13:30 | | IntroductionRalph Sinkus LVTS, U1148, INSERM, Paris, France / King's College London, UK, France |
13:42 | 0555.
| Acceleration of Magnetic Resonance Elastography using a Novel Distributed Encoding Technique Mary K Kramer1, Alex M Cerjanic2, Matthew DJ McGarry3, and Curtis L Johnson1 1Biomedical Engineering, University of Delaware, Newark, DE, United States, 2Massachussetts General Hospital, Cambridge, MA, United States, 3Dartmouth College, Hanover, NH, United States Keywords: Elastography, Elastography Motivation: Magnetic resonance elastography (MRE) data quality is susceptible to poor data quality from subject motion and long scan times. Goal(s): A novel sampling technique and estimation scheme was developed and implemented to improve flexibility and acquisition time of MRE. Approach: The technique utilizes non-traditional sampling directions in an optimized encoding matrix to collect data efficiently to be used in a novel algorithm for estimating harmonic displacement fields. This allows for acquisition acceleration or flexibility in the data sampled to be rejected in post-processing if it is distorted. Results: Scans were acquired 2.3x faster than standard methods with 95.2% multiscale structural image similarity. Impact: A novel sampling and estimation scheme demonstrated here can be used to improve the application of magnetic resonance elastography. This is accomplished through prospective reduction in sampling, reducing acquisition time, and retrospective volume rejection, circumventing distortion introduced by subject motion. |
13:54 | 0556.
| Gradient impulse response function-based phase compensation for wavelet MR elastography on a compact 3T scanner Daehun Kang1, Yi Sui1, Yuan Le1, Ziying Yin1, Myung-Ho In1, John Huston III1, Yunhong Shu1, and Matt A Bernstein1 1Radiology, Mayo Clinic, Rochester, MN, United States Keywords: Artifacts, System Imperfections: Measurement & Correction, gradient impulse response function Motivation: High-performance asymmetric gradient systems have the potential to produce high-spatial-order eddy-current-induced magnetic fields that can impact phase-based applications such as wavelet MRE using large-magnitude motion-encoding bipolar gradient pulses. Goal(s): Removal of the gradient-system-induced high-order phase deviation in the wavelet MRE phase map. Approach: Gradient impulse response functions (GIRFs) can be used to characterize the gradient system. We introduce a GIRF-based phase compensation approach to alleviate the high-order phase deviations resulting from imperfections in the gradient system, along with practical recommendations, including the use of a tailored set of GIRFs. Results: The phase inhomogeneity in wavelet-MRE phase map improved with the GIRF-based compensation. Impact: The proposed GIRF-based phase
compensation approach offers the potential to enhance phase image quality and
accuracy, addressing imperfections in the gradient system, which is a challenge
not fully resolved by alternative methods like concomitant field correction and
pre-emphasis gradient modification. |
14:06 | 0557.
| Time-resolved multifrequency cardiac MR elastography of the in-vivo human heart using a segmented gradient echo spiral sequence. Matthias Anders1, Carsten Warmuth1, Tom Meyer1, Heiko Tzschätzsch2, Josef Pfeuffer3, Jeanette Schulz-Menger4,5,6,7, Jürgen Braun2, and Ingolf Sack1 1Department of Radiology, Charité – Universitätsmedizin Berlin, Berlin, Germany, 2Institute of Medical Informatics, Charité – Universitätsmedizin Berlin, Berlin, Germany, 3Application Development, Siemens Healthcare GmbH, Erlangen, Germany, 4Charité – Universitätsmedizin Berlin, Berlin, Germany, 5Working Group On CMR, Experimental and Clinical Research Center, Berlin, Germany, 6Department of Cardiology and Nephrology, HELIOS Hospital Berlin-Buch, Berlin, Germany, 7DZHK (German Centre for Cardiovascular Research), Berlin, Germany Keywords: Elastography, Elastography Motivation: Abnormal changes in myocardial stiffness during the cardiac cycle are a potential biomarker for cardiac diseases. However, there is currently no established MR-method for time-resolved mapping of cardiac stiffness. Goal(s): To demonstrate the reproducibility of time-resolved stiffness mapping of the in-vivo human heart over the cardiac cycle by MR elastography (MRE). Approach: Eleven healthy volunteers were examined twice using multifrequency cardiac-triggered, segmented gradient echo spiral MRE for stiffness mapping of the left ventricular myocardium in a short-axis view. Results: Excellent, good, and moderate reproducibility was achieved for isovolumetric contraction, systolic, and diastolic phases, respectively. Significant differences among all phases were apparent. Impact: The achieved high reproducibility of cardiac
multifrequency MRE, together with its ability to identify distinct
time-resolved stiffness levels during the cardiac phases of isovolumetric
contraction, systole and diastole, could potentially detect stiffness related
cardiac pathology in early disease stages. |
14:18 | 0558.
