Radiology, Childrens Hospital Los Angeles, Los Angeles, CA, United States, 4Laboratory of Neuro Imaging, UCLA School of Medicine, Los Angeles, CA, United States

Changes in surface morphometry of the corpus callosum and lateral ventricles are likely sensitive indicators of diffuse white matter injury and of the interrelated subcortical grey matter injury in preterm neonate. Using brain structural magnetic resonance (MR) images, we propose a novel pipeline for regional group comparisons of the surface anatomy of subcortical structures in neonates. We study a total of 7 brain subcortical structures: the corpus collosum, lateral ventricle, thalamus, hippocampus, caudate nucleus, putamen and the 3rd ventricle. Our analysis will be applied to compare MR data of premature neonates to those of healthy term born neonatal controls.

2586.   Preliminary results on the clinical relevance of multiple sclerosis lesion distribution independent of lesion volume 
Fahime Sheikhzadeh1,2, and Roger Tam2,3
1Biomedical Engineering Program, University of British Columbia, Vancouver, BC, Canada, 2MS/MRI Research Group, University of British Columbia, Vancouver, BC, Canada, 3Department of Radiology, University of British Columbia, Vancouver, BC, Canada

Most studies on multiple sclerosis (MS) lesions focus on correlation between lesion volume and clinical measures, such as the Expanded Disability Status Scale (EDSS). This preliminary study investigates the contribution of the spatial distribution of lesions to disability. The white matter lesions on the T2w and PDw MRIs of 24 MS patients were delineated and the 3D spatial distribution of the lesion voxels in each patient was computed using the variance of Euclidean distances from a fixed reference point. Correlation and linear regression analysis show that lesion distribution contributes independently to EDSS and is potentially more sensitive than lesion volume.

2587.   Improved susceptibility quantification with effective magnetic moment 
Saifeng Liu1, Jaladhar Neelavalli2, Jin Tang1, and Ewart Mark Haacke2,3
1School of Biomedical Engineering, McMaster University, Hamilton, Ontario, Canada, 2The Magnetic Resonance Imaging Institute for Biomedical Research, Detroit, Michigan, United States,3Academic Radiology, Wayne State University, Detroit, Michigan, United States

Susceptibility quantification for small objects was improved by considering the effective magnetic moment. We proved that the product of measured susceptibility and the apparent volume stays constantly at different echo times, and showed that susceptibility quantification for small objects is limited by error in volume estimation.

2588.   Automated Volumetric Measurements of Posterior Cranial Fossa by MRI: Applications to Chiari I Malformation 
Noam Alperin1, Snag Lee1, Derek Monette1, Ahmet Bagci1, Birgit Ertl-Wagner2, and Raymond Sekula3
1University of Miami, Miami, FL, United States, 2University of Munich, Germany, 3Allegheny General Hospital, Pittsburgh

The diagnosis of Chiari Malformations type I (CMI) is based on tonsillar herniation of 5 mm or more below foreman magnum. However, this criterion is poorly correlated with symptoms severity or outcome. The size of the posterior cranial fossa (PCF) has been shown to be a more sensitive marker for CMI. Currently there is no reliable method for volumetric assessment of the PCF. An automated method for measurements of PCF and hindbrain tissue volumes has been developed and applied to CMI. Results demonstrate, for the first time, that in addition to smaller PCF, CMI is also associated with a smaller 4th ventricle.

2589.   Atrophy in rats induced with mild TBI and hemorrhagic shock: A TBM-based analysis 
Priya Goel1, Sushmita Datta1, Kurt H Bockhorst1, Jovany C Navarro2, Claudia S Robertson2, and Ponnada A Narayana1
1Diagnostic and Interventional Imaging, Medical School, The University of Texas Health Science Center at Houston, Houston, TX, United States, 2Neurosurgery, Baylor College of Medicine, Houston, TX, United States

In this study, we investigated the regional volume changes in brain caused by mild traumatic brain injury with hemorrhagic shock in rat models using tensor-based morphometry (TBM) that has methodological advantages over the commonly used voxel-based morphometric (VBM) techniques. Our analysis resulted in the detection of atrophy at the site of injury and some deep gray matter structures such as amygdala and suprachiasmatic nucleus which might perhaps explain the various post-traumatic disorders that the mTBI victims suffer.

