Electronic poster

Wednesday 13:30-15:30 Computer 119

13:30 4999. Accurate Susceptibility Quantification from MR Phase Data Through the Least Squares Fit Method: Phantom Validation

Jaladhar Neelavalli^1,2, Yu-Chung Norman Cheng³, Mudassar Kamran², James V. Byrne², Ewart Mark Haacke<sup>3

1</sup>The MRI Institute for Biomedical Research, Detroit, MI, United States; ²Nuffield Department of Surgery, University of Oxford, Oxford, Oxfordshire, United Kingdom; ³Academic Radiology, Wayne State University, Detroit, MI, United States

We utilize a Fourier based method of quantifying the magnetic susceptibilities of arbitrarily shaped objects with medium sizes in a phantom. The method uses the phase images and an iterative 3D least-squares fitting algorithm. The quantified susceptibility has an 11% uncertainty, which is due to the pixelization (or systematic) error.

14:00 5000. Multi Echo Susceptibility Weighted Imaging: Improving Image Contrast by Applying the Susceptibility Weighted Phase Mask to Maps of the R2* Decay

Christian Denk¹, Alexander Rauscher<sup>1

1</sup>UBC MRI Research Centre, University of British Columbia, Vancouver, BC, Canada

Maps of R2* relaxation computed from multi echo susceptibility weighted images (SWI) were multiplied with phase mask obtained from the same data. This procedure leads to an improved contrast between grey matter and white matter compared to standard SWI data processing.

14:30 5001. Susceptibility Weighted Imaging (SWI) of the Kidney at 3T – Initial Results

Moritz Mie¹, Johanna C. Nissen², Frank G. Zöllner¹, Melanie Heilmann¹, Henrik J. Michaely², Stefan O. Schönberg², Lothar R. Schad<sup>1

1</sup>Department of Computer Assisted Clinical Medicine, Heidelberg University, Mannheim, Germany; ²Institute of Clinical Radiology and Nuclear Medicine, Heidelberg University, Mannheim, Germany

SWI has been investigated for its applicability to renal imaging. To handle the problems of organ motion and a higher oxygenation level of the kidneys compared to the brain, the acquisition time has been cut down to allow for breath-hold examinations and different post-processing methods were investigated. Results showed that our new post-processing strategy could produce a susceptibility weighted contrast enhancement by a factor of 1.5 compared to the standard approach. The results represent initial experiences with the SWI for abdominal imaging which proof the principal feasibility.

15:00 5002. Field-Corrected 3D Multiecho Gradient Echo: Simultaneous Extraction of Quantitative R2*, T2* Weighting, SWI, and Venography

Robert Marc Lebel¹, Alan W. Wilman<sup>1

1</sup>Biomedical Engineering, University of Alberta, Edmonton, Alberta, Canada

Susceptibility weighted imaging incorporates phase information to enhance image contrast. We employ multiecho 3D gradient-echo, with a rapid pre-scan to minimize diverging phase ramps in the readout direction, with advanced post-processing techniques to correct for macroscopic field gradients to generate multiple high quality data sets from a single scan. Ultimately this technique yields the following low-artifact, high-resolution data sets: (1) T2*-weighted images, (2) quantitative R2* maps, (3) SWI, and (4) venography.

Thursday 13:30-15:30 Computer 119

13:30 5003. Resolving Phase: Inversion of SWI-Phase Data in Order to Obtain Its Sources Utilizing the Concept of a Generalized Lorentzian Approximation

Ferdinand Schweser¹, Moritz Hütten², Berengar Wendel Lehr², Andreas Deistung², Daniel Güllmar², Jürgen Rainer Reichenbach<sup>2

1</sup>Medical Physics Group, Department of Diagnostic and Interventional Radiology , Jena University Hospital, Jena, Germany; ²Medical Physics Group, Department of Diagnostic and Interventional Radiology, Jena University Hospital, Jena, Germany

Phase data acquired at multiple orientations with respect to the magnetic field was inverted to susceptibility, rotation-invariant local shift, and anisotropy-related susceptibility. Results indicate that gray-to-white matter contrast in phase images is dominated by sources from magnetic susceptibilities rather than macro-molecular exchange processes.