| Data-Driven Analysis of Brain Tissue Mechanics using Magnetic Resonance Elastography and Non-Negative Matrix Factorization Alexa M Diano1, Olivia M Bailey1, Mary K Kramer1, Kyra E Twohy2, and Curtis L Johnson1,2 1Department of Biomedical Engineering, University of Delaware, Newark, DE, United States, 2Department of Mechanical Engineering, University of Delaware, Newark, DE, United States Keywords: Elastography, Brain Motivation: There exists a need for a comprehensive method to analyze regional brain tissue mechanics that accounts for variability across subject populations. Goal(s): Here we aimed to implement a multivariate data-driven technique to capture brain mechanical properties across a wide population while preserving small-scale differences between subjects. Approach: Non-negative matrix factorization was used to reduce mechanical properties derived from magnetic resonance elastography (MRE) into a low-dimensional form to generate unconfined regions of the brain that demonstrate high covariance across all subjects. Results: This technique was able to capture recognizable anatomical regions in the brain without structural input to determine weightings on the population average. Impact: This low-dimensional representation of brain tissue mechanics acquired from non-negative matrix factorization and MRE will help define baseline properties that accurately represent a wide range of subject populations while minimizing variability across imaging studies and contributing to improved statistical models. |
14:30 | 0559.
| Biomechanical tumor hallmarks for the clinical diagnosis of glioma by high-resolution multifrequency MR elastography Mehrgan Shahryari1, Tom Meyer1, Pablo Gottheil2, Elisabeth Hain3, Josef A. Käs2, Eberhard Siebert4, Vincent Prinz5, and Ingolf Sack1 1Department of Radiology, Charité - Universitätsmedizin Berlin, Berlin, Germany, 2Faculty of Physics and Earth Sciences, Peter Debye Institute, Leipzig University, Leipzig, Germany, 3Department of Neuropathology, Charité - Universitätsmedizin Berlin, Berlin, Germany, 4Institute of Neuroradiology, Charité - Universitätsmedizin Berlin, Berlin, Germany, 5Department of Neurosurgery, University Hospital Frankfurt, Frankfurt am Main, Germany Keywords: Elastography, Elastography Motivation: Previous studies using MR Elastography (MRE) have suggested that gliomas
exhibit reduced stiffness and viscosity. However, the interplay between
micromechanical tumor changes that determine the macroscopic mechanical
properties measured by MRE remains unclear. Goal(s): This study aims to investigate the relationship between viscoelastic
parameters measured MRE in-vivo and histopathologically quantified parameters in glioma. Approach: High-resolution multifrequency MRE with quantified histopathology was prospectively performed in 23 patients with glioma. Results: Stiffness and viscosity in gliomas are associated
with increased cell elongation, micro-vessel density, and apoptotic rate
suggesting unjamming, neovascularization and cell proliferation as biomechanically
sensitive tumor hallmarks for clinical diagnosis. Impact: In this study, we demonstrated that viscoelastic parameters, quantified by MR Elastography,
provide insights into cell mobility, cellularity, mitotic and apoptotic rates, as
well as vascularization of gliomas in-vivo.
This technique holds promise for future clinical diagnosis of neurotumors.
|
14:42 | 0560.
| Simultaneous acquisition of MR elastography, Dixon and X-ray CT like image Tomokazu Numano1, Daiki Ito1,2, Koichi Takamoto3, Hiroyo Kamio4, Nobuaki Tanabe1, Shota Konuma1, Yoshito Ishihara1, Jo Kikuchi1, Hiromu Oka1, and Hisao Nishijo3 1Radiological Sciences, Tokyo Metropolitan University, Tokyo, Japan, 2Keio University Hospital, Tokyo, Japan, 3Sports and Health Sciences, University of East Asia, Yamaguchi, Japan, 4Physical Therapy, Tokyo Metropolitan University, Tokyo, Japan Keywords: Other Musculoskeletal, Elastography Motivation: The purpose of study was integration of Dixon and X-ray CT like image technique in the GRE-MultiEcho-MRE sequence. Goal(s): The additional visualization of bone damage and water / fat compornents on MR elastography would yield benefits in evaluating radiologic skeletal muscle evaluation, since soft tissue injuries can be assessed directly related to the osseous injuries using one image modality. Approach: The effectiveness of this method was evaluated by volunteer studies using the original MRE pulse sequence and vibration system. Results: This method allows simultaneous acquisition of elastograms, wave images, water/fat component images and X-ray CT like images. Impact: For the patient, a reduction in total imaging time is beneficial. For the clinicians, images such as elastograms, wave images, water/fat component images, and X-ray CT are available simultaneously for multimodal diagnosis. |
14:54 | 0561.