2590.   Perceived dark rim in first-pass myocardial perfusion MRI due to visual illusion 
Taehoon Shin1, Bosco S Tjan2, and Krishna S Nayak3
1Electrical Engineering, Stanford University, Stanford, CA, United States, 2Psychology and Neuroscience, University of Southern California, Los Angeles, CA, United States, 3Electrical Engineering, University of Southern California, Los Angeles, CA, United States

First-pass cardiac perfusion MRI often suffers from artifactual sub-endocardial dark rim that lowers diagnostic specificity and limits its routine clinical use. Insufficient spatial resolution and motion during data acquisition have been identified as potential causes of dark rim artifact (DRA). This study uncovers a new potential source of perceived DRA that is rooted in human visual illusion. We demonstrate that DRA can be perceived solely due to visual illusion in the absence of any true signal dip, using numerical phantoms and in-vivo perfusion images.

2591.   Quantitative description of vessel geometry from microscopic MR skin imaging 
Elmar Laistler1, and Ewald Moser1
1MR Center of Excellence, Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria

We present a technique to obtain quantitative parameters describing the geometry of the cutaneous vessel tree. Data is obtained from MR microscopy of the human skin in vivo by transforming the segmented vessel data into a graph. The technique might help in diagnosis of vascular inflammation or malformation and can be used for treatment monitoring due to its non-invasiveness.

2592.   In Vivo MR Quantification of Liver Fat Content in Obese Mice: Comparison of Dual-Echo Dixon Imaging, Chemical Shift Selective Imaging and Hydrogen MR Spectroscopy 
Shenghong Ju1, and Xin-Gui Peng1
1Department of Radiology, Zhongda Hospital, Southeast University, Nanjing, Jiangsu, China, People's Republic of

T1WI can be used to measure liver volume and observe fat distribution; IP-OP method gives a FC that is significantly lower than the actual value, especially in higher fat concentrations; CSI and 1H MRS are accurate in quantifying fat in both phantoms and liver in vivo. Given their excellent correlation and concordance with LL analysis, CSI and MRS may replace liver fat histological and chemical analysis in longitudinal studies.

2593.   MR Multiparametric Analysis for Tumour Heterogeneity Characterisation. Framework & Initial Experiment in Liver Metastases. 
Rado Andriantsimiavona1, Martin Leach1, Simon Doran1, David Collins1, Soeren Grimm2, and Dow-Mu Koh1
1Institute of Cancer Research UK, Sutton, Surrey, United Kingdom, 2Biotronics3D Ltd., London, United Kingdom

Tissue characterisation based on multiparametric MR imaging data can be harnessed to evaluate tumour heterogeneity and their response to conventional and novel therapies. Unfortunately, no framework and application enables these complex datasets to be displayed and correlated with each other. We have built a functional imaging framework to link analysis of multimodality and multiparametric data, explore and characterise tumoural tissues types. We introduced a 3-class fuzzy classification / ternary bit combination merging method to segment tumour and identify heterogeneous tumoural areas. We applied the method to clinical trial liver metastases dataset and automatically identified necrosis among other tumoural tissue subtypes.

2594.   Computation of Structure Model Index in the Spatial Resolution Regime of in vivo Trabecular Bone MRI 
Shing Chun Benny Lam1, Jeremy F. Magland1, Scott N. Hwang2, and Felix W. Wehrli1
1Radiology, University of Pennsylvania, Philadelphia, PA, United States, 2Radiology, Emory University, Atlanta, GA, United States

The structure model index (SMI) is a metric characterizing the structure type (plate versus rod) of a trabecular bone network. However, application of SMI to in vivo MRI has been limited by spatial resolution. Here, we explored two up-sampling methods, sinc-interpolation and subvoxel processing, to enable computation of SMI from in vivo MRI. Comparison with values derived from CTimages (regarded as ground truth) showed SMI values obtained from subvoxel processed images to be closer to ground truth than those derived from sinc-interpolated images in terms of correlation coefficients and root mean square differences. Finally, subvoxel processed images were less sensitive to variations in binarization threshold.

2595.   Targeted coregistration of abdominal DCE MRI 
Artem Mikheev1, Vivian S Lee1, and Henry Rusinek1
1Radiology, NYU School of Medicine, New York, NY, United States

Simple coregistration algorithms do not work well for DCE images because of the change in intensity due to the uptake and washout of contrast agent. We have implemented several coregistration algorithms and tested them in the setting of functional exams of the kidney. The variants differ in sequencing of coregistration steps and in the way the organ of interest is specified. Serial and full 4D modes were found to be more accurate than radial mode. There was no statistically significant advantage of full 4D over serial modes. The execution times ranged 16-25 sec for serial, 14-16 sec for radial, and 61-73 sec for full 4D. Targeted coregistration of time series data appears to be reliable and ready for clinical use.