14:00 5004. Reconstruction of Multi-Echo High-Resolution T2* and Phase Imaging Data Acquired at 3 Tesla Using a 32 Channel Head Coil

Claudiu Schirda¹, Anthony Vu², Robert Zivadinov<sup>1

1</sup>Buffalo Neuroimaging Analysis Center, University at Buffalo, Buffalo, NY, United States; ²GE Healthcare, Milwaukee,, WI, United States

Susceptibility weighted imaging (SWI) has been shown to be a useful technique for visualization of small veins, of iron deposits and micro bleeds in vivo brain, among other applications. Because the susceptibility effects present in the image are dependent on the echo time, a multi-echo acquisition like SWAN, even when using just the magnitude information, will be able to provide complimentary information. Using the free (no extra acquisition time) information that is found in the phase image, thus SWAN with phase reconstruction, enables one to obtain a wealth of information. A number of challenges are presented when using a 32 channel coil for data acquisition and we present solutions to these challenges.

14:30 5005. Order of Magnitude Speedup for Iterative Algorithms in Quantitative Susceptibility Mapping Using Multi-Core Parallel Programming

Deqi Cui^1,2, Tian Liu¹, Pascal Spincemaille³, Yi Wang

¹Biomedical Engineering, Cornell University, New York, NY, United States; ²Optic electronics, Beijing Institute of Technology, Beijing, China; ³Radiology, Weill Cornell Medical College, New York, NY, United States

Iterative susceptibility reconstructions requires four Fast Fourier Transforms in every iteration and hundreds of iterations to converge. Although the iteration is hard to disperse, FFT can be computed in parallel. In this study, a parallelized FFT based on OpenMP was implemented to achieve quasi real-time susceptibility map reconstructions.

15:00 5006. A T₂^* Selective Higher-Order Soliton Preparation Pulse for MRI

Marcin Jankiewicz^1,2, Jay Moore^1,3, Adam W. Anderson^1,4, John C. Gore<sup>1,4

1</sup>Institute of Imaging Science, Vanderbilt University, Nashville, TN, United States; ²Department of Radiology, Vanderbilt University, Nashville, TN, United States; ³Department of Physics, Vanderbilt University; ⁴Department of Biomedical Engineering, Vanderbilt University

The soliton pulses represent a promising solution to the problem of designing T₂^* selective preparation pulses. The pulses are characterized by a set of complex parameters. Their interpretation is only partially understood in the context of MRI. For example, some of them correspond to values of relaxation times for which the magnetization vector will be nulled. A preliminary analysis of the behavior of such pulses is presented here with the goal of demonstrating the versatility of such pulses in producing a range of T₂^* contrasts.

Gating & Triggering

Hall B Monday 14:00-16:00 Computer 120

14:00 5007. Rapid Frame-Rate MR Acquisitions to Reveal Mechanisms of Circular Breathing and Sound Production in the Australian Aboriginal Didgeridoo

Graham Charles Wiggins¹, Pippa Storey<sup>1

1</sup>Radiology, NYU Medical Center, New York, NY, United States

The Australian Aboriginal wind instrument known as the didgeridoo is played using techniques that are unusual in Western music. A continuous sound is maintained through circular breathing, in which the mouth is used as a pump to keep air flowing into the instrument while inhaling through the nose. Traditional playing technique involves interdental articulation that differs from Western tonguing. We used rapid FLASH acquisitions to capture the circular breathing cycle and reveal the mechanics involved. This may serve as an aid to teaching proper playing technique.

14:30 5008. Cardiac Imaging at 7.0T: Comparison of Pulse Oximetry, Electrocardiogram and Phonocardiogram Triggered 2D CINE for Left Ventricular Function Assessment

Tobias Frauenrath¹, Fabian Hezel¹, Wolfgang Renz², Florian von Knobelsdorff-Brenkenhoff³, Thibaut de Geyer d’Orth¹, Marcel Prothmann³, Matthias Dieringer¹, Kerstin Kretschel³, Jeanette Schulz-Menger^3,4, Thoralf Niendorf<sup>1,4

1</sup>Berlin Ultrahigh Field Facility, Max-Delbrueck Center for Molecular Medicine, Berlin, Germany; ²Siemens Medical Solutions, Erlangen, Germany; ³Franz-Volhard-Klinik for Cardiology, Helios Klinikum Berlin-Buch, Charité Campus Buch, Germany; ⁴Experimental and Clinical Research Center (ECRC), Charité Campus Buch, Humboldt-University, Berlin, Germany

As ultrahigh field cardiac MRI becomes more widespread in the (pre)clinical research arena the propensity of ECG recordings to interference from electromagnetic fields and magneto-hydrodynamic effects increases and with it the motivation for a practical gating/triggering alternative. This study compares the feasibility, efficacy and reliability phonocardiogram (ACT), vector electrocardiogram (VCG) and traditional pulse oximetry (pO2) triggered MRI for left ventricular function assessment at 7.0T. ACT’s intrinsic insensitivity to interference from electro-magnetic fields and magneto-hydrodynamic effects results in an excellent trigger reliability and renders it suitable for global cardiac function assessment at ultrahigh magnetic field strengths.