| Viscoelastic properties of pancreatic ductal adenocarcinoma: ex vivo biomechanical validation of in vivo MR elastography Anne-Sophie van Schelt1,2, Nienke P.M. Wassenaar1,2, Eric Schrauben1, Jules L Nelissen1, Jurgen H Runge1,3, Marc C.V. van Turnhout4, Rob C.H. Driessen4, Jaap Stoker1,5, and Aart J Nederveen1 1Radiology and Nuclear Medicine, Amsterdam UMC, location AMC, Amsterdam, Netherlands, 2Imaging and Biomarkers, Cancer Center Amsterdam, Amsterdam, Netherlands, 3Radiology, Netherlands Cancer Institute, Amsterdam, Netherlands, 4Soft Tissue Engineering and Mechanobiology, Eindhoven University of Technology, Eindhoven, Netherlands, 5Endocrinology, Amsterdam Gastroenterology, Amsterdam, Netherlands Keywords: Elastography, Pancreas, Elastography Motivation: There are discrepancies in pancreatic MRE outcomes. Biomechanical validation of MRE in pancreatic ductal adenocarcinoma (PDAC) poses substantial challenges. Goal(s): This study aims to conduct biomechanical analysis on the surgically removed specimen and correlate this to preoperative MRE outcomes. Approach: Six PDAC patients underwent MRE prior to surgical intervention, resulting in shear wave speed (SWS) and phase angle (ф) for whole-tumor and tumor-center. Compression testing was performed on specimen at 5%-strain resulting in Young’s moduli (E). Correlation analysis was done with MRE outcomes and E. Results: Pearson’s correlation revealed a significant correlation between SWStumor-whole and E (r(6)=.857, p=.029) and фtumor-center (r(6)=.844, p=.035). Impact: Validation using ex vivo compression mechanical testing of pancreatic MRE
outcomes gives more insight in the accuracy of the measured elastic properties
in complex and inhomogeneous tumorous tissue, which is imperative for
clinical application of MRE as a predictive biomarker. |
15:06 | 0562.
| Nonlinear storage modulus quantification with MR-elastography: from in vitro to in vivo assessment Gwenaël Pagé1, Jean-Luc Gennisson1, Philippe Garteiser2, and Bernard E. Van Beers2 1Biomaps, CEA, CNRS, Orsay, France, 2Laboratory of Biomarker Imaging, INSERM, Paris, France Keywords: Elastography, Elastography Motivation: Estimating the nonlinear coefficient in MR elastography could provide a relevant mechanical parameter for tumor characterization. Goal(s): The goal of this study was to develop a method for assessing the nonlinear coefficient in MR elastography. Approach: We developed a specific MR elastography setup and a post-processing pipeline to quantify nonlinear coefficients in phantoms and mice with a tumor implanted subcutaneously. Results: In phantoms, we observed that nonlinear coefficient was able to provide a higher contrast than storage modulus to distinguish different structure. In addition, in mice, nonlinear coefficient was correlated to the entropy which is a marker of collagen distribution irregularity. Impact: The
estimation of the nonlinear coefficient provides a new biomarker to assess tissue
mechanical parameters. The relation between this parameter and tissue structure
could be relevant in tumor investigation, as tissue microarchitecture is an
important marker of tumor severity. |
15:18 | 0563.
| 3D MRE-based novel score predicts hepatocellular carcinoma development in patients with chronic hepatitis B Haimei Chen1, Jie Zhu1, Mengsi Li1, Jun Chen2, Meng Yin2, Sudhakar K. Venkatesh2, Richard L. Ehman2, and Jin Wang1 1Radiology, Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, China, 2Mayo Clinic College of Medicine, Rochester, MN, United States Keywords: fMRI Analysis, Elastography Motivation: Identifying patients with chronic hepatitis B (CHB) who are at high risk of HCC development for close monitoring to improve prognosis is crucial. Goal(s): We aimed to develop a 3D MRE-based risk score to predict HCC development in CHB patients. Approach: The novel HCC risk score was developed using liver shear stiffness and LSS, age, platelet count, and albumin. Results: Our results showed that the risk score has excellent performance for the identification of patients of HCC development, the cutoff value 55 of our risk score provided the high negative predictive value for HCC development at 3 and 5 years. Impact: MRE- based HCC risk score may be a non-invasively accurate tool for predicting HCC, which may provide a useful reference for decision-making in HCC surveillance strategy for CHB patients. |