2596.   Automatic registration of renal perfusion image sequences by mutual information and adaptive prediction 
Vincenzo Positano1, Ilaria Bernardeschi1, Virna Zampa2, Martina Marinelli3, Maria Filomena Santarelli3, and Luigi Landini1,4
1MRI Lab, Fondazione G.Monasterio CNR-Regione Toscana, Pisa, Italy, 2Department of Diagnostic and Interventional Radiology, University of Pisa, Pisa, Italy, 3Institute of Clinical Physiology, Pisa, Italy, 4Department of Information Engineering, University of Pisa, Pisa, Italy

The aim of the study is to develop an automatic image registration technique able to compensate kidney motion in renal perfusion studies. The developed method is able to compensate kidney motion with a precision not significantly different from inter-observer variability of human operators.

2597.   Automated Analysis of MRI Data of Patients with ADPKD for the Volume of the Kidneys and of the Enclosed Cysts 
Stathis Hadjidemetriou1, Wilfried Reichardt1, Juergen Hennig1, and Martin Buechert2
1Department of Diagnostic Radiology, Medical Physics, University Medical Center Freiburg, Freiburg, Germany, 2MRDAC, University Medical Center Freiburg, Freiburg, Germany

Autosomal dominant polycystic kidney disease (ADPKD) is a genetic condition in which growing cysts disrupt the parenchyma and increase the total kidney volume. It eventually leads to kidney failure and no treatment for it is yet available. However, clinical treatment trials are performed monitored with MRI. It has been shown that imaging biomarkers extracted from MRI data can be used as surrogate markers for the progression and treatment of the condition. A method is presented for the automated extraction of the biomarkers from the images that can accelerate the trials and improve the objectivity of the results.

2598.   Automatic Mean Transit Time Lesion Outlining in Acute Stroke Using Level Sets 
Kim Mouridsen1, Anders Neumann2, Lars Riisgaard Ribe3, Kristjana Yr Jonsdottir3, and Leif Østergaard3
1Center for Functionally Integrative Neuroscience, Aarhus University Hospital, Aarhus University, Aarhus, Denmark, 2Aarhus University Hospital, 3Center for Functionally Integrative Neuroscience, Aarhus University Hospital, Aarhus University

The mismatch volume between perfusion weighted- and diffusion weighted imaging is an emerging target for thrombolytic therapy in clinical management and clinical trials. However, the critical delineation of the perfusion lesion boundary suffers extreme interobserver variability, due to diffuse gradients between normal and ischemic tissue. We propose estimating the perfusion lesion by finding a smooth contour, which minimizes variation around a patient-specific elevated MTT value inside the contour, and variation around a normal value outside the lesion, using variational calculus. We show that, in contrast to simple thresholding, this technique compares excellently with lesion outlines by four expert neuroradiologists

2599.   Effect of ISODATA Dimensionality on Spatiotemporal Evolution of Ischemic Brain Injury in Acute Ischemic Stroke 
Jerry S. Cheung1, Enfeng Wang1,2, Xiaoying Wang3, and Phillip Zhe Sun1
1Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, MGH and Harvard Medical School, Charlestown, MA 02129, United States, 2Department of Radiology, 3rd Affiliated Hospital, Zhengzhou University, China, People's Republic of, 3Neuroprotection Research Laboratory, Department of Radiology and Neurology, MGH and Harvard Medical School, Charlestown, MA 02129, United States

Iterative self-organizing data analysis technique algorithm (ISODATA) has been increasingly used to classify multi-parametric data for delineation of heterogeneous ischemic damage. Our study compared two different dimensionalities (1D vs. 2D) of ISODATA signature vector in ISODATA parameter space to segment evolving PWI/DWI mismatch. We showed that accurate delineation of PWI/DWI mismatch with 1D signature vector outperformed conventional 2D analysis, and offer a useful means to identify ischemic penumbra.