15:00 5009. Magnetic Field Gradient Artifact Reduction on ECG for Improved Triggering

Julien Oster^1,2, Olivier Pietquin^1,3, Michel Kraemer⁴, Jacques Felblinger<sup>1,2

1</sup>U947, Inserm, Vandoeuvre-les-Nancy, France; ²IADI, Nancy-Université, Nancy, France; ³IMS Research Group, Supelec Metz Campus, Metz, France; ⁴Schiller Médical, Wissembourg, France

Cardiac MR Acquisitions have to be synchronized with heart activity to prevent from motion artifacts. Electrocardiogram (ECG) is therefore the most accurate tool. Magnetic Field Gradients (MFG) artifacts are unfortunately induced on ECG signals. In this paper a new real-time MFG artifact reduction method is presented. This technique is based on the merging of both ECG and MFG artifact models. An estimation of the model parameters is recursively updated by nonlinear Bayesian filtering. The MFG signals can then be filtered with the MFG artifact model parameters in real-time. The herein presented method outperforms state-of-the-art algorithms and enables accurate triggering.

15:30 5010. High Resolution, Free-Breathing Coronary Artery Imaging with >99% Respiratory Efficiency: Comparing Beat to Beat Respiratory Motion Correction with Navigator Gating

Andrew David Scott^1,2, Jennifer Keegan, ^1,2, David N. Firmin, <sup>1,2

1</sup>National Heart and Lung Institute, Imperial College, London, Greater London, United Kingdom; ²Cardiovascular Magnetic Resonance Unit, The Royal Brompton Hospital, London, Greater London, United Kingdom

Respiratory motion correction using highly efficient localized beat-to-beat epicardial fat tracking was compared to standard navigator gating using high resolution right coronary artery imaging. Beat-to-beat corrections were applied to 3D spiral acquisitions (99.3% respiratory efficiency) and navigator gating applied to 3D magnetization-prepared balanced steady-state-free-precession acquisitions (44% efficient) in ten healthy subjects. Quantitative comparison was performed using vessel diameter and vessel sharpness. Results were not substantially different between techniques and the study highlights the importance of the localized nature of the beat-to-beat respiratory-motion-correction.

Tuesday 13:30-15:30 Computer 120

13:30 5011. Efficient Navigator-Gated Acquisition of Different Breathing Positions During Free Breathing Applied to Flow Measurements in the Great Vessels

Sebastian Gruhlke¹, Michael Markl¹, Bernd André Jung<sup>1

1</sup>University Hospital Freiburg, Freiburg, Germany

To investigate physiological effects of the breathing position on blood flow, a double navigator-gated sequence was implemented defining two acceptance windows during expiration and inspiration. The method permitted to acquire flow sensitive phase contrast MRI data during both in- and expiration within a single scan with optimal scan efficiency. The sequence was applied to measure the dependency of time resolved blood flow on in- and expiration during breath-hold and free breathing as well as valsalva maneuver in the major vessels. In-vivo measurements could detect respiration related difference in blood flow even during free breathing

14:00 5012. Retrospective Bellows-Based Reconstruction for Cardiac MRI: Preliminary Experience

Claudio Santelli¹, Reza Nezafat¹, Warren J. Manning^1,2, Sebastian Kozerke³, Dana C. Peters<sup>1

1</sup>Cardiology, Beth Israel Deaconess Medical Center, Boston, MA , United States; ²Radiology, Beth Israel Deaconess Medical Center, Boston, MA, United States; ³D-ITET, ETH Zurich, Institute for Biomedical Engineering, Zurich, Switzerland

We evaluated the relationship between the respiratory bellows, placed on the chest, and the abdomen, and the superior-inferior displacement of the navigator signal, the lung-liver interface, and the heart, in single-heart-beat ECG-gated images. The diaphragmatic bellows correlated better than the chest wall bellows, and bellows correlated best with the navigator. Using a bellows based criteria, 3D coronary MRI was reconstructed retrospectively, based on the bellows data only. Our preliminary experience suggests that bellows-gating should be revisited.