2600.   How shaky is MRE? Bootstrap and Monte Carlo Analysis of Reliability 
Geng Guangqiang1, Lynne Bilston1,2, Ralph Sinkus3, Roland Henry4, and Caroline Rae1,5
1Neuroscience Research Australia, Sydney, NSW, Australia, 2Prince of Wales Clinical School, UNSW, Sydney, Australia, 3Centre de Recherches Biomédicales Bichat-Beaujon, Paris, France,4Departments of Radiology and Biomedical Imaging, Neurology, and Bioengineering Graduate Group, University of California, San Francisco, United States, 5UNSW, Syndey, Australia

Magnetic resonance elastography (MRE) measures the mechanical properties of variable biological tissues in vivo. Understanding of error propagation through the complex MRE reconstruction algorithms is necessary to determine the uncertainty of calculated elasticity values and the impact of different acquisition and modelling methods. We have quantified the accuracy and precision in simulated and real human brain MRE data through Monte Carlo simulations and wild bootstrap algorithm. The RMSE are low both with homoscedastic and heteroscedastic noise, which indicates high accuracy and precision of MRE reconstruction. Bootstrapping techniques are a promising method for evaluating reliability of MRE estimates of elasticity.

2601.   Ideal-Observer Based Metric for MR Image Quality Assessment - Application to Lesion Detection 
Christian G. Graff1, and Kyle J. Myers1
1Division of Imaging and Applied Mathematics, U. S. Food and Drug Administration, Silver Spring, MD, United States

We develop a metric for image quality assessment based on task performance using the Ideal (Bayesian) Observer SNR. The Ideal Observer is an upper bound for human performance and measures the ability to perform a task (in this case lesion detection) using statistical decision theory. Ideal Observer performance can be assessed from raw data or image reconstructions to measure the effectiveness of both the data acquisition and image reconstruction. This has advantages over other metrics such as SNR and CNR which are only weakly correlated with a readers ability to perform clinical tasks.

2602.   Automatic Localization of the Anterior and Posterior Commissures in MRI Brain Images Using Artificial Neural Networks 
Don C Bigler1, Megan Taylor Sutton1, and Gregory J Moore2
1Center for Emerging Neurotechnology and Imaging, Penn State Hershey Neuroscience Institute, Hershey, PA, United States, 2Radiology, Geisinger Medical Center, Danville, PA, United States

Localization of the anterior and posterior commissures is an important pre-processing step for many MR brain post-processing procedures. For large image datasets automatic localization is crucial. This work presents a method for automatic anterior and posterior commissure localization using artificial neural networks.

2603.   Ultra-high resolution atlas-based segmentation of GPi for deep brain stimulation in Parkinson’s disease 
Maria Ida Iacono1, Nikos Makris1, Luca Mainardi2, John Gale3, Andre Van der Kouwe1, Azma Mareyam1, Jonathan R Polimeni1, Lawrence L Wald1, Bruce Fischl1, Emad N Eskandar4, and Giorgio Bonmassar1
1Dept. of Radiology,MGH, A. A. Martinos Center for Biomedical Imaging, Charlestow, MA, United States, 2Bioengineering Department, Politecnico di Milano, 3Cleveland Clinic, Department of Neuroscience and Center for Neurological Restoration, Cleveland, Ohio, United States, 4Neurosurgery, Massachusetts General Hospital, Boston, MA, United States

Deep brain stimulation (DBS) of the globus pallidus internus (GPi) proves to significantly improve the motor symptoms of advanced PD. However, GPi is not clearly identifiable in pre-operative MRIs, used routinely in surgical DBS procedures. In this work we propose an atlas-based segmentation procedure based on a ultra-high resolution atlas to outline the GPi on the pre-operative low resolution images of PD patients. Our preliminary results show that a surface non-linear registration procedure based on multiple nuclei improves the accuracy in discriminating the target of interest.

Traditional Posters : Pulse Sequences, Reconstruction & Analysis
Click on to view the abstract pdf and click on to view the pdf of the poster viewable in the poster hall.
Mouse MRI

Wednesday May 11th

Exhibition Hall  13:30 - 15:30

2604.   WASSR imaging of Iron Oxide Particles at 2.35 and 7T 
Jean-Sebastien Raynaud1, Antony Lee1, Caroline Robic1, Eric Giaccomini2, Isabelle Raynal1, Philippe Robert1, Franck Lethimonier2, Marc Port1, and Claire Corot1
1Guerbet Research, Paris, France, 2Neurospin, CEA, Saclay, France

During the last decade, different approaches were designed to detect USPIO. “Positive contrast” imaging based on a single off resonance RF excitation suffers of low sensitivity and miss registrated spatial localization. A way to avoid these drawbacks is the ORS sequence, based on a long RF saturation to affect off resonance water diffusible protons. The purpose of this study was to investigate a new sequence initially performed for CEST imaging, WASSR, to combined strong contrast, high sensitivity and quantification. This sequence was evaluated on Iron and Gadolinium based contrast agents in in vitro conditions at clinical and research fields.

2605.   WASSR imaging of lower case Greek alphavlower case Greek beta3 targeted USPIO at 2.35T on U87 mice tumors : feasibility study 
Jean-Sebastien Raynaud1, Antony Lee1, Xavier Violas1, Robin Santus1, Gaelle Louin1, Isabelle Raynal1, Philippe Robert1, Marc Port1, and Claire Corot1
1Guerbet Research, Paris, France

In this study, we purpose to adapt a modified ORS sequence, WASSR (WAter Saturation Shift Referencing), initially applied on CEST contrast, to investigate in vitro and in vivo detection of a targeted USPIO in a clinical field. Preliminary result on U87 mice tumors, shows the ability of the WASSR sequence to provide an original approach for in vivo USPIO imaging combining contrast, sensitivity, quantification and appropriate spatial resolution, in clinical considerations (clinical field and low SAR).

2606.   Slice ordering for cardio-respiratory triggered imaging of the whole liver in the mouse 
Sean Smart1, Danny Allen1, John Beech1, Sally Hill1, Veerle Kersemans1, Lei Zhao1, and Ruth Muschel1
1Gray Institute, Oxford University, Oxford, Oxfordshire, United Kingdom

We describe a slice ordering scheme used in conjuntion with cardio-respiratory triggering that is used to generate T2 weighted images of liver that are free of motion artefact. The scheme allows high resolution imaging of the whole liver in the mouse within an acceptable scan time.

2607.   Feasibility of High Resolution Mouse Brain Spiral Imaging at Very High Field (11.75T) for Perfusion Studies 
Mohamed Tachrount1, Virginie Callot1, Patrick J. Cozzone1, and Guillaume Duhamel1
1CRMBM / CNRS 6612, Faculté de Médecine, Université de la Méditerranée, Marseille, France

Fast imaging sequences (e.g. EPI) are required for small animal studies which include multimodal approaches. With the increasing fields, EPI may not be applicable due to the increase of image distortions or strong susceptibility artifacts. Spiral imaging could be a good alternative as it offers similar acquisition speed performance with less sensitivity to susceptibility artifacts and motion. However, its successful application can be challenging because of B0 inhomogeneities and gradients imperfections. This works presents the investigation of spiral imaging feasibility at very high field (11.75T) for mouse brain imaging and, its application for brain perfusion study perfomed with ASL.

Traditional Posters : Pulse Sequences, Reconstruction & Analysis
Click on to view the abstract pdf and click on to view the pdf of the poster viewable in the poster hall.
Dental MRI

Thursday May 12th
Exhibition Hall  13:30 - 15:30

2608.   Paleo-NMR: micro-imaging of skeletal and odontoskeletal remains 
Silvia Capuani1,2
1Physics Department Sapienza University of Rome, Rome, Italy, 2CNR IPCF UOS Roma, Rome, Italy

Micro-MRI data compared to micro-CT, demonstrate that virtual histology of ancient bones and archeological teeth, based on micro-NMR images, can highlight some details that are not detectable with other non destructive techniques. In particular MRI shows an exquisite ability to investigate microstructural features of dentine and bone. As brain size, and other life-history traits correlate tightly with dental development while bones can tell us all about lifestyle, habits, diseases and death causes of our distant ancestors, the investigation proposed here may result a decisive support to paleo-pathological research and anthropological studies.

2609.   Assessment of Cortical Bone Resorption and Acute Inflammation in Parodontitis 
Anna-Katinka Bracher1, Michael Mess1,2, Axel Bornstedt1, Erich Hell3, Johannes Ulrici3, Bernd Haller2, and Volker Rasche1
1Department of Internal Medicine II, University Hospital of Ulm, Ulm, Germany, 2Department of Operative Dentistry, Periodontology and Pedodontics, University of Ulm, Ulm, Germany, 3Sirona Dental Systems, Bensheim, Germany

Assessment of acute inflammation and chronic bone resorption is the basic information required for the diagnosis, staging and therapy monitoring of parodontitis. The application of MRI for assessment of the acute inflammation and bone resorption in parodontitis is investigated. It could be shown that besides the assessment of the acute inflammation, a T1 weighted MRI sequence can be used for achieving a clear delineation between spongoues bone, cortical bone, and saliva, which enables the volumetric assessment of the bone resorption.