14:30 5013. Prospective Diaphragm Position Prediction for Cardiac MR Using Multiple Navigators

Ian Hamilton Burger¹, Jennifer Keegan^2,3, Ernesta Meintjes¹, David Firmin<sup>2,3

1</sup>Human Biology, University of Cape Town, Cape Town, Western Cape, South Africa; ²CMR Unit, Royal Brompton Hospital Trust, London, United Kingdom; ³Imperial College London

Prediction of the diaphragm position during imaging segments by multiple navigators and a predictor estimator during the preceding systole. The control system compares the navigator records to a model and feeds back the difference between the model and recorded value to prevent the model from diverging. This data can then be used to improve prospective slice following and increase acceptance window and increase respiratory efficiency.

15:00 5014. Motion Compensated Reconstruction for Thoracoabdominal Dynamic Contrast-Enhanced MRI in
Free-Breathing

Marina Filipovic^1,2, Pierre-André Vuissoz^1,2, Andrei Codreanu³, Michel Claudon⁴, Jacques Felblinger<sup>1,5

1</sup>INSERM-U947, Nancy, France; ²Laboratory IADI, Nancy-Université, Nancy, France; ³Centre Hospitalier de Luxembourg; ⁴University Hospital Nancy; ⁵INSERM-CIC801

Physiological motion often impairs the analysis of abdominal and thoracic dynamic contrast-enhanced MRI, by causing motion-induced artefacts and misregistration. A previously published reconstruction algorithm, GRICS, corrects for motion-induced artifacts in a single image reconstruction. A novel method has been developed by modifying GRICS with the purpose of performing whole motion compensation in dynamic contrast-enhanced MRI. The performance is demonstrated on 6 myocardial perfusion MRI data sets and on one simulated data set. The results present elastic registration and motion-artefact correction of the image series, in order to allow for more accurate time-intensity curves analysis and for a simplified post-processing.

Wednesday 13:30-15:30 Computer 120

13:30 5015. 3D Free-Breathing Cardiac Cine Imaging with Respiratory and Cardiac Self-Gating and 3D Motion Correction

Jing Liu¹, Thanh D. Nguyen¹, Pascal Spincemaille¹, Noel CF Codella¹, Martin R. Prince¹, Yi Wang<sup>1

1</sup>Radiology, Weill Cornell Medical College, New York, NY, United States

A 3D radial cardiac cine imaging technique provides reliable 3D motion tracking from the data acquisition for image reconstruction. 3D tracked motions are used for robust respiratory and cardiac self-gating and also allows 3D motion correction.

14:00 5016. High Spatial and Temporal Resolution Free Breathing Cardiac CINE-GRICS : 512x512 Vs 128x128 Matrix

Pierre-André Vuissoz^1,2, Freddy Odille³, Brice Fernandez, ^1,4, Maelene Lohezic, ^1,4, Adnane Benhadid^1,2, Damien Mandry^2,5, Jacques Felblinger<sup>1,6

1</sup>Imagerie Adaptative Diagnostique et Interventionnelle, Nancy-Université, Nancy, France; ²U947, INSERM, Nancy, France; ³Centre for Medical Image Computing, University College London, London, United Kingdom; ⁴Global Applied Science Lab., GE healthcare, Nancy, France; ⁵Departments of Radiology, University Hospital Nancy, Nancy, France; ⁶CIC801, INSERM, Nancy, France

In cardiac MRI, myocardium function is usually studied through breath hold acquisitions, limiting the achievable spatial and temporal resolution. The recently proposed CINE-GRICS algorithm allows reconstructing cardiac cine images from free-breathing scans without any limitation regarding spatial resolution, as motion is corrected for by a motion model. In 2D short axis balanced-SSFP scans, we assess the benefit of using the motion-compensated strategy for high spatial and temporal resolution CINE, with matrix sizes from 128x128 to 512x512. Resulting images were assessed visually and using entropy-based metrics, and showed improved sharpness and better depiction of fine cardiac structures.

14:30 5017. Reducing the Sensitivity to Respiratory Motion of Modified Look-Locker with Saturation Recovery for Cardiac T1 Mapping

Ting Song^1,2, Vincent B. Ho^2,3, Glenn Slavin¹, Maureen N. Hood^2,3, Jeffrey A. Stainsby<sup>4

1</sup>GE Healthcare Applied Science Laboratory, Bethesda, MD, United States; ²Radiology, Uniformed Services University of the Health Sciences, Bethesda, MD, United States; ³Radiology, National Navy Medical Center, Bethesda, MD, United States; ⁴GE Healthcare Applied Science Laboratory, Toronto, ON, Canada

To address cardiac motion, data acquisition is limited to quiescent periods of the cardiac cycle necessitating a segmented method. However, respiratory motion resulting from failed breath holding remains an issue. If a subject fails to maintain a consistent breath hold throughout the entire scan the acquired K-space data is not consistent across segments and this can result in motion artifacts. A new scheme of segment arrangement is proposed in this context. Phantom and human studies were evaluated with the two schemes.