2610.   Towards dental MRI: Zero TE imaging of compromised equine teeth 
Stefan Zwick1, Jan-Bernd Hövener1, Jochen Leupold1, Frank Schellenberger2, and Dominik v. Elverfeldt1
1Department of Radiology, Medical Physics, University Hospital Freiburg, Freiburg, Germany, 2Dr. Frank Schellenberger Hypo Dental

Most endodontal diseases of equine teeth can’t be diagnosed at an early stage because of unspecific symptoms and lack of diagnostic tools. Often secondary manifestations permit diagnosis years after the onset; too late for early restorative treatment. Here, we show that ZTE imaging at 9.4T can image solid components of horse tooth and visualize inherent structural differences between healthy and impaired pulps. Clearly, high-field MRI will not become standard veterinarian equipment as well as dental MRI will not get into clinical routine. However, methods like ZTE widen the field of MRI as shown by proof-of-principle studies like the presented one.

2611.   Accurate In Vivo Assessment of Caries Lesion Extent by UTE MRI 
Anna-Katinka Bracher1, Chrisitan Hofmann1,2, Axel Bornstedt1, Erich Hell3, Johannes Ulrici3, Bernd Haller2, and Volker Rasche1
1Department of Internal Medicine II, University Hospital of Ulm, Ulm, Germany, 2Department of Operative Dentistry, Periodontology and Pedodontics, University of Ulm, Ulm, Germany, 3Sirona Dental Systems, Bensheim, Germany

Ultra-short echo time MRI has been shown to provide information on early formation of caries lesions and demineralization. In this contribution the role of MRI for the accurate assessment of the extent of caries lesions is investigated in vivo. It is shown that MRI often predicts the lesion size more accurate than the clinically established X-ray based imaging techniques.

2612.   High-Resolution ZTE Imaging of Human Teeth 
Markus Weiger1,2, Klaas Paul Pruessmann3, Anna-Katinka Bracher4, Sascha Köhler2, Volker Lehmann5, Uwe Wolfram6, and Volker Rasche4
1Bruker BioSpin AG, Faellanden, Switzerland, 2Bruker BioSpin MRI GmbH, Ettlingen, Germany, 3Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland, 4Internal Medicine II, University of Ulm, Ulm, Germany, 5Bruker BioSpin GmbH, Rheinstetten, Germany, 6Institute of Orthopaedic Research and Biomechanics, University of Ulm, Ulm, Germany

ZTE is an MRI technique with 3D radial centre-out encoding and zero echo time, particularly suited for imaging samples with short T2. In this work, the short-T2 capability, robustness, and efficiency of ZTE are used for high-resolution in-vitro imaging of human teeth. Images with excellent image quality are obtained, clearly delineating dentin and enamel. Compared with UTE, superior SNR and CNR are found for the mineralised layers. Furthermore, better sensitivity to demineralisation is observed compared with x-ray-based microscopic imaging.

2613.   Assessment of Bone Degradation and Acute Inflammation in Apical Parodontitis 
Anna-Katinka Bracher1, Axel Bornstedt1, Erich Hell2, Johannes Ulrici2, Leif-Konradin Sailer3, and Volker Rasche1
1Department of Internal Medicine II, University Hospital of Ulm, Ulm, Germany, 2Sirona Dental Systems, Bensheim, Germany, 3DOC, Praxisklinik im Wiley, Neu-Ulm, Germany

The identification of the culprit lesion in apical parodontitis is often difficult due to the only limited performance of X-ray based techniques in delineation of acute and chronic inflammation. We applied MRI in 11 pain patients and compared the outcome with cone beam CT images. T2-weighted MRI appears to be a promising tool for the identification of the acute inflamed lesion and clearly outperforms X-ray based techniques.

2614.   Quantitative UTE MRI of Human Temporomandibular Disc: Relation to Biomechanical Property 
Won C Bae1, Sheronda Statum1, Reni Biswas2, Robert L Sah2, Jiang Du1, and Christine B Chung1
1Radiology, University of California, San Diego, San Diego, CA, United States, 2Bioengineering, University of California, San Diego, La Jolla, CA, United States

Disorders of the temporomandibular joint (TMJ) may involve biomechanical weakening of the TMJ disc. TMJ tissues have inherently short T2 values and their quantitative evaluation benefits from ultrashort time-to-echo (UTE) MR techniques. This study evaluated relation between MR properties (conventional SE T2, UTE T2* and UTE T1rho) and biomechanical indentation stiffness of human TMJ discs. For certain range of indentation stiffness values, UTE T1rho correlated strongly with indentation stiffness, while SE T2 values correlated more weakly. Sensitivity of UTE T1rho values to biomechanical properties make it useful longitudinal evaluation of TMJ discs.

Traditional Posters : Pulse Sequences, Reconstruction & Analysis
Click on to view the abstract pdf and click on to view the pdf of the poster viewable in the poster hall.
Cardiac Sequences: Applications & Evaluations

Monday May 9th
Exhibition Hall  14:00 - 16:00

2615.   k-space Sampling Approaches Using TWIST: Implications for Dynamic Contrast Acquisitions 
Xin Li1, John W. Grinstead2, Cecily V. Bishop3, Ian J. Tagge1, Richard L. Stouffer3,4, William D. Rooney1, and Gerhard Laub5
1Advanced Imaging Research Center, Oregon Health & Science University, Portland, Oregon, United States, 2Siemens Healthcare, Portland, Oregon, United States, 3Division of Reproductive Sciences, ONPRC, Oregon Health & Science University, Portland, Oregon, United States, 4Department of Obstetrics and Gynecology, Oregon Health & Science University, Portland, Oregon, United States, 5Siemens Healthcare, San Francisco, CA, United States

Time-resolved angiography with stochastic trajectories (TWIST) pulse sequence offers a practical and flexible way to perform sub-second, time-sequential 3D measurements. It is often used in combination with contrast injection to provide dynamic clinical information. Using a primate model (rhesus macaque) and simulated data therein, we investigated TWIST center of k-space updating strategy on Dynamic-Contrast-Enhanced (DCE) MRI signal time-course and image.

2616.   Improved Motion-Sensitized Driven-Equilibrium (iMSDE) Prepared 3D GRASE for High Field Magnetic Resonance Imaging of Carotid Artery Wall 
Linqing Li1, Alistair C Lindsay2, Matthew D Robson1, and Peter Jezzard1
1FMRIB Centre, University of Oxford, Oxford, United Kingdom, 2Department of Cardiovascular Medicine, University of Oxford, Oxford, United Kingdom

Recently, an alternative black blood preparation technique of improved MSDE (iMSDE) has been proposed for vessel wall imaging. In this study, we combine the iMSDE black-blood (BB) module with a 3D GRASE imaging readout to create a robust clinically relevant protocol that is more time efficient in its data acquisition, less demanding in RF power deposition, and with improved BB characteristics at high field, in order to better differentiate vessel wall from lumen. T1, T2 and proton density weighted 3D GRASE images were acquired for comparison with the corresponding images from double inversion-recovery (DIR) and iMSDE 2D TSE techniques.

2617.   Carotid and Jugular Vessel Wall Imaging - A Study 
Karan Dara1,2, Daniel P Hsu2,3, Jamal J Derakhshan1,2, John A Jesberger2, Jeffrey L Duerk1,2, Vikas Gulani2, Jeffrey L Sunshine2, Teresa L Carman4, and Mark A Griswold1,2
1Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio, United States, 2Department of Radiology, University Hospitals of Cleveland, Cleveland, Ohio, United States, 3Department of Neurosurgery, University Hospitals of Cleveland, Cleveland, Ohio, United States, 4Department of Vascular Medicine, University Hospitals of Cleveland, Cleveland, Ohio, United States

Stroke and atherosclerosis are major causes of morbidity and death. A recently developed dark blood (DB) prepared TrueFISP sequence called HEFEWEIZEN directionally suppresses blood flow in carotid and jugular vessels to better visualize vessel walls and the remodeling processes. This study aims at determining the efficacy of HEFEWEIZEN against 3D-TOF and 2D DB-TSE sequences. At a 95% confidence interval, HEFEWEIZEN images had an advantageous significant difference over the following: TrueFISP and TOF images in vessel wall visibility and visible flow suppression; T1-, T2- and PD-wt DB-TSE images in perceived image quality; and T1-, T2- and PD-wt DB-TSE images in contrast.