15:00 5018. Simulation of Motion-Induced Dark-Rim Artifacts for Cartesian and Spiral Pulse Sequences

Michael Salerno¹, Christopher M. Kramer², Craig H. Meyer<sup>3

1</sup>Department of Medicine, Cardiology, University of Virginia, Charlottesville, VA, United States; ²Department of Radiology, University of Virginia, Charlottesville, VA; ³Biomedical Engineering, University of Virginia, Charlottesville, VA

Simulation of interleaved spiral data acquisition demonstrates reduced sensitivity to motion-induced dark-rim artifacts as compared to conventional Cartesian data acquisition. Thus, spiral data acquisition strategies may be advantageous for first-pass myocardial perfusion imaging.

Thursday 13:30-15:30 Computer 120

13:30 5019. Combination of Motion Adapted Gating with Non-Rigid Motion Correction for Free-Breathing MRI

Yuji Iwadate¹, Yoshihiro Tomoda², Yoshikazu Ikezaki², Tetsuji Tsukamoto<sup>1

1</sup>MR Applied Science Laboratory, GE Healthcare Japan, Hino, Tokyo, Japan; ²MR Engineering, GE Healthcare Japan, Hino, Tokyo, Japan

The motion adapted gating (MAG) approach accelerates respiratory gating but still requires considerably longer scan time compared to a single breath-hold scan. In this work, we combined the non-rigid motion correction technique with the MAG approach to reduce scan time to the level comparable to breath-hold. A volunteer study showed that the scan time was less than 1.1-fold longer than non-gating scan and motion artifacts remaining with the MAG were reduced by non-rigid motion correction. This technique can be applied to various abdominal applications such as free-breathing dynamic contrast enhanced imaging.

14:00 5020. Using Respiratory Biofeedback Games in Pediatric MRI Examinations to Increase Patient Comfort and Facilitate Scanning – a Pilot Study

Lena Douglas¹, Rose-Marie Claesson², Bo Ehnmark², Thröstur Finnbogason², Anna-Märta Lång², Bo Nordell¹, Morten Bruvold³, Jouke Smink³, Permjit Jhooti<sup>4

1</sup>Department of Medical Physics, Karolinska University Hospital, Stockholm, Sweden; ²Department of Pediatric Radiology, Astrid Lindgren Children's Hospital, Karolinska University Hospital, Stockholm, Sweden; ³Philips Healthcare, Best, Netherlands; ⁴Radiological Physics, University Hospital of Basel, Basel, Switzerland

MRI examinations of pediatric patients can be challenging partly because many children have difficulties in lying still. The aim of this work is to introduce in respiratory controlled sequences a biofeedback game in which the child can control the flight of an airplane on a screen through the diaphragm position, as registered by standard navigator echoes. Given a task to focus on children are less likely to move during scanning leading to less motion artifacts. When playing the game the breathing pattern also becomes smoother with a more regular end-expiratory position, leading to more efficient and shorter examinations.

14:30 5021. Self-Gating Reconstruction of Multiple Respiratory Phases Using Undersampled Golden-Radial Phase Encoding Trajectory

Christian Buerger¹, Tobias Schaeffter¹, Claudia Prieto<sup>1

1</sup>Division of Imaging Sciences, King's College London, London, United Kingdom

A new self-gating acquisition scheme allowing the retrospective reconstruction of several respiratory phases is proposed. This approach takes advantage of the recently introduced Golden-Radial Phase Encoding (G-RPE) trajectory and uses the, inherently acquired, central k-space profiles to derive the respiratory motion signal. The method was tested in in-vivo data using a 32-channel coil and 3 different respiratory phases were reconstructed from undersampled data using non-Cartesian SENSE reconstruction.

15:00 5022. Phase Navigator for Respiratory Triggering

Alto Stemmer¹, Berthold Kiefer<sup>1

1</sup>Healthcare Sector, Siemens AG, Erlangen, Germany

In this work the signal for respiratory triggering is derived with a navigator that measures respiratory induced off-resonance effects. The advantages compared to a liver dome navigator are the compatibility with short bore scanners and that no navigator positioning is necessary.