2618.   Comparison of short diffusion preparations for 3D black blood imaging. 
Niranjan Balu1, Jinnan Wang2, and Chun Yuan1
1Radiology, University of Washington, Seattle, Washington, United States, 2Philips Research North America, Seattle, Washington, United States

Fast isotropic 3D black-blood imaging using diffusion prepared rapid gradient echo imaging can provide improved SNR with short diffusion preparations to reduce T2 related signal loss. Since good blood-suppression in this technique can be maintained by low turbo factors in conjunction with moderate gradient first moments, advantages of using a twice refocused diffusion preparation is not clear compared to other short preparations such as reverse bipolar diffusion gradients. We demonstrate the advantage of twice refocused preparation for medium and low first gradient moment applications of diffusion prepared 3D gradient echo black blood imaging.

2619.   Validation of Nonrigid Registration for Cardiac Cine MR Time Series 
Guyu Li1, Li Zhang1, Christoph Guetter1, and Christophe Chefd'hotel1
1Siemens Corporate Research, Princeton, New Jersey, United States

Validation of cardiac image registration has been a challenging task due to the lack of ground truth and severe through-plane motion. Since a consistent and transitive registration algorithm is more likely to find a biologically meaningful mapping, we focused on evaluating the consistency, transitivity, and consistency sensitivity to cardiac motion as the indicators of registration performance. A diffeomorphic nonrigid registration was compared with its symmetric version using 10 cardiac cine MR time series (SSFP, 1.5T) that were acquired from 10 volunteers. With the proposed criteria, we can give a more comprehensive picture of the registration performance on cardiac data sets.

Xue Feng1, Michael Salerno2, Christopher M Kramer2,3, and Craig H Meyer3,4
1University of Virginia, Charlottesville, VA, United States, 2Medicine, University of Virginia, Charlottesville, Virginia, United States, 3Radiology, University of Virginia, Charlottesville, Virginia, United States, 4Biomedical Engineering, University of Virginia, Charlottesville, Virginia, United States

Cartesian and radial balanced SSFP (bSSFP) sequences are widely used clinically for real time cardiac imaging. Spiral bSSFP sequences have been used in several research studies, but clinical adoption has been slow. The goal of this study is to compare the performance of radial and spiral bSSFP in real time cardiac imaging. In addition, a new spiral-in/out bSSFP is developed by putting a symmetrical spiral-in gradient in front of traditional spiral-out gradient to explore the TE = TR/2 mechanism and realize 0th and 1st gradient moment nulling via symmetry to save time. This sequence is also compared.

2621.   On the Advantages of Retrospectively Gated Radial Acquisitions for Cine Phase Contrast Flow Imaging 
Ashley Gould Anderson III1, Andrew L Wentland1,2, Kevin M Johnson1, and Oliver Wieben1,2
1Medical Physics, University of Wisconsin, Madison, Wisconsin, United States, 2Radiology, University of Wisconsin, Madison, Wisconsin, United States

Advantages of retrospective cardiac gating with radial acquisitions over prospectively gated Cartesian are presented. Two specific examples of phase contrast imaging where prospectively gated Cartesian sequences fail to capture important portions of the cardiac cycle are provided. The first example demonstrates the consequences of ECG trigger delay for measuring pulse wave velocity in the aorta. The second example highlights the ability to use a peripheral gating signal with retrospective gating where prospective gating would require an ECG.

2622.   Simultaneous Nulling of Fat and Viable Myocardium in Delayed Enhancement Imaging - A New Approach to Fat Suppression at 1.5 and 3 Tesla Employing Multiple SPAIR Pulses 
Wolfgang Gerhard Rehwald1, Elizabeth R Jenista2, Denise L Morell2, Nayla Chaptini2, Deneen M Spatz2, Enn-Ling Chen2, and Raymond J Kim2
1Cardiovascular MR R&D, Siemens Healthcare, Chicago, Ilinois, United States, 2Duke Cardiovascular MR Center, Duke University Medical School, Durham, North Carolina, United States

In delayed enhancement imaging (DE), fat is commonly suppressed by fat-selective saturation before readout. This is suboptimal due to its short T1. In turbo-spin echo, fat is well suppressed with the SPAIR pulse, making its combination with DE imaging desirable. Due to the inversion recovery pulse (NSIR) and TI of about 350ms, adding a SPAIR pulse with TIfat is insufficient, because fat has not fully recovered from the IR. The effective TIfat may be so short that fat nulling is impossible. We developed a combination of NSIR and two SPAIR pulses to null fat in DE without above limitations.